素数的判断

#include <stdio.h>
#include <math.h>

int main(int argc, char* argv[])
{
    int m,i,k;
    printf("please input the integer number:\n");
    scanf("%d",&m);
    k=(int)sqrt(m);
    for (i=2;i<=k;i++)
    {
        if (m%i==0)
        {
            break;
        }
    }
    if (i>k)
    {
        printf("%d is a prime number \n",m);
    } 
    else
    {
        printf("%d is not a prime number \n",m);
    }
    return 0;
}

注意i++到后面可能会变成

i＝k+1