#include<stdio.h>
int main()
{
    int a,i;
    printf("please input an ingeter:");
    scanf("%d",&a);
        for(i=2;i<a;i++)
            if(a%i==0)
            printf("%d不是素数",a);
            else
            printf("%d是素数",a);
    return(0);
}

这是我写的判断素数的算法；每输入一个数要执行好多次，怎样跳出循环？？？

https://bbs.bccn.net/search.php?searchid=79&orderby=lastpost&ascdesc=desc&searchsubmit=yes

用break语句啊
for(i=2;i<a;i++){
if(a%i==0)
break;
else if(i>=a)
printf("%d是素数",a);
}

#include<stdio.h>
int main()
{
    int a,i;
    printf("please input an ingeter:");
    scanf("%d",&a);
    for(i=2;i<a;i++)
        if(a%i==0)
            break ;
    if ( i < a )
        printf("%d不是素数",a);
    else
        printf("%d是素数",a);
    return(0);
}

受教

Too bad, why don't you write the code like this:

#include <stdio.h>
int main()
{
   int num;
   printf("Please input a number: \n");
   scanf("%d", &num);
   if(num % 2 == 0)
   {
      printf("The Number is a even. \n");
   }
   else
   {
      printf("The Number is a odd. \n");
   };
   return 0;
};