//lab2_3.cpp
#include <iostream>
using namespace std ;
const float PI = 3.1416;
void main()
{
int iTpye;
float radius,a,b,area;
cout << "图形的类型为?(1-圆形 2-长方形 3-正方形):";
cin >> iTpye;
switch(iTpye)
{
case 1:
cout << "圆的半径为: ";
cin >> radius;
area = PI * radius * radius;
cout << "面积为:" << area << endl;
break;
case 2:
cout<<"矩形的长为: ";
cin >> a;
cout << "矩形的宽度为: ";
cin >> b;
area = a * b;
cout << "面积为:" << area << endl;
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!:<<endl;
}
}
參考答案:cout << "不是合法的输入!:<<endl;
}
标点错了……
把：改成”——cout << "不是合法的输入!”<<endl;
还有，PI的声明最好用double，防止结果不精确
试试！应该可以了。
