想半天了=，=

//计算球或圆锥或圆柱的体积
#include<stdio.h>
#define pi 3.1415926
int main()
{
int n;
void a(int cas);
scanf("%d",&n);
while(1){
if(n>3||n<1)
break;
else
a(n);
}
return 0;
}
void a(int cas)
{ double yuanzhu();
double yuanzhui();
double qiu();
switch(cas)
{
case'1':printf("%f",yuanzhu());break;
case'2':printf("%f",yuanzhui());break;
case'3':printf("%f",qiu());break;
default:break;
}
}
double yuanzhu()
{
double r;double h;double v;
scanf("%lf %lf",&r,&h);
v=pi*r*r*h;
return v;
}
double yuanzhui()
{
double r;double h;double v;
scanf("%lf %lf",&r,&h);
v=pi*r*r*h/3.0;
return v;
}
double qiu()
{
double r;double v;
scanf("%lf",&r);
v=4/3*pi*r*r*r;
return v;
}