class Line//線段類物件呼叫了下面的點類的物件來構成他
{
public:
Line(int x1,int y1,int x2,int y2);
~Line();
void setA(int x,int y);
void setB(int x,int y);
void printInfo();
private:
Coordinate m_coorA;
Coordinate m_coorB;

};

class Coordinate//點類的物件,定義點類的x,y
{
public:
Coordinate(int x,int y);
~Coordinate();
void setX(int x);
int getX();
void setY(int y);
int getY();
private:
int m_iX;
int m_iY;
};

Coordinate::Coordinate(int x,int y)
{
m_iX=x;
m_iY=y;
cout<<"Coordinate()::"<<m_iX<<","<<m_iY<<endl;
}


Coordinate::~Coordinate()
{
cout<<"~Coordinate()::"<<m_iX<<","<<m_iY<<endl;
}


void Coordinate::setX(int x)
{
     m_iX=x; 
} 
 
int Coordinate::getX()
{
     return m_iX;
} 


void Coordinate::setY(int y)
{
     m_iY=y;
} 


int Coordinate::getY()
{
    return m_iY;
} 


Line::Line(int x1,int y1,int x2,int y2)
:m_coorA(x1,y1),m_coorB(x2,y2)
{
cout<<"Line()"<<endl;
}


Line::~Line()
{
cout<<"~Line()"<<endl;
}

void Line::setA(int x,int y)
{
m_coorA.setX(x);
m_coorA.setY(x);
}


void Line::setB(int x,int y)
{
m_coorB.setX(x);
m_coorB.setY(x);
}


void Line::printInfo()
{
cout<<"("<<m_coorA.getX()<<","<<m_coorA.getY()<<")"<<endl;
cout<<"("<<m_coorB.getX()<<","<<m_coorB.getY()<<")"<<endl;
}


int main(void)
{
Line* p=new Line(1,2,3,4);//在堆區申請記憶體
p->printInfo();
delete p;
p=NULL;
return 0;

} 

1建構函式可以沒有引數,也可以有具體引數

2物件成員函式在棧區記憶體申請後可以自動回收,在堆區記憶體申請後需要手動回收(關鍵在於new不new)

3物件成員函式在程式中一般先呼叫點類的建構函式,再呼叫Line類的建構函式,析構時則相反