Home > C Program to find a Prime Number

Below is the program to find whether a given number is a prime number or not. Use this code to find the prime numbers from the given set of integers.

#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 number
        if(n%i == 0)
        {
            flag = 1;
            break;
        }
    }

    if (n == 1) 
    {
      printf("1 is neither a prime nor a composite number.");
    }
    else 
    {
        if (flag == 0)
          printf("%d is a prime number.", n);
        else
          printf("%d is not a prime number.", n);
    }
    
    return 0;
}

Output: 

Enter a positive integer: 29
29 is a prime number.

 

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