#include<iostream> using namespace std;

const float PI=3.1416; void mian() { int iType; float radius,a,b,area;

cout<<"图形的类型？（1-圆形 2-长方形 3-正方形）:"; cin>>iType; switch(iType) { case 1: cout<<"圆的半径为："; cin>>radius; area=PI*radius; cout<<"面积为："<<area<<endl; break; case 2: cout<<"矩形的长为："; cin>>a; cout<<"矩形的宽为："; cin>>b; area=a*b; cout<<"面积为："<<area<<endl; break; case 3: cout<<"正方形的边长为："; cin>>a; area=a*a; cout<<"面积为："<<area<<endl; break; default: cout<<"不是合法的输入值！"<<endl; } }