#include <stdio.h>
int main()
{
    char t ;
L1:    printf("are you pig?\n");
//    scanf("%c" , &t );
    while (1)
    {
        if((t = getchar()) != 'Y')
            goto L1;
        else
            break;
    }
    return 0 ;
}

运行结果就是这个：
are you pig?
n
are you pig?
are you pig?
d
are you pig?
are you pig?
Y
Press any key to continue

[ 本帖最后由 luoye1994 于 2015-7-27 13:47 编辑 ]

getchar 跟scanf不能同用，或者把getchar改为putchar：
#include <stdio.h>
int main()
{
    char t;
L1:    printf("are you pig?\n");
//    scanf("%c" , &t );
    while (1)
    {
        if((t = getchar()) != 'N')
    {
        fflush(stdin);   
            goto L1;
    }
        else
            break;
    }
    return 0 ;
}
这样就好了!
谢了