转 https://blog.youkuaiyun.com/thecape/article/details/82424093
//while循环
#include <stdio.h>
int main()
{
int i = 4;
while(i--)
{
printf("%d\n",i);
}
printf("循环结束\n");
printf("此时i=%d\n",i);
return 0;
}