C语言求素数代码为啥什么也打印不出来

Question

int num, i; 
int    flag = 1;
for ( num = 100; num <= 200; num++){
    //printf ("%d\n",num);
    for ( i = 2; i < num/2; i++){
        if (num % i == 0){
            flag = 0;
            break;
        }
    }
    if (flag){
        printf ("%d ",num);}

}

Answer 1

每次循环之前flag应该设为1，否则第一次不是素数后flag一直是0，后面的就不会输出了

#include <stdio.h>
#include <math.h>
int main()
{
    int num, i;
    int  flag = 1;
    for ( num = 100; num <= 200; num++)
    {
        flag=1;
        for ( i = 2; i <num/2; i++)
        {
            if (num%i == 0)
            {
                flag = 0;
                break;
            }
        }
        if (flag==1)
        {
            printf ("%d ",num);
        }

    }return 0;
}