实验10-1 圆形体体积计算器（20 分）

#include <stdio.h> 
#include <stdlib.h> 
#include <math.h>  
#define PI 3.141592654 
void cal(int sel); 
int main(void) 
{      
	int sel;    
	while(1){               
		 printf("1-Ball\n");              
		 printf("2-Cylinder\n");               
		 printf("3-Cone\n");              
		 printf("other-Exit\n");              
		 printf("Please enter your command:");               
		 scanf("%d",&sel);
		if(sel<1||sel>3)                
			break;             
		else              
		cal(sel);            
	}              
	return 0; 
}  
void cal(int sel) {    
	double vol_ball(void);  
	double vol_cylind(void);  
	double vol_cone(void);      
	switch(sel)
	{               
		case 1:                 
		printf("球体积为:%.2f\n",vol_ball());        
		break;         
		case 2:      
		printf("圆柱体积为:%.2f\n",vol_cylind());             
		break;             
		case 3:          
		printf("圆锥体积为:%.2f\n",vol_cone());             
		break;                
	} 
}  
double vol_ball() 
{   
	double r;    
	printf("Please enter the radius::");   
	scanf("%lf",&r);      
	return (4.0/3.0*PI*r*r*r); 
}  
double vol_cylind() 
{       
	double r,h;  
	printf("Please enter the radius and the height:");  
	scanf("%lf%lf",&r,&h);      
	return (PI*r*r*h); 
} 
double vol_cone()
{ 
	double r,h;  
	printf("Please enter the radius and the height:");    
	scanf("%lf%lf",&r,&h);      
	return (PI*r*r*h/3.0);
}