C++ VS2008 基本写法

/*类成员的初始化: 求2点组成的矩形*/#include <iostream>using namespace std;class CCenterPoint{public:    CCenterPoint(int posX, int posY) : mPosX(posX), mPosY(posY)    {    }    void ShowPos() const    {        cout << "2点之间的中点坐标: (" << mPosX << "," << mPosY << ")" << endl;    }private:    int mPosX;    int mPosY;};class CArea{public:    CArea(int length, int width) : mLength(length), mWidth(width)    {    }    void ShowArea() const    {        cout << "2点组成的矩形面积: " << mLength * mWidth << endl;    }private:    int mLength;    int mWidth;};class CRect{public:    CRect(int posX1, int posY1, int posX2, int posY2)            : mPoint((posX1+posY1)/2, (posX2+posY2)/2),              mArea(posX2-posX1, posY2-posY1)    {    }    void Show() const    {        mPoint.ShowPos();        mArea.ShowArea();    }private:    CCenterPoint mPoint;    CArea mArea;};int main(){    CRect rect(10, 100, 20, 200);    rect.Show();    return 0;}