In this Example, we’ll learn How to print all prime numbers between two numbers (entered by the user) by making a user-defined function.
C++ Code:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 | #include <stdio.h> #include <iostream> using namespace std; int checkPrimeNumber(int n); int main() { int n1, n2, i, flag; cout<<"Number 1: "; cin>>n1; cout<<"Number 2: "; cin>>n2; cout<<"Prime numbers between "<<n1<<" and "<<n2<<" are: "; for(i=n1+1; i<n2; ++i) { // i is a prime number, flag will be equal to 1 flag = checkPrimeNumber(i); if(flag == 1) cout<<i<<" "; } return 0; } // user-defined function to check prime number int checkPrimeNumber(int n) { int j, flag = 1; for(j=2; j <= n/2; ++j) { if (n%j == 0) { flag =0; break; } } return flag; } |
Output:
If the user enters larger number first, this program will not work as intended. To solve this issue, you need to swap numbers first.
