C Examples For Beginners

C Program to Display “Hello, World!”


<span class="hljs-meta">#<span class="hljs-meta-keyword">include</span> <span class="hljs-meta-string">&lt;stdio.h&gt;</span></span>
<span class="hljs-function"><span class="hljs-keyword">int</span> <span class="hljs-title">main</span><span class="hljs-params">()</span> </span>{
   <span class="hljs-comment">// printf() displays the string inside quotation</span>
   <span class="hljs-built_in">printf</span>(<span class="hljs-string">"Hello, World!"</span>);
   <span class="hljs-keyword">return</span> <span class="hljs-number">0</span>;
}

#include <stdio.h>

int main() {

// printf() displays the string inside quotation

printf("Hello, World!");

return 0;

}

Output


<samp>Hello, World!</samp>

<samp>Hello, World!</samp>

C Program to Print an Integer


<span class="hljs-meta">#<span class="hljs-meta-keyword">include</span> <span class="hljs-meta-string">&lt;stdio.h&gt;</span></span>
<span class="hljs-function"><span class="hljs-keyword">int</span> <span class="hljs-title">main</span><span class="hljs-params">()</span> </span>{   
    <span class="hljs-keyword">int</span> number;
   
    <span class="hljs-built_in">printf</span>(<span class="hljs-string">"Enter an integer: "</span>);  
    
    <span class="hljs-comment">// reads and stores input</span>
    <span class="hljs-built_in">scanf</span>(<span class="hljs-string">"%d"</span>, &amp;number);

    <span class="hljs-comment">// displays output</span>
    <span class="hljs-built_in">printf</span>(<span class="hljs-string">"You entered: %d"</span>, number);
    
    <span class="hljs-keyword">return</span> <span class="hljs-number">0</span>;
}

#include <stdio.h>

int main() {

int number;

printf("Enter an integer: ");

// reads and stores input

scanf("%d", &number);

// displays output

printf("You entered: %d", number);

return 0;

}

Output


<samp>Enter an integer: 25
You entered: 25</samp>

<samp>Enter an integer: 25

You entered: 25</samp>

C Program to Add Two Integers


<span class="hljs-meta">#<span class="hljs-meta-keyword">include</span> <span class="hljs-meta-string">&lt;stdio.h&gt;</span></span>
<span class="hljs-function"><span class="hljs-keyword">int</span> <span class="hljs-title">main</span><span class="hljs-params">()</span> </span>{    

    <span class="hljs-keyword">int</span> number1, number2, sum;
    
    <span class="hljs-built_in">printf</span>(<span class="hljs-string">"Enter two integers: "</span>);
    <span class="hljs-built_in">scanf</span>(<span class="hljs-string">"%d %d"</span>, &amp;number1, &amp;number2);

    <span class="hljs-comment">// calculating sum</span>
    sum = number1 + number2;      
    
    <span class="hljs-built_in">printf</span>(<span class="hljs-string">"%d + %d = %d"</span>, number1, number2, sum);
    <span class="hljs-keyword">return</span> <span class="hljs-number">0</span>;
}

#include <stdio.h>

int main() {

int number1, number2, sum;

printf("Enter two integers: ");

scanf("%d %d", &number1, &number2);

// calculating sum

sum = number1 + number2;

printf("%d + %d = %d", number1, number2, sum);

return 0;

}

Output


<samp>Enter two integers: 12
11
12 + 11 = 23</samp>

<samp>Enter two integers: 12

12 + 11 = 23</samp>

C Program to Multiply Two Numbers


<span class="hljs-meta">#<span class="hljs-meta-keyword">include</span> <span class="hljs-meta-string">&lt;stdio.h&gt;</span></span>
<span class="hljs-function"><span class="hljs-keyword">int</span> <span class="hljs-title">main</span><span class="hljs-params">()</span> </span>{
    <span class="hljs-keyword">double</span> a, b, product;
    <span class="hljs-built_in">printf</span>(<span class="hljs-string">"Enter two numbers: "</span>);
    <span class="hljs-built_in">scanf</span>(<span class="hljs-string">"%lf %lf"</span>, &amp;a, &amp;b);  
 
    <span class="hljs-comment">// Calculating product</span>
    product = a * b;

    <span class="hljs-comment">// Result up to 2 decimal point is displayed using %.2lf</span>
    <span class="hljs-built_in">printf</span>(<span class="hljs-string">"Product = %.2lf"</span>, product);
    
    <span class="hljs-keyword">return</span> <span class="hljs-number">0</span>;
}

#include <stdio.h>

int main() {

double a, b, product;

printf("Enter two numbers: ");

scanf("%lf %lf", &a, &b);

// Calculating product

product = a * b;

// Result up to 2 decimal point is displayed using %.2lf

printf("Product = %.2lf", product);

return 0;

}

Output


Enter two numbers: <span class="hljs-number">2.4</span>
<span class="hljs-number">1.12</span>
Product = <span class="hljs-number">2.69</span>

Enter two numbers: 2.4

1.12

Product = 2.69

C Program to Print ASCII Value


<span class="hljs-meta">#<span class="hljs-meta-keyword">include</span> <span class="hljs-meta-string">&lt;stdio.h&gt;</span></span>
<span class="hljs-function"><span class="hljs-keyword">int</span> <span class="hljs-title">main</span><span class="hljs-params">()</span> </span>{  
    <span class="hljs-keyword">char</span> c;
    <span class="hljs-built_in">printf</span>(<span class="hljs-string">"Enter a character: "</span>);
    <span class="hljs-built_in">scanf</span>(<span class="hljs-string">"%c"</span>, &amp;c);  
    
    <span class="hljs-comment">// %d displays the integer value of a character</span>
    <span class="hljs-comment">// %c displays the actual character</span>
    <span class="hljs-built_in">printf</span>(<span class="hljs-string">"ASCII value of %c = %d"</span>, c, c);
    
    <span class="hljs-keyword">return</span> <span class="hljs-number">0</span>;
}

#include <stdio.h>

int main() {

char c;

printf("Enter a character: ");

scanf("%c", &c);

// %d displays the integer value of a character

// %c displays the actual character

printf("ASCII value of %c = %d", c, c);

return 0;

}

Output


<samp>Enter a character: G
ASCII value of G = 71</samp>

<samp>Enter a character: G

ASCII value of G = 71</samp>

C Program to Compute Quotient and Remainder


<span class="hljs-meta">#<span class="hljs-meta-keyword">include</span> <span class="hljs-meta-string">&lt;stdio.h&gt;</span></span>
<span class="hljs-function"><span class="hljs-keyword">int</span> <span class="hljs-title">main</span><span class="hljs-params">()</span> </span>{
    <span class="hljs-keyword">int</span> dividend, divisor, quotient, remainder;
    <span class="hljs-built_in">printf</span>(<span class="hljs-string">"Enter dividend: "</span>);
    <span class="hljs-built_in">scanf</span>(<span class="hljs-string">"%d"</span>, &amp;dividend);
    <span class="hljs-built_in">printf</span>(<span class="hljs-string">"Enter divisor: "</span>);
    <span class="hljs-built_in">scanf</span>(<span class="hljs-string">"%d"</span>, &amp;divisor);

    <span class="hljs-comment">// Computes quotient</span>
    quotient = dividend / divisor;

    <span class="hljs-comment">// Computes remainder</span>
    remainder = dividend % divisor;

    <span class="hljs-built_in">printf</span>(<span class="hljs-string">"Quotient = %d\n"</span>, quotient);
    <span class="hljs-built_in">printf</span>(<span class="hljs-string">"Remainder = %d"</span>, remainder);
    <span class="hljs-keyword">return</span> <span class="hljs-number">0</span>;
}

#include <stdio.h>

int main() {

int dividend, divisor, quotient, remainder;

printf("Enter dividend: ");

scanf("%d", &dividend);

printf("Enter divisor: ");

scanf("%d", &divisor);

// Computes quotient

quotient = dividend / divisor;

// Computes remainder

remainder = dividend % divisor;

printf("Quotient = %d\n", quotient);

printf("Remainder = %d", remainder);

return 0;

}

Output


<samp>Enter dividend: 25
Enter divisor: 4
Quotient = 6
Remainder = 1 </samp>

<samp>Enter dividend: 25

Enter divisor: 4

Quotient = 6

Remainder = 1 </samp>

C Program to Find the Size of Variables


<span class="hljs-meta">#<span class="hljs-meta-keyword">include</span><span class="hljs-meta-string">&lt;stdio.h&gt;</span></span>
<span class="hljs-function"><span class="hljs-keyword">int</span> <span class="hljs-title">main</span><span class="hljs-params">()</span> </span>{
    <span class="hljs-keyword">int</span> intType;
    <span class="hljs-keyword">float</span> floatType;
    <span class="hljs-keyword">double</span> doubleType;
    <span class="hljs-keyword">char</span> charType;

    <span class="hljs-comment">// sizeof evaluates the size of a variable</span>
    <span class="hljs-built_in">printf</span>(<span class="hljs-string">"Size of int: %zu bytes\n"</span>, <span class="hljs-keyword">sizeof</span>(intType));
    <span class="hljs-built_in">printf</span>(<span class="hljs-string">"Size of float: %zu bytes\n"</span>, <span class="hljs-keyword">sizeof</span>(floatType));
    <span class="hljs-built_in">printf</span>(<span class="hljs-string">"Size of double: %zu bytes\n"</span>, <span class="hljs-keyword">sizeof</span>(doubleType));
    <span class="hljs-built_in">printf</span>(<span class="hljs-string">"Size of char: %zu byte\n"</span>, <span class="hljs-keyword">sizeof</span>(charType));
    
    <span class="hljs-keyword">return</span> <span class="hljs-number">0</span>;
}

#include<stdio.h>

int main() {

int intType;

float floatType;

double doubleType;

char charType;

// sizeof evaluates the size of a variable

printf("Size of int: %zu bytes\n", sizeof(intType));

printf("Size of float: %zu bytes\n", sizeof(floatType));

printf("Size of double: %zu bytes\n", sizeof(doubleType));

printf("Size of char: %zu byte\n", sizeof(charType));

return 0;

}

Output


<samp>Size of int: 4 bytes
Size of float: 4 bytes
Size of double: 8 bytes
Size of char: 1 byte</samp>

<samp>Size of int: 4 bytes

Size of float: 4 bytes

Size of double: 8 bytes

Size of char: 1 byte</samp>

C Program to Find the Size of Variables


<span class="hljs-meta">#<span class="hljs-meta-keyword">include</span><span class="hljs-meta-string">&lt;stdio.h&gt;</span></span>
<span class="hljs-function"><span class="hljs-keyword">int</span> <span class="hljs-title">main</span><span class="hljs-params">()</span> </span>{
    <span class="hljs-keyword">int</span> intType;
    <span class="hljs-keyword">float</span> floatType;
    <span class="hljs-keyword">double</span> doubleType;
    <span class="hljs-keyword">char</span> charType;

    <span class="hljs-comment">// sizeof evaluates the size of a variable</span>
    <span class="hljs-built_in">printf</span>(<span class="hljs-string">"Size of int: %zu bytes\n"</span>, <span class="hljs-keyword">sizeof</span>(intType));
    <span class="hljs-built_in">printf</span>(<span class="hljs-string">"Size of float: %zu bytes\n"</span>, <span class="hljs-keyword">sizeof</span>(floatType));
    <span class="hljs-built_in">printf</span>(<span class="hljs-string">"Size of double: %zu bytes\n"</span>, <span class="hljs-keyword">sizeof</span>(doubleType));
    <span class="hljs-built_in">printf</span>(<span class="hljs-string">"Size of char: %zu byte\n"</span>, <span class="hljs-keyword">sizeof</span>(charType));
    
    <span class="hljs-keyword">return</span> <span class="hljs-number">0</span>;
}

#include<stdio.h>

int main() {

int intType;

float floatType;

double doubleType;

char charType;

// sizeof evaluates the size of a variable

printf("Size of int: %zu bytes\n", sizeof(intType));

printf("Size of float: %zu bytes\n", sizeof(floatType));

printf("Size of double: %zu bytes\n", sizeof(doubleType));

printf("Size of char: %zu byte\n", sizeof(charType));

return 0;

}

Output


<samp>Size of int: 4 bytes
Size of float: 4 bytes
Size of double: 8 bytes
Size of char: 1 byte</samp>

<samp>Size of int: 4 bytes

Size of float: 4 bytes

Size of double: 8 bytes

Size of char: 1 byte</samp>

C Program Using the long keyword


<span class="hljs-meta">#<span class="hljs-meta-keyword">include</span> <span class="hljs-meta-string">&lt;stdio.h&gt;</span></span>
<span class="hljs-function"><span class="hljs-keyword">int</span> <span class="hljs-title">main</span><span class="hljs-params">()</span> </span>{
    <span class="hljs-keyword">int</span> a;
    <span class="hljs-keyword">long</span> b;   <span class="hljs-comment">// equivalent to long int b;</span>
    <span class="hljs-keyword">long</span> <span class="hljs-keyword">long</span> c;  <span class="hljs-comment">// equivalent to long long int c;</span>
    <span class="hljs-keyword">double</span> e;
    <span class="hljs-keyword">long</span> <span class="hljs-keyword">double</span> f;

    <span class="hljs-built_in">printf</span>(<span class="hljs-string">"Size of int = %zu bytes \n"</span>, <span class="hljs-keyword">sizeof</span>(a));
    <span class="hljs-built_in">printf</span>(<span class="hljs-string">"Size of long int = %zu bytes\n"</span>, <span class="hljs-keyword">sizeof</span>(b));
    <span class="hljs-built_in">printf</span>(<span class="hljs-string">"Size of long long int = %zu bytes\n"</span>, <span class="hljs-keyword">sizeof</span>(c));
    <span class="hljs-built_in">printf</span>(<span class="hljs-string">"Size of double = %zu bytes\n"</span>, <span class="hljs-keyword">sizeof</span>(e));
    <span class="hljs-built_in">printf</span>(<span class="hljs-string">"Size of long double = %zu bytes\n"</span>, <span class="hljs-keyword">sizeof</span>(f));
    
    <span class="hljs-keyword">return</span> <span class="hljs-number">0</span>;
}

#include <stdio.h>

int main() {

int a;

long b; // equivalent to long int b;

long long c; // equivalent to long long int c;

double e;

long double f;

printf("Size of int = %zu bytes \n", sizeof(a));

printf("Size of long int = %zu bytes\n", sizeof(b));

printf("Size of long long int = %zu bytes\n", sizeof(c));

printf("Size of double = %zu bytes\n", sizeof(e));

printf("Size of long double = %zu bytes\n", sizeof(f));

return 0;

}

Output


<samp>Size of int = 4 bytes 
Size of long int = 8 bytes
Size of long long int = 8 bytes
Size of double = 8 bytes
Size of long double = 16 bytes
</samp>

<samp>Size of int = 4 bytes

Size of long int = 8 bytes

Size of long long int = 8 bytes

Size of double = 8 bytes

Size of long double = 16 bytes

</samp>

C Swap Numbers Using Temporary Variable


<span class="hljs-meta">#<span class="hljs-meta-keyword">include</span><span class="hljs-meta-string">&lt;stdio.h&gt;</span></span>
<span class="hljs-function"><span class="hljs-keyword">int</span> <span class="hljs-title">main</span><span class="hljs-params">()</span> </span>{
      <span class="hljs-keyword">double</span> first, second, temp;
      <span class="hljs-built_in">printf</span>(<span class="hljs-string">"Enter first number: "</span>);
      <span class="hljs-built_in">scanf</span>(<span class="hljs-string">"%lf"</span>, &amp;first);
      <span class="hljs-built_in">printf</span>(<span class="hljs-string">"Enter second number: "</span>);
      <span class="hljs-built_in">scanf</span>(<span class="hljs-string">"%lf"</span>, &amp;second);

      <span class="hljs-comment">// Value of first is assigned to temp</span>
      temp = first;

      <span class="hljs-comment">// Value of second is assigned to first</span>
      first = second;

      <span class="hljs-comment">// Value of temp (initial value of first) is assigned to second</span>
      second = temp;

      <span class="hljs-built_in">printf</span>(<span class="hljs-string">"\nAfter swapping, firstNumber = %.2lf\n"</span>, first);
      <span class="hljs-built_in">printf</span>(<span class="hljs-string">"After swapping, secondNumber = %.2lf"</span>, second);
      <span class="hljs-keyword">return</span> <span class="hljs-number">0</span>;
}

#include<stdio.h>

int main() {

double first, second, temp;

printf("Enter first number: ");

scanf("%lf", &first);

printf("Enter second number: ");

scanf("%lf", &second);

// Value of first is assigned to temp

temp = first;

// Value of second is assigned to first

first = second;

// Value of temp (initial value of first) is assigned to second

second = temp;

printf("\nAfter swapping, firstNumber = %.2lf\n", first);

printf("After swapping, secondNumber = %.2lf", second);

return 0;

}

Output


<samp>Enter first number: 1.20
Enter second number: 2.45

After swapping, firstNumber = 2.45
After swapping, secondNumber = 1.20</samp>

<samp>Enter first number: 1.20

Enter second number: 2.45

After swapping, firstNumber = 2.45

After swapping, secondNumber = 1.20</samp>

C Program to Check Even or Odd


<span class="hljs-meta">#<span class="hljs-meta-keyword">include</span> <span class="hljs-meta-string">&lt;stdio.h&gt;</span></span>
<span class="hljs-function"><span class="hljs-keyword">int</span> <span class="hljs-title">main</span><span class="hljs-params">()</span> </span>{
    <span class="hljs-keyword">int</span> num;
    <span class="hljs-built_in">printf</span>(<span class="hljs-string">"Enter an integer: "</span>);
    <span class="hljs-built_in">scanf</span>(<span class="hljs-string">"%d"</span>, &amp;num);

    <span class="hljs-comment">// True if num is perfectly divisible by 2</span>
    <span class="hljs-keyword">if</span>(num % <span class="hljs-number">2</span> == <span class="hljs-number">0</span>)
        <span class="hljs-built_in">printf</span>(<span class="hljs-string">"%d is even."</span>, num);
    <span class="hljs-keyword">else</span>
        <span class="hljs-built_in">printf</span>(<span class="hljs-string">"%d is odd."</span>, num);
    
    <span class="hljs-keyword">return</span> <span class="hljs-number">0</span>;
}

#include <stdio.h>

int main() {

int num;

printf("Enter an integer: ");

scanf("%d", &num);

// True if num is perfectly divisible by 2

if(num % 2 == 0)

printf("%d is even.", num);

else

printf("%d is odd.", num);

return 0;

}

Output


<samp>Enter an integer: -7
-7 is odd.</samp>

<samp>Enter an integer: -7

-7 is odd.</samp>

C Program to Check Vowel or consonant


<span class="hljs-meta">#<span class="hljs-meta-keyword">include</span> <span class="hljs-meta-string">&lt;stdio.h&gt;</span></span>
<span class="hljs-function"><span class="hljs-keyword">int</span> <span class="hljs-title">main</span><span class="hljs-params">()</span> </span>{
    <span class="hljs-keyword">char</span> c;
    <span class="hljs-keyword">int</span> lowercase_vowel, uppercase_vowel;
    <span class="hljs-built_in">printf</span>(<span class="hljs-string">"Enter an alphabet: "</span>);
    <span class="hljs-built_in">scanf</span>(<span class="hljs-string">"%c"</span>, &amp;c);

    <span class="hljs-comment">// evaluates to 1 if variable c is a lowercase vowel</span>
    lowercase_vowel = (c == <span class="hljs-string">'a'</span> || c == <span class="hljs-string">'e'</span> || c == <span class="hljs-string">'i'</span> || c == <span class="hljs-string">'o'</span> || c == <span class="hljs-string">'u'</span>);

    <span class="hljs-comment">// evaluates to 1 if variable c is a uppercase vowel</span>
    uppercase_vowel = (c == <span class="hljs-string">'A'</span> || c == <span class="hljs-string">'E'</span> || c == <span class="hljs-string">'I'</span> || c == <span class="hljs-string">'O'</span> || c == <span class="hljs-string">'U'</span>);

    <span class="hljs-comment">// evaluates to 1 (true) if c is a vowel</span>
    <span class="hljs-keyword">if</span> (lowercase_vowel || uppercase_vowel)
        <span class="hljs-built_in">printf</span>(<span class="hljs-string">"%c is a vowel."</span>, c);
    <span class="hljs-keyword">else</span>
        <span class="hljs-built_in">printf</span>(<span class="hljs-string">"%c is a consonant."</span>, c);
    <span class="hljs-keyword">return</span> <span class="hljs-number">0</span>;
}

#include <stdio.h>

int main() {

char c;

int lowercase_vowel, uppercase_vowel;

printf("Enter an alphabet: ");

scanf("%c", &c);

// evaluates to 1 if variable c is a lowercase vowel

lowercase_vowel = (c == 'a' || c == 'e' || c == 'i' || c == 'o' || c == 'u');

// evaluates to 1 if variable c is a uppercase vowel

uppercase_vowel = (c == 'A' || c == 'E' || c == 'I' || c == 'O' || c == 'U');

// evaluates to 1 (true) if c is a vowel

if (lowercase_vowel || uppercase_vowel)

printf("%c is a vowel.", c);

else

printf("%c is a consonant.", c);

return 0;

}

Output


<samp>Enter an alphabet: G
G is a consonant.</samp>

<samp>Enter an alphabet: G

G is a consonant.</samp>

C Program to Find the Largest Number Among Three Numbers

Example 1: Using if Statement


<span class="hljs-meta">#<span class="hljs-meta-keyword">include</span> <span class="hljs-meta-string">&lt;stdio.h&gt;</span></span>
<span class="hljs-function"><span class="hljs-keyword">int</span> <span class="hljs-title">main</span><span class="hljs-params">()</span> </span>{
    <span class="hljs-keyword">double</span> n1, n2, n3;
    <span class="hljs-built_in">printf</span>(<span class="hljs-string">"Enter three different numbers: "</span>);
    <span class="hljs-built_in">scanf</span>(<span class="hljs-string">"%lf %lf %lf"</span>, &amp;n1, &amp;n2, &amp;n3);

    <span class="hljs-comment">// if n1 is greater than both n2 and n3, n1 is the largest</span>
    <span class="hljs-keyword">if</span> (n1 &gt;= n2 &amp;&amp; n1 &gt;= n3)
        <span class="hljs-built_in">printf</span>(<span class="hljs-string">"%.2f is the largest number."</span>, n1);

    <span class="hljs-comment">// if n2 is greater than both n1 and n3, n2 is the largest</span>
    <span class="hljs-keyword">if</span> (n2 &gt;= n1 &amp;&amp; n2 &gt;= n3)
        <span class="hljs-built_in">printf</span>(<span class="hljs-string">"%.2f is the largest number."</span>, n2);

    <span class="hljs-comment">// if n3 is greater than both n1 and n2, n3 is the largest</span>
    <span class="hljs-keyword">if</span> (n3 &gt;= n1 &amp;&amp; n3 &gt;= n2)
        <span class="hljs-built_in">printf</span>(<span class="hljs-string">"%.2f is the largest number."</span>, n3);

    <span class="hljs-keyword">return</span> <span class="hljs-number">0</span>;
}

#include <stdio.h>

int main() {

double n1, n2, n3;

printf("Enter three different numbers: ");

scanf("%lf %lf %lf", &n1, &n2, &n3);

// if n1 is greater than both n2 and n3, n1 is the largest

if (n1 >= n2 && n1 >= n3)

printf("%.2f is the largest number.", n1);

// if n2 is greater than both n1 and n3, n2 is the largest

if (n2 >= n1 && n2 >= n3)

printf("%.2f is the largest number.", n2);

// if n3 is greater than both n1 and n2, n3 is the largest

if (n3 >= n1 && n3 >= n2)

printf("%.2f is the largest number.", n3);

return 0;

}

Example 2: Using if…else Ladder


<span class="hljs-meta">#<span class="hljs-meta-keyword">include</span> <span class="hljs-meta-string">&lt;stdio.h&gt;</span></span>
<span class="hljs-function"><span class="hljs-keyword">int</span> <span class="hljs-title">main</span><span class="hljs-params">()</span> </span>{
    <span class="hljs-keyword">double</span> n1, n2, n3;
    <span class="hljs-built_in">printf</span>(<span class="hljs-string">"Enter three numbers: "</span>);
    <span class="hljs-built_in">scanf</span>(<span class="hljs-string">"%lf %lf %lf"</span>, &amp;n1, &amp;n2, &amp;n3);

    <span class="hljs-comment">// if n1 is greater than both n2 and n3, n1 is the largest</span>
    <span class="hljs-keyword">if</span> (n1 &gt;= n2 &amp;&amp; n1 &gt;= n3)
        <span class="hljs-built_in">printf</span>(<span class="hljs-string">"%.2lf is the largest number."</span>, n1);

    <span class="hljs-comment">// if n2 is greater than both n1 and n3, n2 is the largest</span>
    <span class="hljs-keyword">else</span> <span class="hljs-keyword">if</span> (n2 &gt;= n1 &amp;&amp; n2 &gt;= n3)
        <span class="hljs-built_in">printf</span>(<span class="hljs-string">"%.2lf is the largest number."</span>, n2);

    <span class="hljs-comment">// if both above conditions are false, n3 is the largest</span>
    <span class="hljs-keyword">else</span>
        <span class="hljs-built_in">printf</span>(<span class="hljs-string">"%.2lf is the largest number."</span>, n3);

    <span class="hljs-keyword">return</span> <span class="hljs-number">0</span>;
}

#include <stdio.h>

int main() {

double n1, n2, n3;

printf("Enter three numbers: ");

scanf("%lf %lf %lf", &n1, &n2, &n3);

// if n1 is greater than both n2 and n3, n1 is the largest

if (n1 >= n2 && n1 >= n3)

printf("%.2lf is the largest number.", n1);

// if n2 is greater than both n1 and n3, n2 is the largest

else if (n2 >= n1 && n2 >= n3)

printf("%.2lf is the largest number.", n2);

// if both above conditions are false, n3 is the largest

else

printf("%.2lf is the largest number.", n3);

return 0;

}

Example 3: Using Nested if…else


<span class="hljs-meta">#<span class="hljs-meta-keyword">include</span> <span class="hljs-meta-string">&lt;stdio.h&gt;</span></span>
<span class="hljs-function"><span class="hljs-keyword">int</span> <span class="hljs-title">main</span><span class="hljs-params">()</span> </span>{
    <span class="hljs-keyword">double</span> n1, n2, n3;
    <span class="hljs-built_in">printf</span>(<span class="hljs-string">"Enter three numbers: "</span>);
    <span class="hljs-built_in">scanf</span>(<span class="hljs-string">"%lf %lf %lf"</span>, &amp;n1, &amp;n2, &amp;n3);

    <span class="hljs-keyword">if</span> (n1 &gt;= n2) {
        <span class="hljs-keyword">if</span> (n1 &gt;= n3)
            <span class="hljs-built_in">printf</span>(<span class="hljs-string">"%.2lf is the largest number."</span>, n1);
        <span class="hljs-keyword">else</span>
            <span class="hljs-built_in">printf</span>(<span class="hljs-string">"%.2lf is the largest number."</span>, n3);
    } <span class="hljs-keyword">else</span> {
        <span class="hljs-keyword">if</span> (n2 &gt;= n3)
            <span class="hljs-built_in">printf</span>(<span class="hljs-string">"%.2lf is the largest number."</span>, n2);
        <span class="hljs-keyword">else</span>
            <span class="hljs-built_in">printf</span>(<span class="hljs-string">"%.2lf is the largest number."</span>, n3);
    }

    <span class="hljs-keyword">return</span> <span class="hljs-number">0</span>;
}

#include <stdio.h>

int main() {

double n1, n2, n3;

printf("Enter three numbers: ");

scanf("%lf %lf %lf", &n1, &n2, &n3);

if (n1 >= n2) {

if (n1 >= n3)

printf("%.2lf is the largest number.", n1);

else

printf("%.2lf is the largest number.", n3);

} else {

if (n2 >= n3)

printf("%.2lf is the largest number.", n2);

else

printf("%.2lf is the largest number.", n3);

}

return 0;

}

Output:


<samp>Enter three numbers: -4.5
3.9
5.6
5.60 is the largest number.</samp>

<samp>Enter three numbers: -4.5

3.9

5.6

5.60 is the largest number.</samp>

C Program to Find Roots of a Quadratic Equation


<span class="hljs-meta">#<span class="hljs-meta-keyword">include</span> <span class="hljs-meta-string">&lt;math.h&gt;</span></span>
<span class="hljs-meta">#<span class="hljs-meta-keyword">include</span> <span class="hljs-meta-string">&lt;stdio.h&gt;</span></span>
<span class="hljs-function"><span class="hljs-keyword">int</span> <span class="hljs-title">main</span><span class="hljs-params">()</span> </span>{
    <span class="hljs-keyword">double</span> a, b, c, discriminant, root1, root2, realPart, imagPart;
    <span class="hljs-built_in">printf</span>(<span class="hljs-string">"Enter coefficients a, b and c: "</span>);
    <span class="hljs-built_in">scanf</span>(<span class="hljs-string">"%lf %lf %lf"</span>, &amp;a, &amp;b, &amp;c);

    discriminant = b * b - <span class="hljs-number">4</span> * a * c;

    <span class="hljs-comment">// condition for real and different roots</span>
    <span class="hljs-keyword">if</span> (discriminant &gt; <span class="hljs-number">0</span>) {
        root1 = (-b + <span class="hljs-built_in">sqrt</span>(discriminant)) / (<span class="hljs-number">2</span> * a);
        root2 = (-b - <span class="hljs-built_in">sqrt</span>(discriminant)) / (<span class="hljs-number">2</span> * a);
        <span class="hljs-built_in">printf</span>(<span class="hljs-string">"root1 = %.2lf and root2 = %.2lf"</span>, root1, root2);
    }

    <span class="hljs-comment">// condition for real and equal roots</span>
    <span class="hljs-keyword">else</span> <span class="hljs-keyword">if</span> (discriminant == <span class="hljs-number">0</span>) {
        root1 = root2 = -b / (<span class="hljs-number">2</span> * a);
        <span class="hljs-built_in">printf</span>(<span class="hljs-string">"root1 = root2 = %.2lf;"</span>, root1);
    }

    <span class="hljs-comment">// if roots are not real</span>
    <span class="hljs-keyword">else</span> {
        realPart = -b / (<span class="hljs-number">2</span> * a);
        imagPart = <span class="hljs-built_in">sqrt</span>(-discriminant) / (<span class="hljs-number">2</span> * a);
        <span class="hljs-built_in">printf</span>(<span class="hljs-string">"root1 = %.2lf+%.2lfi and root2 = %.2f-%.2fi"</span>, realPart, imagPart, realPart, imagPart);
    }

    <span class="hljs-keyword">return</span> <span class="hljs-number">0</span>;
}

#include <math.h>

#include <stdio.h>

int main() {

double a, b, c, discriminant, root1, root2, realPart, imagPart;

printf("Enter coefficients a, b and c: ");

scanf("%lf %lf %lf", &a, &b, &c);

discriminant = b * b - 4 * a * c;

// condition for real and different roots

if (discriminant > 0) {

root1 = (-b + sqrt(discriminant)) / (2 * a);

root2 = (-b - sqrt(discriminant)) / (2 * a);

printf("root1 = %.2lf and root2 = %.2lf", root1, root2);

}

// condition for real and equal roots

else if (discriminant == 0) {

root1 = root2 = -b / (2 * a);

printf("root1 = root2 = %.2lf;", root1);

}

// if roots are not real

else {

realPart = -b / (2 * a);

imagPart = sqrt(-discriminant) / (2 * a);

printf("root1 = %.2lf+%.2lfi and root2 = %.2f-%.2fi", realPart, imagPart, realPart, imagPart);

}

return 0;

}

Output


<samp>Enter coefficients a, b and c: 2.3
4
5.6
root1 = -0.87+1.30i and root2 = -0.87-1.30i</samp>

<samp>Enter coefficients a, b and c: 2.3

5.6

root1 = -0.87+1.30i and root2 = -0.87-1.30i</samp>

C Program to Check Leap Year


<span class="hljs-meta">#<span class="hljs-meta-keyword">include</span> <span class="hljs-meta-string">&lt;stdio.h&gt;</span></span>
<span class="hljs-function"><span class="hljs-keyword">int</span> <span class="hljs-title">main</span><span class="hljs-params">()</span> </span>{
   <span class="hljs-keyword">int</span> year;
   <span class="hljs-built_in">printf</span>(<span class="hljs-string">"Enter a year: "</span>);
   <span class="hljs-built_in">scanf</span>(<span class="hljs-string">"%d"</span>, &amp;year);

   <span class="hljs-comment">// leap year if perfectly visible by 400</span>
   <span class="hljs-keyword">if</span> (year % <span class="hljs-number">400</span> == <span class="hljs-number">0</span>) {
      <span class="hljs-built_in">printf</span>(<span class="hljs-string">"%d is a leap year."</span>, year);
   }
   <span class="hljs-comment">// not a leap year if visible by 100</span>
   <span class="hljs-comment">// but not divisible by 400</span>
   <span class="hljs-keyword">else</span> <span class="hljs-keyword">if</span> (year % <span class="hljs-number">100</span> == <span class="hljs-number">0</span>) {
      <span class="hljs-built_in">printf</span>(<span class="hljs-string">"%d is not a leap year."</span>, year);
   }
   <span class="hljs-comment">// leap year if not divisible by 100</span>
   <span class="hljs-comment">// but divisible by 4</span>
   <span class="hljs-keyword">else</span> <span class="hljs-keyword">if</span> (year % <span class="hljs-number">4</span> == <span class="hljs-number">0</span>) {
      <span class="hljs-built_in">printf</span>(<span class="hljs-string">"%d is a leap year."</span>, year);
   }
   <span class="hljs-comment">// all other years are not leap year</span>
   <span class="hljs-keyword">else</span> {
      <span class="hljs-built_in">printf</span>(<span class="hljs-string">"%d is not a leap year."</span>, year);
   }

   <span class="hljs-keyword">return</span> <span class="hljs-number">0</span>;
}

#include <stdio.h>

int main() {

int year;

printf("Enter a year: ");

scanf("%d", &year);

// leap year if perfectly visible by 400

if (year % 400 == 0) {

printf("%d is a leap year.", year);

}

// not a leap year if visible by 100

// but not divisible by 400

else if (year % 100 == 0) {

printf("%d is not a leap year.", year);

}

// leap year if not divisible by 100

// but divisible by 4

else if (year % 4 == 0) {

printf("%d is a leap year.", year);

}

// all other years are not leap year

else {

printf("%d is not a leap year.", year);

}

return 0;

}

Output 1


<samp>Enter a year: 1900
1900 is not a leap year.
</samp>

<samp>Enter a year: 1900

1900 is not a leap year.

</samp>

Output 2


<samp>Enter a year: 2012
2012 is a leap year.</samp>

<samp>Enter a year: 2012

2012 is a leap year.</samp>

C Program to Check Positive or Negative Using if…else


<span class="hljs-meta">#<span class="hljs-meta-keyword">include</span> <span class="hljs-meta-string">&lt;stdio.h&gt;</span></span>
<span class="hljs-function"><span class="hljs-keyword">int</span> <span class="hljs-title">main</span><span class="hljs-params">()</span> </span>{
    <span class="hljs-keyword">double</span> num;
    <span class="hljs-built_in">printf</span>(<span class="hljs-string">"Enter a number: "</span>);
    <span class="hljs-built_in">scanf</span>(<span class="hljs-string">"%lf"</span>, &amp;num);
    <span class="hljs-keyword">if</span> (num &lt;= <span class="hljs-number">0.0</span>) {
        <span class="hljs-keyword">if</span> (num == <span class="hljs-number">0.0</span>)
            <span class="hljs-built_in">printf</span>(<span class="hljs-string">"You entered 0."</span>);
        <span class="hljs-keyword">else</span>
            <span class="hljs-built_in">printf</span>(<span class="hljs-string">"You entered a negative number."</span>);
    } <span class="hljs-keyword">else</span>
        <span class="hljs-built_in">printf</span>(<span class="hljs-string">"You entered a positive number."</span>);
    <span class="hljs-keyword">return</span> <span class="hljs-number">0</span>;
}

#include <stdio.h>

int main() {

double num;

printf("Enter a number: ");

scanf("%lf", &num);

if (num <= 0.0) {

if (num == 0.0)

printf("You entered 0.");

else

printf("You entered a negative number.");

} else

printf("You entered a positive number.");

return 0;

}

You can also solve this problem using nested if else statement.

C Program to Check Positive or Negative Using Nested if…else


<span class="hljs-meta">#<span class="hljs-meta-keyword">include</span> <span class="hljs-meta-string">&lt;stdio.h&gt;</span></span>
<span class="hljs-function"><span class="hljs-keyword">int</span> <span class="hljs-title">main</span><span class="hljs-params">()</span> </span>{
    <span class="hljs-keyword">double</span> num;
    <span class="hljs-built_in">printf</span>(<span class="hljs-string">"Enter a number: "</span>);
    <span class="hljs-built_in">scanf</span>(<span class="hljs-string">"%lf"</span>, &amp;num);

    <span class="hljs-keyword">if</span> (num &lt; <span class="hljs-number">0.0</span>)
        <span class="hljs-built_in">printf</span>(<span class="hljs-string">"You entered a negative number."</span>);
    <span class="hljs-keyword">else</span> <span class="hljs-keyword">if</span> (num &gt; <span class="hljs-number">0.0</span>)
        <span class="hljs-built_in">printf</span>(<span class="hljs-string">"You entered a positive number."</span>);
    <span class="hljs-keyword">else</span>
        <span class="hljs-built_in">printf</span>(<span class="hljs-string">"You entered 0."</span>);

    <span class="hljs-keyword">return</span> <span class="hljs-number">0</span>;
}

#include <stdio.h>

int main() {

double num;

printf("Enter a number: ");

scanf("%lf", &num);

if (num < 0.0)

printf("You entered a negative number.");

else if (num > 0.0)

printf("You entered a positive number.");

else

printf("You entered 0.");

return 0;

}

Output 1


<samp>Enter a number: 12.3
You entered a positive number.
</samp>

<samp>Enter a number: 12.3

You entered a positive number.

</samp>

Output 2


<samp>Enter a number: 0
You entered 0.</samp>

<samp>Enter a number: 0

You entered 0.</samp>

C Program to Check Alphabet


<span class="hljs-meta">#<span class="hljs-meta-keyword">include</span> <span class="hljs-meta-string">&lt;stdio.h&gt;</span></span>
<span class="hljs-function"><span class="hljs-keyword">int</span> <span class="hljs-title">main</span><span class="hljs-params">()</span> </span>{
    <span class="hljs-keyword">char</span> c;
    <span class="hljs-built_in">printf</span>(<span class="hljs-string">"Enter a character: "</span>);
    <span class="hljs-built_in">scanf</span>(<span class="hljs-string">"%c"</span>, &amp;c);

    <span class="hljs-keyword">if</span> ((c &gt;= <span class="hljs-string">'a'</span> &amp;&amp; c &lt;= <span class="hljs-string">'z'</span>) || (c &gt;= <span class="hljs-string">'A'</span> &amp;&amp; c &lt;= <span class="hljs-string">'Z'</span>))
        <span class="hljs-built_in">printf</span>(<span class="hljs-string">"%c is an alphabet."</span>, c);
    <span class="hljs-keyword">else</span>
        <span class="hljs-built_in">printf</span>(<span class="hljs-string">"%c is not an alphabet."</span>, c);

    <span class="hljs-keyword">return</span> <span class="hljs-number">0</span>;
}

#include <stdio.h>

int main() {

char c;

printf("Enter a character: ");

scanf("%c", &c);

if ((c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z'))

printf("%c is an alphabet.", c);

else

printf("%c is not an alphabet.", c);

return 0;

}

Output


<samp>Enter a character: *
* is not an alphabet</samp>

<samp>Enter a character: *

* is not an alphabet</samp>

C Program to Sum of Natural Numbers Using for Loop


<span class="hljs-meta">#<span class="hljs-meta-keyword">include</span> <span class="hljs-meta-string">&lt;stdio.h&gt;</span></span>
<span class="hljs-function"><span class="hljs-keyword">int</span> <span class="hljs-title">main</span><span class="hljs-params">()</span> </span>{
    <span class="hljs-keyword">int</span> n, i, sum = <span class="hljs-number">0</span>;

    <span class="hljs-built_in">printf</span>(<span class="hljs-string">"Enter a positive integer: "</span>);
    <span class="hljs-built_in">scanf</span>(<span class="hljs-string">"%d"</span>, &amp;n);

    <span class="hljs-keyword">for</span> (i = <span class="hljs-number">1</span>; i &lt;= n; ++i) {
        sum += i;
    }

    <span class="hljs-built_in">printf</span>(<span class="hljs-string">"Sum = %d"</span>, sum);
    <span class="hljs-keyword">return</span> <span class="hljs-number">0</span>;
}

#include <stdio.h>

int main() {

int n, i, sum = 0;

printf("Enter a positive integer: ");

scanf("%d", &n);

for (i = 1; i <= n; ++i) {

sum += i;

}

printf("Sum = %d", sum);

return 0;

}

The above program takes input from the user and stores it in the variable n. Then, for loop is used to calculate the sum up to n.

C Program to Sum of Natural Numbers Using while Loop


<span class="hljs-meta">#<span class="hljs-meta-keyword">include</span> <span class="hljs-meta-string">&lt;stdio.h&gt;</span></span>
<span class="hljs-function"><span class="hljs-keyword">int</span> <span class="hljs-title">main</span><span class="hljs-params">()</span> </span>{
    <span class="hljs-keyword">int</span> n, i, sum = <span class="hljs-number">0</span>;
    <span class="hljs-built_in">printf</span>(<span class="hljs-string">"Enter a positive integer: "</span>);
    <span class="hljs-built_in">scanf</span>(<span class="hljs-string">"%d"</span>, &amp;n);
    i = <span class="hljs-number">1</span>;

    <span class="hljs-keyword">while</span> (i &lt;= n) {
        sum += i;
        ++i;
    }

    <span class="hljs-built_in">printf</span>(<span class="hljs-string">"Sum = %d"</span>, sum);
    <span class="hljs-keyword">return</span> <span class="hljs-number">0</span>;
}

#include <stdio.h>

int main() {

int n, i, sum = 0;

printf("Enter a positive integer: ");

scanf("%d", &n);

i = 1;

while (i <= n) {

sum += i;

++i;

}

printf("Sum = %d", sum);

return 0;

}

Output


<samp>Enter a positive integer: 100
Sum = 5050
</samp>

<samp>Enter a positive integer: 100

Sum = 5050

</samp>

In both programs, the loop is iterated n number of times. And, in each iteration, the value of i is added to sum and i is incremented by 1.

Though both programs are technically correct, it is better to use for loop in this case. It’s because the number of iterations is known.

The above programs don’t work properly if the user enters a negative integer. Here is a little modification to the above program where we keep taking input from the user until a positive integer is entered.

C Program to Read Input Until a Positive Integer is Entered


<span class="hljs-meta">#<span class="hljs-meta-keyword">include</span> <span class="hljs-meta-string">&lt;stdio.h&gt;</span></span>
<span class="hljs-function"><span class="hljs-keyword">int</span> <span class="hljs-title">main</span><span class="hljs-params">()</span> </span>{
    <span class="hljs-keyword">int</span> n, i, sum = <span class="hljs-number">0</span>;

    <span class="hljs-keyword">do</span> {
        <span class="hljs-built_in">printf</span>(<span class="hljs-string">"Enter a positive integer: "</span>);
        <span class="hljs-built_in">scanf</span>(<span class="hljs-string">"%d"</span>, &amp;n);
    } <span class="hljs-keyword">while</span> (n &lt;= <span class="hljs-number">0</span>);

    <span class="hljs-keyword">for</span> (i = <span class="hljs-number">1</span>; i &lt;= n; ++i) {
        sum += i;
    }

    <span class="hljs-built_in">printf</span>(<span class="hljs-string">"Sum = %d"</span>, sum);
    <span class="hljs-keyword">return</span> <span class="hljs-number">0</span>;
}

#include <stdio.h>

int main() {

int n, i, sum = 0;

do {

printf("Enter a positive integer: ");

scanf("%d", &n);

} while (n <= 0);

for (i = 1; i <= n; ++i) {

sum += i;

}

printf("Sum = %d", sum);

return 0;

}

C Program to Find Factorial of a Number


<span class="hljs-meta">#<span class="hljs-meta-keyword">include</span> <span class="hljs-meta-string">&lt;stdio.h&gt;</span></span>
<span class="hljs-function"><span class="hljs-keyword">int</span> <span class="hljs-title">main</span><span class="hljs-params">()</span> </span>{
    <span class="hljs-keyword">int</span> n, i;
    <span class="hljs-keyword">unsigned</span> <span class="hljs-keyword">long</span> <span class="hljs-keyword">long</span> fact = <span class="hljs-number">1</span>;
    <span class="hljs-built_in">printf</span>(<span class="hljs-string">"Enter an integer: "</span>);
    <span class="hljs-built_in">scanf</span>(<span class="hljs-string">"%d"</span>, &amp;n);

    <span class="hljs-comment">// shows error if the user enters a negative integer</span>
    <span class="hljs-keyword">if</span> (n &lt; <span class="hljs-number">0</span>)
        <span class="hljs-built_in">printf</span>(<span class="hljs-string">"Error! Factorial of a negative number doesn't exist."</span>);
    <span class="hljs-keyword">else</span> {
        <span class="hljs-keyword">for</span> (i = <span class="hljs-number">1</span>; i &lt;= n; ++i) {
            fact *= i;
        }
        <span class="hljs-built_in">printf</span>(<span class="hljs-string">"Factorial of %d = %llu"</span>, n, fact);
    }

    <span class="hljs-keyword">return</span> <span class="hljs-number">0</span>;
}

#include <stdio.h>

int main() {

int n, i;

unsigned long long fact = 1;

printf("Enter an integer: ");

scanf("%d", &n);

// shows error if the user enters a negative integer

if (n < 0)

printf("Error! Factorial of a negative number doesn't exist.");

else {

for (i = 1; i <= n; ++i) {

fact *= i;

}

printf("Factorial of %d = %llu", n, fact);

}

return 0;

}

Output


<samp>Enter an integer: 10
Factorial of 10 = 3628800</samp>

<samp>Enter an integer: 10

Factorial of 10 = 3628800</samp>

C Program to Print Multiplication Table Up to 10


<span class="hljs-meta">#<span class="hljs-meta-keyword">include</span> <span class="hljs-meta-string">&lt;stdio.h&gt;</span></span>
<span class="hljs-function"><span class="hljs-keyword">int</span> <span class="hljs-title">main</span><span class="hljs-params">()</span> </span>{
    <span class="hljs-keyword">int</span> n, i;
    <span class="hljs-built_in">printf</span>(<span class="hljs-string">"Enter an integer: "</span>);
    <span class="hljs-built_in">scanf</span>(<span class="hljs-string">"%d"</span>, &amp;n);
    <span class="hljs-keyword">for</span> (i = <span class="hljs-number">1</span>; i &lt;= <span class="hljs-number">10</span>; ++i) {
        <span class="hljs-built_in">printf</span>(<span class="hljs-string">"%d * %d = %d \n"</span>, n, i, n * i);
    }
    <span class="hljs-keyword">return</span> <span class="hljs-number">0</span>;
}

#include <stdio.h>

int main() {

int n, i;

printf("Enter an integer: ");

scanf("%d", &n);

for (i = 1; i <= 10; ++i) {

printf("%d * %d = %d \n", n, i, n * i);

}

return 0;

}

Output


<samp>Enter an integer: 9
9 * 1 = 9
9 * 2 = 18
9 * 3 = 27
9 * 4 = 36
9 * 5 = 45
9 * 6 = 54
9 * 7 = 63
9 * 8 = 72
9 * 9 = 81
9 * 10 = 90</samp>

<samp>Enter an integer: 9

9 * 1 = 9

9 * 2 = 18

9 * 3 = 27

9 * 4 = 36

9 * 5 = 45

9 * 6 = 54

9 * 7 = 63

9 * 8 = 72

9 * 9 = 81

9 * 10 = 90</samp>

C Program to Print Multiplication Table Up to a range


<span class="hljs-meta">#<span class="hljs-meta-keyword">include</span> <span class="hljs-meta-string">&lt;stdio.h&gt;</span></span>
<span class="hljs-function"><span class="hljs-keyword">int</span> <span class="hljs-title">main</span><span class="hljs-params">()</span> </span>{
    <span class="hljs-keyword">int</span> n, i, range;
    <span class="hljs-built_in">printf</span>(<span class="hljs-string">"Enter an integer: "</span>);
    <span class="hljs-built_in">scanf</span>(<span class="hljs-string">"%d"</span>, &amp;n);
    <span class="hljs-built_in">printf</span>(<span class="hljs-string">"Enter the range: "</span>);
    <span class="hljs-built_in">scanf</span>(<span class="hljs-string">"%d"</span>, &amp;range);
    <span class="hljs-keyword">for</span> (i = <span class="hljs-number">1</span>; i &lt;= range; ++i) {
        <span class="hljs-built_in">printf</span>(<span class="hljs-string">"%d * %d = %d \n"</span>, n, i, n * i);
    }
    <span class="hljs-keyword">return</span> <span class="hljs-number">0</span>;
}

#include <stdio.h>

int main() {

int n, i, range;

printf("Enter an integer: ");

scanf("%d", &n);

printf("Enter the range: ");

scanf("%d", &range);

for (i = 1; i <= range; ++i) {

printf("%d * %d = %d \n", n, i, n * i);

}

return 0;

}

Output


<samp>Enter an integer: 12
Enter the range: 8
12 * 1 = 12 
12 * 2 = 24 
12 * 3 = 36 
12 * 4 = 48 
12 * 5 = 60 
12 * 6 = 72 
12 * 7 = 84 
12 * 8 = 96 </samp>

<samp>Enter an integer: 12

Enter the range: 8

12 * 1 = 12

12 * 2 = 24

12 * 3 = 36

12 * 4 = 48

12 * 5 = 60

12 * 6 = 72

12 * 7 = 84

12 * 8 = 96 </samp>

C Program to Print Fibonacci Series up to n terms


<span class="hljs-meta">#<span class="hljs-meta-keyword">include</span> <span class="hljs-meta-string">&lt;stdio.h&gt;</span></span>
<span class="hljs-function"><span class="hljs-keyword">int</span> <span class="hljs-title">main</span><span class="hljs-params">()</span> </span>{
    <span class="hljs-keyword">int</span> i, n, t1 = <span class="hljs-number">0</span>, t2 = <span class="hljs-number">1</span>, nextTerm;
    <span class="hljs-built_in">printf</span>(<span class="hljs-string">"Enter the number of terms: "</span>);
    <span class="hljs-built_in">scanf</span>(<span class="hljs-string">"%d"</span>, &amp;n);
    <span class="hljs-built_in">printf</span>(<span class="hljs-string">"Fibonacci Series: "</span>);

    <span class="hljs-keyword">for</span> (i = <span class="hljs-number">1</span>; i &lt;= n; ++i) {
        <span class="hljs-built_in">printf</span>(<span class="hljs-string">"%d, "</span>, t1);
        nextTerm = t1 + t2;
        t1 = t2;
        t2 = nextTerm;
    }

    <span class="hljs-keyword">return</span> <span class="hljs-number">0</span>;
}

#include <stdio.h>

int main() {

int i, n, t1 = 0, t2 = 1, nextTerm;

printf("Enter the number of terms: ");

scanf("%d", &n);

printf("Fibonacci Series: ");

for (i = 1; i <= n; ++i) {

printf("%d, ", t1);

nextTerm = t1 + t2;

t1 = t2;

t2 = nextTerm;

}

return 0;

}

Output


<samp>Enter the number of terms: 10
Fibonacci Series: 0, 1, 1, 2, 3, 5, 8, 13, 21, 34, </samp>

<samp>Enter the number of terms: 10

Fibonacci Series: 0, 1, 1, 2, 3, 5, 8, 13, 21, 34, </samp>

C Program to Print Fibonacci Sequence Up to a Certain Number


<span class="hljs-meta">#<span class="hljs-meta-keyword">include</span> <span class="hljs-meta-string">&lt;stdio.h&gt;</span></span>
<span class="hljs-function"><span class="hljs-keyword">int</span> <span class="hljs-title">main</span><span class="hljs-params">()</span> </span>{
    <span class="hljs-keyword">int</span> t1 = <span class="hljs-number">0</span>, t2 = <span class="hljs-number">1</span>, nextTerm = <span class="hljs-number">0</span>, n;
    <span class="hljs-built_in">printf</span>(<span class="hljs-string">"Enter a positive number: "</span>);
    <span class="hljs-built_in">scanf</span>(<span class="hljs-string">"%d"</span>, &amp;n);

    <span class="hljs-comment">// displays the first two terms which is always 0 and 1</span>
    <span class="hljs-built_in">printf</span>(<span class="hljs-string">"Fibonacci Series: %d, %d, "</span>, t1, t2);
    nextTerm = t1 + t2;

    <span class="hljs-keyword">while</span> (nextTerm &lt;= n) {
        <span class="hljs-built_in">printf</span>(<span class="hljs-string">"%d, "</span>, nextTerm);
        t1 = t2;
        t2 = nextTerm;
        nextTerm = t1 + t2;
    }

    <span class="hljs-keyword">return</span> <span class="hljs-number">0</span>;
}

#include <stdio.h>

int main() {

int t1 = 0, t2 = 1, nextTerm = 0, n;

printf("Enter a positive number: ");

scanf("%d", &n);

// displays the first two terms which is always 0 and 1

printf("Fibonacci Series: %d, %d, ", t1, t2);

nextTerm = t1 + t2;

while (nextTerm <= n) {

printf("%d, ", nextTerm);

t1 = t2;

t2 = nextTerm;

nextTerm = t1 + t2;

}

return 0;

}

Output


<samp>Enter a positive integer: 100
Fibonacci Series: 0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, </samp>

<samp>Enter a positive integer: 100

Fibonacci Series: 0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, </samp>

C Program to GCD Using for loop and if Statement


<span class="hljs-meta">#<span class="hljs-meta-keyword">include</span> <span class="hljs-meta-string">&lt;stdio.h&gt;</span></span>
<span class="hljs-function"><span class="hljs-keyword">int</span> <span class="hljs-title">main</span><span class="hljs-params">()</span>
</span>{
    <span class="hljs-keyword">int</span> n1, n2, i, gcd;

    <span class="hljs-built_in">printf</span>(<span class="hljs-string">"Enter two integers: "</span>);
    <span class="hljs-built_in">scanf</span>(<span class="hljs-string">"%d %d"</span>, &amp;n1, &amp;n2);

    <span class="hljs-keyword">for</span>(i=<span class="hljs-number">1</span>; i &lt;= n1 &amp;&amp; i &lt;= n2; ++i)
    {
        <span class="hljs-comment">// Checks if i is factor of both integers</span>
        <span class="hljs-keyword">if</span>(n1%i==<span class="hljs-number">0</span> &amp;&amp; n2%i==<span class="hljs-number">0</span>)
            gcd = i;
    }

    <span class="hljs-built_in">printf</span>(<span class="hljs-string">"G.C.D of %d and %d is %d"</span>, n1, n2, gcd);

    <span class="hljs-keyword">return</span> <span class="hljs-number">0</span>;
}

#include <stdio.h>

int main()

{

int n1, n2, i, gcd;

printf("Enter two integers: ");

scanf("%d %d", &n1, &n2);

for(i=1; i <= n1 && i <= n2; ++i)

{

// Checks if i is factor of both integers

if(n1%i==0 && n2%i==0)

gcd = i;

}

printf("G.C.D of %d and %d is %d", n1, n2, gcd);

return 0;

}

C Program to GCD Using while loop and if…else Statement


<span class="hljs-meta">#<span class="hljs-meta-keyword">include</span> <span class="hljs-meta-string">&lt;stdio.h&gt;</span></span>
<span class="hljs-function"><span class="hljs-keyword">int</span> <span class="hljs-title">main</span><span class="hljs-params">()</span>
</span>{
    <span class="hljs-keyword">int</span> n1, n2;
    
    <span class="hljs-built_in">printf</span>(<span class="hljs-string">"Enter two positive integers: "</span>);
    <span class="hljs-built_in">scanf</span>(<span class="hljs-string">"%d %d"</span>,&amp;n1,&amp;n2);

    <span class="hljs-keyword">while</span>(n1!=n2)
    {
        <span class="hljs-keyword">if</span>(n1 &gt; n2)
            n1 -= n2;
        <span class="hljs-keyword">else</span>
            n2 -= n1;
    }
    <span class="hljs-built_in">printf</span>(<span class="hljs-string">"GCD = %d"</span>,n1);

    <span class="hljs-keyword">return</span> <span class="hljs-number">0</span>;
}

#include <stdio.h>

int main()

{

int n1, n2;

printf("Enter two positive integers: ");

scanf("%d %d",&n1,&n2);

while(n1!=n2)

{

if(n1 > n2)

n1 -= n2;

else

n2 -= n1;

}

printf("GCD = %d",n1);

return 0;

}

Output


<samp>Enter two positive integers: 81
153
GCD = 9</samp>

<samp>Enter two positive integers: 81

153

GCD = 9</samp>

C Program to GCD for both positive and negative numbers


<span class="hljs-meta">#<span class="hljs-meta-keyword">include</span> <span class="hljs-meta-string">&lt;stdio.h&gt;</span></span>
<span class="hljs-function"><span class="hljs-keyword">int</span> <span class="hljs-title">main</span><span class="hljs-params">()</span>
</span>{
    <span class="hljs-keyword">int</span> n1, n2;

    <span class="hljs-built_in">printf</span>(<span class="hljs-string">"Enter two integers: "</span>);
    <span class="hljs-built_in">scanf</span>(<span class="hljs-string">"%d %d"</span>,&amp;n1,&amp;n2);

    <span class="hljs-comment">// if user enters negative number, sign of the number is changed to positive</span>
    n1 = ( n1 &gt; <span class="hljs-number">0</span>) ? n1 : -n1;
    n2 = ( n2 &gt; <span class="hljs-number">0</span>) ? n2 : -n2;

    <span class="hljs-keyword">while</span>(n1!=n2)
    {
        <span class="hljs-keyword">if</span>(n1 &gt; n2)
            n1 -= n2;
        <span class="hljs-keyword">else</span>
            n2 -= n1;
    }
    <span class="hljs-built_in">printf</span>(<span class="hljs-string">"GCD = %d"</span>,n1);

    <span class="hljs-keyword">return</span> <span class="hljs-number">0</span>;
}

#include <stdio.h>

int main()

{

int n1, n2;

printf("Enter two integers: ");

scanf("%d %d",&n1,&n2);

// if user enters negative number, sign of the number is changed to positive

n1 = ( n1 > 0) ? n1 : -n1;

n2 = ( n2 > 0) ? n2 : -n2;

while(n1!=n2)

{

if(n1 > n2)

n1 -= n2;

else

n2 -= n1;

}

printf("GCD = %d",n1);

return 0;

}

Output


<samp>Enter two integers: 81
-153
GCD = 9</samp>

<samp>Enter two integers: 81

-153

GCD = 9</samp>

C Program to LCM using while and if


<span class="hljs-meta">#<span class="hljs-meta-keyword">include</span> <span class="hljs-meta-string">&lt;stdio.h&gt;</span></span>
<span class="hljs-function"><span class="hljs-keyword">int</span> <span class="hljs-title">main</span><span class="hljs-params">()</span> </span>{
    <span class="hljs-keyword">int</span> n1, n2, max;
    <span class="hljs-built_in">printf</span>(<span class="hljs-string">"Enter two positive integers: "</span>);
    <span class="hljs-built_in">scanf</span>(<span class="hljs-string">"%d %d"</span>, &amp;n1, &amp;n2);

    <span class="hljs-comment">// maximum number between n1 and n2 is stored in min</span>
    max = (n1 &gt; n2) ? n1 : n2;

    <span class="hljs-keyword">while</span> (<span class="hljs-number">1</span>) {
        <span class="hljs-keyword">if</span> (max % n1 == <span class="hljs-number">0</span> &amp;&amp; max % n2 == <span class="hljs-number">0</span>) {
            <span class="hljs-built_in">printf</span>(<span class="hljs-string">"The LCM of %d and %d is %d."</span>, n1, n2, max);
            <span class="hljs-keyword">break</span>;
        }
        ++max;
    }
    <span class="hljs-keyword">return</span> <span class="hljs-number">0</span>;
}

#include <stdio.h>

int main() {

int n1, n2, max;

printf("Enter two positive integers: ");

scanf("%d %d", &n1, &n2);

// maximum number between n1 and n2 is stored in min

max = (n1 > n2) ? n1 : n2;

while (1) {

if (max % n1 == 0 && max % n2 == 0) {

printf("The LCM of %d and %d is %d.", n1, n2, max);

break;

}

++max;

}

return 0;

}

Output


<samp>Enter two positive integers: 72
120
The LCM of 72 and 120 is 360.</samp>

<samp>Enter two positive integers: 72

120

The LCM of 72 and 120 is 360.</samp>

C Program to LCM Calculation Using GCD


<span class="hljs-meta">#<span class="hljs-meta-keyword">include</span> <span class="hljs-meta-string">&lt;stdio.h&gt;</span></span>
<span class="hljs-function"><span class="hljs-keyword">int</span> <span class="hljs-title">main</span><span class="hljs-params">()</span> </span>{
    <span class="hljs-keyword">int</span> n1, n2, i, gcd, lcm;
    <span class="hljs-built_in">printf</span>(<span class="hljs-string">"Enter two positive integers: "</span>);
    <span class="hljs-built_in">scanf</span>(<span class="hljs-string">"%d %d"</span>, &amp;n1, &amp;n2);

    <span class="hljs-keyword">for</span> (i = <span class="hljs-number">1</span>; i &lt;= n1 &amp;&amp; i &lt;= n2; ++i) {
        
        <span class="hljs-comment">// check if i is a factor of both integers</span>
        <span class="hljs-keyword">if</span> (n1 % i == <span class="hljs-number">0</span> &amp;&amp; n2 % i == <span class="hljs-number">0</span>)
            gcd = i;
    }

    lcm = (n1 * n2) / gcd;

    <span class="hljs-built_in">printf</span>(<span class="hljs-string">"The LCM of two numbers %d and %d is %d."</span>, n1, n2, lcm);
    <span class="hljs-keyword">return</span> <span class="hljs-number">0</span>;
}

#include <stdio.h>

int main() {

int n1, n2, i, gcd, lcm;

printf("Enter two positive integers: ");

scanf("%d %d", &n1, &n2);

for (i = 1; i <= n1 && i <= n2; ++i) {

// check if i is a factor of both integers

if (n1 % i == 0 && n2 % i == 0)

gcd = i;

}

lcm = (n1 * n2) / gcd;

printf("The LCM of two numbers %d and %d is %d.", n1, n2, lcm);

return 0;

}

Output


<samp>Enter two positive integers: 72
120
The LCM of two numbers 72 and 120 is 360.</samp>

<samp>Enter two positive integers: 72

120

The LCM of two numbers 72 and 120 is 360.</samp>

Program to Print English Alphabets


<span class="hljs-meta">#<span class="hljs-meta-keyword">include</span> <span class="hljs-meta-string">&lt;stdio.h&gt;</span></span>
<span class="hljs-function"><span class="hljs-keyword">int</span> <span class="hljs-title">main</span><span class="hljs-params">()</span> </span>{
    <span class="hljs-keyword">char</span> c;
    <span class="hljs-keyword">for</span> (c = <span class="hljs-string">'A'</span>; c &lt;= <span class="hljs-string">'Z'</span>; ++c)
        <span class="hljs-built_in">printf</span>(<span class="hljs-string">"%c "</span>, c);
    <span class="hljs-keyword">return</span> <span class="hljs-number">0</span>;
}

#include <stdio.h>

int main() {

char c;

for (c = 'A'; c <= 'Z'; ++c)

printf("%c ", c);

return 0;

}

Output


<samp>A B C D E F G H I J K L M N O P Q R S T U V W X Y Z</samp>

C Program to Print Lowercase/Uppercase alphabets


<span class="hljs-meta">#<span class="hljs-meta-keyword">include</span> <span class="hljs-meta-string">&lt;stdio.h&gt;</span></span>
<span class="hljs-function"><span class="hljs-keyword">int</span> <span class="hljs-title">main</span><span class="hljs-params">()</span> </span>{
    <span class="hljs-keyword">char</span> c;
    <span class="hljs-built_in">printf</span>(<span class="hljs-string">"Enter u to display uppercase alphabets.\n"</span>);
    <span class="hljs-built_in">printf</span>(<span class="hljs-string">"Enter l to display lowercase alphabets. \n"</span>);
    <span class="hljs-built_in">scanf</span>(<span class="hljs-string">"%c"</span>, &amp;c);

    <span class="hljs-keyword">if</span> (c == <span class="hljs-string">'U'</span> || c == <span class="hljs-string">'u'</span>) {
        <span class="hljs-keyword">for</span> (c = <span class="hljs-string">'A'</span>; c &lt;= <span class="hljs-string">'Z'</span>; ++c)
            <span class="hljs-built_in">printf</span>(<span class="hljs-string">"%c "</span>, c);
    } <span class="hljs-keyword">else</span> <span class="hljs-keyword">if</span> (c == <span class="hljs-string">'L'</span> || c == <span class="hljs-string">'l'</span>) {
        <span class="hljs-keyword">for</span> (c = <span class="hljs-string">'a'</span>; c &lt;= <span class="hljs-string">'z'</span>; ++c)
            <span class="hljs-built_in">printf</span>(<span class="hljs-string">"%c "</span>, c);
    } <span class="hljs-keyword">else</span> {
        <span class="hljs-built_in">printf</span>(<span class="hljs-string">"Error! You entered an invalid character."</span>);
    }

    <span class="hljs-keyword">return</span> <span class="hljs-number">0</span>;
}

#include <stdio.h>

int main() {

char c;

printf("Enter u to display uppercase alphabets.\n");

printf("Enter l to display lowercase alphabets. \n");

scanf("%c", &c);

if (c == 'U' || c == 'u') {

for (c = 'A'; c <= 'Z'; ++c)

printf("%c ", c);

} else if (c == 'L' || c == 'l') {

for (c = 'a'; c <= 'z'; ++c)

printf("%c ", c);

} else {

printf("Error! You entered an invalid character.");

}

return 0;

}

Output


<samp>Enter u to display uppercase alphabets. 
Enter l to display lowercase alphabets. l
a b c d e f g h i j k l m n o p q r s t u v w x y z</samp>

<samp>Enter u to display uppercase alphabets.

Enter l to display lowercase alphabets. l

a b c d e f g h i j k l m n o p q r s t u v w x y z</samp>

C Program to Count the Number of Digits


<span class="hljs-meta">#<span class="hljs-meta-keyword">include</span> <span class="hljs-meta-string">&lt;stdio.h&gt;</span></span>
<span class="hljs-function"><span class="hljs-keyword">int</span> <span class="hljs-title">main</span><span class="hljs-params">()</span> </span>{
    <span class="hljs-keyword">long</span> <span class="hljs-keyword">long</span> n;
    <span class="hljs-keyword">int</span> count = <span class="hljs-number">0</span>;
    <span class="hljs-built_in">printf</span>(<span class="hljs-string">"Enter an integer: "</span>);
    <span class="hljs-built_in">scanf</span>(<span class="hljs-string">"%lld"</span>, &amp;n);
 
    <span class="hljs-comment">// iterate until n becomes 0</span>
    <span class="hljs-comment">// remove last digit from n in each iteration</span>
    <span class="hljs-comment">// increase count by 1 in each iteration</span>
    <span class="hljs-keyword">while</span> (n != <span class="hljs-number">0</span>) {
        n /= <span class="hljs-number">10</span>;     <span class="hljs-comment">// n = n/10</span>
        ++count;
    }

    <span class="hljs-built_in">printf</span>(<span class="hljs-string">"Number of digits: %d"</span>, count);
}

#include <stdio.h>

int main() {

long long n;

int count = 0;

printf("Enter an integer: ");

scanf("%lld", &n);

// iterate until n becomes 0

// remove last digit from n in each iteration

// increase count by 1 in each iteration

while (n != 0) {

n /= 10; // n = n/10

++count;

}

printf("Number of digits: %d", count);

}

Output


<samp>Enter an integer: 3452
Number of digits: 4</samp>

<samp>Enter an integer: 3452

Number of digits: 4</samp>

C Program to Reverse an Integer


<span class="hljs-meta">#<span class="hljs-meta-keyword">include</span> <span class="hljs-meta-string">&lt;stdio.h&gt;</span></span>
<span class="hljs-function"><span class="hljs-keyword">int</span> <span class="hljs-title">main</span><span class="hljs-params">()</span> </span>{
    <span class="hljs-keyword">int</span> n, rev = <span class="hljs-number">0</span>, remainder;
    <span class="hljs-built_in">printf</span>(<span class="hljs-string">"Enter an integer: "</span>);
    <span class="hljs-built_in">scanf</span>(<span class="hljs-string">"%d"</span>, &amp;n);
    <span class="hljs-keyword">while</span> (n != <span class="hljs-number">0</span>) {
        remainder = n % <span class="hljs-number">10</span>;
        rev = rev * <span class="hljs-number">10</span> + remainder;
        n /= <span class="hljs-number">10</span>;
    }
    <span class="hljs-built_in">printf</span>(<span class="hljs-string">"Reversed number = %d"</span>, rev);
    <span class="hljs-keyword">return</span> <span class="hljs-number">0</span>;
}

#include <stdio.h>

int main() {

int n, rev = 0, remainder;

printf("Enter an integer: ");

scanf("%d", &n);

while (n != 0) {

remainder = n % 10;

rev = rev * 10 + remainder;

n /= 10;

}

printf("Reversed number = %d", rev);

return 0;

}

Output


<samp>Enter an integer: 2345
Reversed number = 5432</samp>

<samp>Enter an integer: 2345

Reversed number = 5432</samp>

C Program to Power of a Number Using the while Loop


<span class="hljs-meta">#<span class="hljs-meta-keyword">include</span> <span class="hljs-meta-string">&lt;stdio.h&gt;</span></span>
<span class="hljs-function"><span class="hljs-keyword">int</span> <span class="hljs-title">main</span><span class="hljs-params">()</span> </span>{
    <span class="hljs-keyword">int</span> base, <span class="hljs-built_in">exp</span>;
    <span class="hljs-keyword">long</span> <span class="hljs-keyword">long</span> result = <span class="hljs-number">1</span>;
    <span class="hljs-built_in">printf</span>(<span class="hljs-string">"Enter a base number: "</span>);
    <span class="hljs-built_in">scanf</span>(<span class="hljs-string">"%d"</span>, &amp;base);
    <span class="hljs-built_in">printf</span>(<span class="hljs-string">"Enter an exponent: "</span>);
    <span class="hljs-built_in">scanf</span>(<span class="hljs-string">"%d"</span>, &amp;<span class="hljs-built_in">exp</span>);

    <span class="hljs-keyword">while</span> (<span class="hljs-built_in">exp</span> != <span class="hljs-number">0</span>) {
        result *= base;
        --<span class="hljs-built_in">exp</span>;
    }
    <span class="hljs-built_in">printf</span>(<span class="hljs-string">"Answer = %lld"</span>, result);
    <span class="hljs-keyword">return</span> <span class="hljs-number">0</span>;
}

#include <stdio.h>

int main() {

int base, exp;

long long result = 1;

printf("Enter a base number: ");

scanf("%d", &base);

printf("Enter an exponent: ");

scanf("%d", &exp);

while (exp != 0) {

result *= base;

--exp;

}

printf("Answer = %lld", result);

return 0;

}

Output


<samp>Enter a base number: 3
Enter an exponent: 4
Answer = 81</samp>

<samp>Enter a base number: 3

Enter an exponent: 4

Answer = 81</samp>

C Program to Power Using pow() Function


<span class="hljs-meta">#<span class="hljs-meta-keyword">include</span> <span class="hljs-meta-string">&lt;math.h&gt;</span></span>
<span class="hljs-meta">#<span class="hljs-meta-keyword">include</span> <span class="hljs-meta-string">&lt;stdio.h&gt;</span></span>

<span class="hljs-function"><span class="hljs-keyword">int</span> <span class="hljs-title">main</span><span class="hljs-params">()</span> </span>{
    <span class="hljs-keyword">double</span> base, <span class="hljs-built_in">exp</span>, result;
    <span class="hljs-built_in">printf</span>(<span class="hljs-string">"Enter a base number: "</span>);
    <span class="hljs-built_in">scanf</span>(<span class="hljs-string">"%lf"</span>, &amp;base);
    <span class="hljs-built_in">printf</span>(<span class="hljs-string">"Enter an exponent: "</span>);
    <span class="hljs-built_in">scanf</span>(<span class="hljs-string">"%lf"</span>, &amp;<span class="hljs-built_in">exp</span>);

    <span class="hljs-comment">// calculates the power</span>
    result = <span class="hljs-built_in">pow</span>(base, <span class="hljs-built_in">exp</span>);

    <span class="hljs-built_in">printf</span>(<span class="hljs-string">"%.1lf^%.1lf = %.2lf"</span>, base, <span class="hljs-built_in">exp</span>, result);
    <span class="hljs-keyword">return</span> <span class="hljs-number">0</span>;
}

#include <math.h>

#include <stdio.h>

int main() {

double base, exp, result;

printf("Enter a base number: ");

scanf("%lf", &base);

printf("Enter an exponent: ");

scanf("%lf", &exp);

// calculates the power

result = pow(base, exp);

printf("%.1lf^%.1lf = %.2lf", base, exp, result);

return 0;

}

Output


<samp>Enter a base number: 2.3
Enter an exponent: 4.5
2.3^4.5 = 42.44</samp>

<samp>Enter a base number: 2.3

Enter an exponent: 4.5

2.3^4.5 = 42.44</samp>

C Program to Check Palindrome


<span class="hljs-meta">#<span class="hljs-meta-keyword">include</span> <span class="hljs-meta-string">&lt;stdio.h&gt;</span></span>
<span class="hljs-function"><span class="hljs-keyword">int</span> <span class="hljs-title">main</span><span class="hljs-params">()</span> </span>{
    <span class="hljs-keyword">int</span> n, reversedN = <span class="hljs-number">0</span>, remainder, originalN;
    <span class="hljs-built_in">printf</span>(<span class="hljs-string">"Enter an integer: "</span>);
    <span class="hljs-built_in">scanf</span>(<span class="hljs-string">"%d"</span>, &amp;n);
    originalN = n;

    <span class="hljs-comment">// reversed integer is stored in reversedN</span>
    <span class="hljs-keyword">while</span> (n != <span class="hljs-number">0</span>) {
        remainder = n % <span class="hljs-number">10</span>;
        reversedN = reversedN * <span class="hljs-number">10</span> + remainder;
        n /= <span class="hljs-number">10</span>;
    }

    <span class="hljs-comment">// palindrome if orignalN and reversedN are equal</span>
    <span class="hljs-keyword">if</span> (originalN == reversedN)
        <span class="hljs-built_in">printf</span>(<span class="hljs-string">"%d is a palindrome."</span>, originalN);
    <span class="hljs-keyword">else</span>
        <span class="hljs-built_in">printf</span>(<span class="hljs-string">"%d is not a palindrome."</span>, originalN);

    <span class="hljs-keyword">return</span> <span class="hljs-number">0</span>;
}

#include <stdio.h>

int main() {

int n, reversedN = 0, remainder, originalN;

printf("Enter an integer: ");

scanf("%d", &n);

originalN = n;

// reversed integer is stored in reversedN

while (n != 0) {

remainder = n % 10;

reversedN = reversedN * 10 + remainder;

n /= 10;

}

// palindrome if orignalN and reversedN are equal

if (originalN == reversedN)

printf("%d is a palindrome.", originalN);

else

printf("%d is not a palindrome.", originalN);

return 0;

}

Output


<samp>Enter an integer: 1001
1001 is a palindrome.</samp>

<samp>Enter an integer: 1001

1001 is a palindrome.</samp>

C Program to Check Prime Number


<span class="hljs-meta">#<span class="hljs-meta-keyword">include</span> <span class="hljs-meta-string">&lt;stdio.h&gt;</span></span>
<span class="hljs-function"><span class="hljs-keyword">int</span> <span class="hljs-title">main</span><span class="hljs-params">()</span> </span>{
    <span class="hljs-keyword">int</span> n, i, flag = <span class="hljs-number">0</span>;
    <span class="hljs-built_in">printf</span>(<span class="hljs-string">"Enter a positive integer: "</span>);
    <span class="hljs-built_in">scanf</span>(<span class="hljs-string">"%d"</span>, &amp;n);

    <span class="hljs-keyword">for</span> (i = <span class="hljs-number">2</span>; i &lt;= n / <span class="hljs-number">2</span>; ++i) {

        <span class="hljs-comment">// condition for non-prime</span>
        <span class="hljs-keyword">if</span> (n % i == <span class="hljs-number">0</span>) {
            flag = <span class="hljs-number">1</span>;
            <span class="hljs-keyword">break</span>;
        }
    }

    <span class="hljs-keyword">if</span> (n == <span class="hljs-number">1</span>) {
        <span class="hljs-built_in">printf</span>(<span class="hljs-string">"1 is neither prime nor composite."</span>);
    }
    <span class="hljs-keyword">else</span> {
        <span class="hljs-keyword">if</span> (flag == <span class="hljs-number">0</span>)
            <span class="hljs-built_in">printf</span>(<span class="hljs-string">"%d is a prime number."</span>, n);
        <span class="hljs-keyword">else</span>
            <span class="hljs-built_in">printf</span>(<span class="hljs-string">"%d is not a prime number."</span>, n);
    }

    <span class="hljs-keyword">return</span> <span class="hljs-number">0</span>;
}

#include <stdio.h>

int main() {

int n, i, flag = 0;

printf("Enter a positive integer: ");

scanf("%d", &n);

for (i = 2; i <= n / 2; ++i) {

// condition for non-prime

if (n % i == 0) {

flag = 1;

break;

}

if (n == 1) {

printf("1 is neither prime nor composite.");

}

else {

if (flag == 0)

printf("%d is a prime number.", n);

else

printf("%d is not a prime number.", n);

}

return 0;

}

Output


<samp>Enter a positive integer: 29
29 is a prime number.</samp>

<samp>Enter a positive integer: 29

29 is a prime number.</samp>

C Program to Display Prime Numbers Between Two Intervals


<span class="hljs-meta">#<span class="hljs-meta-keyword">include</span> <span class="hljs-meta-string">&lt;stdio.h&gt;</span></span>

<span class="hljs-function"><span class="hljs-keyword">int</span> <span class="hljs-title">main</span><span class="hljs-params">()</span> </span>{
   <span class="hljs-keyword">int</span> low, high, i, flag;
   <span class="hljs-built_in">printf</span>(<span class="hljs-string">"Enter two numbers(intervals): "</span>);
   <span class="hljs-built_in">scanf</span>(<span class="hljs-string">"%d %d"</span>, &amp;low, &amp;high);
   <span class="hljs-built_in">printf</span>(<span class="hljs-string">"Prime numbers between %d and %d are: "</span>, low, high);

   <span class="hljs-comment">// iteration until low is not equal to high</span>
   <span class="hljs-keyword">while</span> (low &lt; high) {
      flag = <span class="hljs-number">0</span>;

      <span class="hljs-comment">// ignore numbers less than 2</span>
      <span class="hljs-keyword">if</span> (low &lt;= <span class="hljs-number">1</span>) {
         ++low;
         <span class="hljs-keyword">continue</span>;
      }

      <span class="hljs-comment">// if low is a non-prime number, flag will be 1</span>
      <span class="hljs-keyword">for</span> (i = <span class="hljs-number">2</span>; i &lt;= low / <span class="hljs-number">2</span>; ++i) {

         <span class="hljs-keyword">if</span> (low % i == <span class="hljs-number">0</span>) {
            flag = <span class="hljs-number">1</span>;
            <span class="hljs-keyword">break</span>;
         }
      }

      <span class="hljs-keyword">if</span> (flag == <span class="hljs-number">0</span>)
         <span class="hljs-built_in">printf</span>(<span class="hljs-string">"%d "</span>, low);

      <span class="hljs-comment">// to check prime for the next number</span>
      <span class="hljs-comment">// increase low by 1</span>
      ++low;
   }

   <span class="hljs-keyword">return</span> <span class="hljs-number">0</span>;
}

#include <stdio.h>

int main() {

int low, high, i, flag;

printf("Enter two numbers(intervals): ");

scanf("%d %d", &low, &high);

printf("Prime numbers between %d and %d are: ", low, high);

// iteration until low is not equal to high

while (low < high) {

flag = 0;

// ignore numbers less than 2

if (low <= 1) {

++low;

continue;

}

// if low is a non-prime number, flag will be 1

for (i = 2; i <= low / 2; ++i) {

if (low % i == 0) {

flag = 1;

break;

}

if (flag == 0)

printf("%d ", low);

// to check prime for the next number

// increase low by 1

++low;

}

return 0;

}

Output


<samp>Enter two numbers(intervals): 20 
50
Prime numbers between 20 and 50 are: 23 29 31 37 41 43 47</samp>

<samp>Enter two numbers(intervals): 20

Prime numbers between 20 and 50 are: 23 29 31 37 41 43 47</samp>

C Program to Display Prime Numbers when Larger Number is Entered first


<span class="hljs-meta">#<span class="hljs-meta-keyword">include</span> <span class="hljs-meta-string">&lt;stdio.h&gt;</span></span>

<span class="hljs-function"><span class="hljs-keyword">int</span> <span class="hljs-title">main</span><span class="hljs-params">()</span> </span>{
   <span class="hljs-keyword">int</span> low, high, i, flag, temp;
   <span class="hljs-built_in">printf</span>(<span class="hljs-string">"Enter two numbers(intervals): "</span>);
   <span class="hljs-built_in">scanf</span>(<span class="hljs-string">"%d %d"</span>, &amp;low, &amp;high);

   <span class="hljs-comment">// swap numbers if low is greather than high</span>
   <span class="hljs-keyword">if</span> (low &gt; high) {
      temp = low;
      low = high;
      high = temp;
   }

   <span class="hljs-built_in">printf</span>(<span class="hljs-string">"Prime numbers between %d and %d are: "</span>, low, high);
   <span class="hljs-keyword">while</span> (low &lt; high) {
      flag = <span class="hljs-number">0</span>;

      <span class="hljs-comment">// ignore numbers less than 2</span>
      <span class="hljs-keyword">if</span> (low &lt;= <span class="hljs-number">1</span>) {
         ++low;
         <span class="hljs-keyword">continue</span>;
      }

      <span class="hljs-keyword">for</span> (i = <span class="hljs-number">2</span>; i &lt;= low / <span class="hljs-number">2</span>; ++i) {
         <span class="hljs-keyword">if</span> (low % i == <span class="hljs-number">0</span>) {
            flag = <span class="hljs-number">1</span>;
            <span class="hljs-keyword">break</span>;
         }
      }
      <span class="hljs-keyword">if</span> (flag == <span class="hljs-number">0</span>)
         <span class="hljs-built_in">printf</span>(<span class="hljs-string">"%d "</span>, low);
      ++low;
   }

   <span class="hljs-keyword">return</span> <span class="hljs-number">0</span>;
}

#include <stdio.h>

int main() {

int low, high, i, flag, temp;

printf("Enter two numbers(intervals): ");

scanf("%d %d", &low, &high);

// swap numbers if low is greather than high

if (low > high) {

temp = low;

low = high;

high = temp;

}

printf("Prime numbers between %d and %d are: ", low, high);

while (low < high) {

flag = 0;

// ignore numbers less than 2

if (low <= 1) {

++low;

continue;

}

for (i = 2; i <= low / 2; ++i) {

if (low % i == 0) {

flag = 1;

break;

}

if (flag == 0)

printf("%d ", low);

++low;

}

return 0;

}


<span class="hljs-meta">#<span class="hljs-meta-keyword">include</span> <span class="hljs-meta-string">&lt;stdio.h&gt;</span></span>
<span class="hljs-function"><span class="hljs-keyword">int</span> <span class="hljs-title">main</span><span class="hljs-params">()</span> </span>{
    <span class="hljs-keyword">int</span> num, originalNum, remainder, result = <span class="hljs-number">0</span>;
    <span class="hljs-built_in">printf</span>(<span class="hljs-string">"Enter a three-digit integer: "</span>);
    <span class="hljs-built_in">scanf</span>(<span class="hljs-string">"%d"</span>, &amp;num);
    originalNum = num;

    <span class="hljs-keyword">while</span> (originalNum != <span class="hljs-number">0</span>) {
       <span class="hljs-comment">// remainder contains the last digit</span>
        remainder = originalNum % <span class="hljs-number">10</span>;
        
       result += remainder * remainder * remainder;
        
       <span class="hljs-comment">// removing last digit from the orignal number</span>
       originalNum /= <span class="hljs-number">10</span>;
    }

    <span class="hljs-keyword">if</span> (result == num)
        <span class="hljs-built_in">printf</span>(<span class="hljs-string">"%d is an Armstrong number."</span>, num);
    <span class="hljs-keyword">else</span>
        <span class="hljs-built_in">printf</span>(<span class="hljs-string">"%d is not an Armstrong number."</span>, num);

    <span class="hljs-keyword">return</span> <span class="hljs-number">0</span>;
}

#include <stdio.h>

int main() {

int num, originalNum, remainder, result = 0;

printf("Enter a three-digit integer: ");

scanf("%d", &num);

originalNum = num;

while (originalNum != 0) {

// remainder contains the last digit

remainder = originalNum % 10;

result += remainder * remainder * remainder;

// removing last digit from the orignal number

originalNum /= 10;

}

if (result == num)

printf("%d is an Armstrong number.", num);

else

printf("%d is not an Armstrong number.", num);

return 0;

}

Output


<samp>Enter a three-digit integer: 371
371 is an Armstrong number.</samp>

<samp>Enter a three-digit integer: 371

371 is an Armstrong number.</samp>

C Program to Check Armstrong Number of n digits


<span class="hljs-meta">#<span class="hljs-meta-keyword">include</span> <span class="hljs-meta-string">&lt;math.h&gt;</span></span>
<span class="hljs-meta">#<span class="hljs-meta-keyword">include</span> <span class="hljs-meta-string">&lt;stdio.h&gt;</span></span>

<span class="hljs-function"><span class="hljs-keyword">int</span> <span class="hljs-title">main</span><span class="hljs-params">()</span> </span>{
   <span class="hljs-keyword">int</span> num, originalNum, remainder, n = <span class="hljs-number">0</span>;
   <span class="hljs-keyword">float</span> result = <span class="hljs-number">0.0</span>;

   <span class="hljs-built_in">printf</span>(<span class="hljs-string">"Enter an integer: "</span>);
   <span class="hljs-built_in">scanf</span>(<span class="hljs-string">"%d"</span>, &amp;num);

   originalNum = num;

   <span class="hljs-comment">// store the number of digits of num in n</span>
   <span class="hljs-keyword">for</span> (originalNum = num; originalNum != <span class="hljs-number">0</span>; ++n) {
       originalNum /= <span class="hljs-number">10</span>;
   }

   <span class="hljs-keyword">for</span> (originalNum = num; originalNum != <span class="hljs-number">0</span>; originalNum /= <span class="hljs-number">10</span>) {
       remainder = originalNum % <span class="hljs-number">10</span>;

      <span class="hljs-comment">// store the sum of the power of individual digits in result</span>
      result += <span class="hljs-built_in">pow</span>(remainder, n);
   }

   <span class="hljs-comment">// if num is equal to result, the number is an Armstrong number</span>
   <span class="hljs-keyword">if</span> ((<span class="hljs-keyword">int</span>)result == num)
    <span class="hljs-built_in">printf</span>(<span class="hljs-string">"%d is an Armstrong number."</span>, num);
   <span class="hljs-keyword">else</span>
    <span class="hljs-built_in">printf</span>(<span class="hljs-string">"%d is not an Armstrong number."</span>, num);
   <span class="hljs-keyword">return</span> <span class="hljs-number">0</span>;
}

#include <math.h>

#include <stdio.h>

int main() {

int num, originalNum, remainder, n = 0;

float result = 0.0;

printf("Enter an integer: ");

scanf("%d", &num);

originalNum = num;

// store the number of digits of num in n

for (originalNum = num; originalNum != 0; ++n) {

originalNum /= 10;

}

for (originalNum = num; originalNum != 0; originalNum /= 10) {

remainder = originalNum % 10;

// store the sum of the power of individual digits in result

result += pow(remainder, n);

}

// if num is equal to result, the number is an Armstrong number

if ((int)result == num)

printf("%d is an Armstrong number.", num);

else

printf("%d is not an Armstrong number.", num);

return 0;

}

Output


<samp>Enter an integer: 1634
1634 is an Armstrong number.</samp>

<samp>Enter an integer: 1634

1634 is an Armstrong number.</samp>

C Program to Display Armstrong Numbers Between Two Integers


<span class="hljs-meta">#<span class="hljs-meta-keyword">include</span> <span class="hljs-meta-string">&lt;math.h&gt;</span></span>
<span class="hljs-meta">#<span class="hljs-meta-keyword">include</span> <span class="hljs-meta-string">&lt;stdio.h&gt;</span></span>
<span class="hljs-function"><span class="hljs-keyword">int</span> <span class="hljs-title">main</span><span class="hljs-params">()</span> </span>{
   <span class="hljs-keyword">int</span> low, high, number, originalNumber, rem, count = <span class="hljs-number">0</span>;
   <span class="hljs-keyword">double</span> result = <span class="hljs-number">0.0</span>;
   <span class="hljs-built_in">printf</span>(<span class="hljs-string">"Enter two numbers(intervals): "</span>);
   <span class="hljs-built_in">scanf</span>(<span class="hljs-string">"%d %d"</span>, &amp;low, &amp;high);
   <span class="hljs-built_in">printf</span>(<span class="hljs-string">"Armstrong numbers between %d and %d are: "</span>, low, high);

   <span class="hljs-comment">// iterate number from (low + 1) to (high - 1)</span>
   <span class="hljs-comment">// In each iteration, check if number is Armstrong</span>
   <span class="hljs-keyword">for</span> (number = low + <span class="hljs-number">1</span>; number &lt; high; ++number) {
      originalNumber = number;

      <span class="hljs-comment">// number of digits calculation</span>
      <span class="hljs-keyword">while</span> (originalNumber != <span class="hljs-number">0</span>) {
         originalNumber /= <span class="hljs-number">10</span>;
         ++count;
      }

      originalNumber = number;

      <span class="hljs-comment">// result contains sum of nth power of individual digits</span>
      <span class="hljs-keyword">while</span> (originalNumber != <span class="hljs-number">0</span>) {
         rem = originalNumber % <span class="hljs-number">10</span>;
         result += <span class="hljs-built_in">pow</span>(rem, count);
         originalNumber /= <span class="hljs-number">10</span>;
      }

      <span class="hljs-comment">// check if number is equal to the sum of nth power of individual digits</span>
      <span class="hljs-keyword">if</span> ((<span class="hljs-keyword">int</span>)result == number) {
         <span class="hljs-built_in">printf</span>(<span class="hljs-string">"%d "</span>, number);
      }

      <span class="hljs-comment">// resetting the values</span>
      count = <span class="hljs-number">0</span>;
      result = <span class="hljs-number">0</span>;
   }

   <span class="hljs-keyword">return</span> <span class="hljs-number">0</span>;
}

#include <math.h>

#include <stdio.h>

int main() {

int low, high, number, originalNumber, rem, count = 0;

double result = 0.0;

printf("Enter two numbers(intervals): ");

scanf("%d %d", &low, &high);

printf("Armstrong numbers between %d and %d are: ", low, high);

// iterate number from (low + 1) to (high - 1)

// In each iteration, check if number is Armstrong

for (number = low + 1; number < high; ++number) {

originalNumber = number;

// number of digits calculation

while (originalNumber != 0) {

originalNumber /= 10;

++count;

}

originalNumber = number;

// result contains sum of nth power of individual digits

while (originalNumber != 0) {

rem = originalNumber % 10;

result += pow(rem, count);

originalNumber /= 10;

}

// check if number is equal to the sum of nth power of individual digits

if ((int)result == number) {

printf("%d ", number);

}

// resetting the values

count = 0;

result = 0;

}

return 0;

}

Output


<samp>Enter two numbers(intervals): 200
2000
Armstrong numbers between 200 and 2000 are: 370 371 407 1634 </samp>

<samp>Enter two numbers(intervals): 200

2000

Armstrong numbers between 200 and 2000 are: 370 371 407 1634 </samp>

C Program to Find Factors of a Positive Integer


<span class="hljs-meta">#<span class="hljs-meta-keyword">include</span> <span class="hljs-meta-string">&lt;stdio.h&gt;</span></span>
<span class="hljs-function"><span class="hljs-keyword">int</span> <span class="hljs-title">main</span><span class="hljs-params">()</span> </span>{
    <span class="hljs-keyword">int</span> num, i;
    <span class="hljs-built_in">printf</span>(<span class="hljs-string">"Enter a positive integer: "</span>);
    <span class="hljs-built_in">scanf</span>(<span class="hljs-string">"%d"</span>, &amp;num);
    <span class="hljs-built_in">printf</span>(<span class="hljs-string">"Factors of %d are: "</span>, num);
    <span class="hljs-keyword">for</span> (i = <span class="hljs-number">1</span>; i &lt;= num; ++i) {
        <span class="hljs-keyword">if</span> (num % i == <span class="hljs-number">0</span>) {
            <span class="hljs-built_in">printf</span>(<span class="hljs-string">"%d "</span>, i);
        }
    }
    <span class="hljs-keyword">return</spa