#include <stdio.h>
int main()
{
    int y;
    double x;
    scanf("%lf",&x);
    if(x>0)
        y=1;
    if(x=0)
        y=0;
    if(x<0)
        y=-1;
    printf ("y=%d\n",y);
    return 0;
}
就是一个赋值吧
如果x＞0y=1
x<0y=-1
x=0y=0

输入0不行