01: #include <stdio.h>
02:
03: int is_prime(int x);
04:
05: int main(void)
06: {
07: int x;
08:
09: printf("Input a number:");
10: scanf("%d", &x);
11: if(is_prime(x) == 1) printf("%d is a prime number.", x);
12: else printf("%d is not a prime number.", x);
13:
14: return 0;
15: }
16:
17: int is_prime(int x)
18: {
19: int i;
20: for(i = x - 1; i > 1;i--)
21: {
22: if(x % i == 0) return 0;
23: }
24: return 1;
25: }