求教关于C语言的问题(01)

[小沈C]

求 x>0,y=1/x;
x<0,y=-1/(2*x);
x=0,y=0;

main(){
double x,y1,y2;
printf("input x:\n");
scanf("%lf",&x);
if(x>0)
y1=1/x;
printf("the result is %lf",y1);
else if(x<0)
y2=-1/(2*x);
printf("the result is %lf",y2);
else
y=0;
printf("the result is zero");
}
为什么我compile：syntax error before "else" 明显printf后面有；号的啊

[shijinpeng_2012]

把该加的括号都加上试下

[xgbing]

main(){
double x,y1,y2;
printf("input x:\n");
scanf("%lf",&x);

if(x>0)
{
y1=1/x;
printf("the result is %lf",y1);
}
else if(x<0)
{ y2=-1/(2*x);
printf("the result is %lf",y2);
}
else
{ y=0;
printf("the result is zero");
}
}

[Corner]

    double x,y,y1,y2;
    printf("input x:\n");
    scanf("%lf",&x);
    if(x>0)
    {
        y1=1/x;
        printf("the result is %lf",y1);
    }
    else if(x<0)
    {
        y2=-1/(2*x);
        printf("the result is %lf",y2);
    }
    else
    {     
        y=0;
        printf("the result is zero");
    }

if else while等语句不加括号仅会包含其后的一条语句

[viqjatdw2009]

把要判断的语句都用{}括起来