program in c
int main() {
int n, i, flag = 0; printf("Enter a positive integer: "); scanf("%d", &n);
// 0 and 1 are not prime numbers // change flag to 1 for non-prime number if (n == 0 || n == 1) flag = 1;
for (i = 2; i <= n / 2; ++i) {
// if n is divisible by i, then n is not prime
// change flag to 1 for non-prime number
if (n % i == 0) {
flag = 1;
break;
}
}
// flag is 0 for prime numbers if (flag == 0) printf("%d is a prime number.", n); else printf("%d is not a prime number.", n);
return 0; }