成员函数调用

#include<iostream>using namespace std;class MyCircle{public:    double m_r;//半径    double m_s;//面积    double m_s = 3.14*m_r*m_r;    /*double getS()    {        m_s = 3.14*m_r*m_r;        return m_s;    }    */};int main(){    MyCircle c1, c2, c3;    double r1, r2, r3;    cout << "请输入c1圆形的半径r1：";    cin >> r1;    c1.setR(r1);    cout << "c1的圆面积：" << c1.getS() << endl;    cout << "请输入c2圆形的半径r2：";    cin >> r2;    c2.setR(r2);    cout << "c2的圆面积：" << c2.getS() << endl;    cout << "请输入c2圆形的半径r3：";    cin >> r3;    c3.setR(r3);    cout << "c3的圆面积：" << c3.getS() << endl;    system("pause");    return 0;}

double m_s = 3.14*m_r*m_r;
类中用来实现计算面积，将会垃圾数字
double m_r；定义半径是一随机值，计算面积时m_s=3.14*乱码*乱码，double m_s = 3.14*m_r*m_r；只在定义时执行一次，输出时直接拿来用，输出结果则出现乱码。

double getS()
{
m_s = 3.14*m_r*m_r;
return m_s;
}类中通过定义成员函数来进行调用，从而避免这种输出乱码的现象。