4、复制构造函数

/*
 *复制构造函数
 *用一个已知的对象初始化另一个对象
 */

#include <iostream>

using namespace std;

class test
{
private:
    int x, y;

public:
     test(int a, int b):x(a), y(b){}
     test(test( &c ));
     int getx(){return x;}
     int gety(){return y;}
};

test::test(test &c )//复制函数，注意这个形式
{
    x = c.x;
    y = c.y;
}


int main()
{// 复制构造函数其实是对象的复制
    test t1(11, 22);
    cout<<"x = "<<t1.getx()<<" , "<<"y = "<<t1.gety()<<endl;
    test t2(t1);
    cout<<"x = "<<t2.getx()<<" , "<<"y = "<<t2.gety()<<endl;
    return 0;
}


#include <iostream.h>

class Complex
{

public:
    Complex();
    Complex(double x, double y);
    Complex(Complex & c); //复制初始化构造函数

    double GetRel(){return rel;}
    double GetImg(){return img;}

private:
    double rel, img;
};

Complex::Complex()
{
    rel = 0; img = 0;
    cout<<"缺省构造函数被调用"<<endl;
}

Complex::Complex(double x, double y)
{
    rel = x; img = y;
    cout<<"构造函数被调用"<<endl;
}

Complex::Complex(Complex & c)
{
    rel = c.rel;
    img = c.img;
    cout<<"复制初始化构造函数被调用"<<endl;
}

Complex fun(Complex c)//复制构造函数的定义
{
    cout<<"在函数fun中"<<endl;
    double x,y;
    x = c.GetRel() * 10;
    y = c.GetImg() + 100;
    Complex x1(x, y);//调用构造函数
    return x1;
}

void main()
{
    Complex c1(6.8, 7.23), c2;//c1调用构造函数，c2调用缺省构造函数
    c2 = fun(c1);//c1 传到c调用复制构造函数，传到c2调用复制构造函数
    cout<<"("<<c2.GetRel()<<" ,"<<c2.GetImg()<<")"<<endl;
}