C：教材例题p21-2.5

GitHenry

#include<stdio.h>
int main()
{
    int a;
    printf("input a munber to check prime:\n");
    scanf("%d", &a);
    for (int i = 2; i < a; i++)
    {
        if(a%i==0){
            printf("%d is not a prime.",a);
            return 0;
        }
    }
    printf("%d is a prime.",a);
    return 0;
}