C Program To Check Given Number is Prime or Not

#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:

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

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