c++运算符重载

C++不允许把下标运算符函数作为外部函数来定义,它只能是非静态的成员函数。

注意操作符重载作为友元函数和成员函数的区别

// person.cpp : 定义控制台应用程序的入口点。
//

#include "stdafx.h"
#include <iostream>
#include <string>
#include <sstream>
using namespace std;

class MyShape {
protected:
	int R_, G_, B_;

	string colorToString() {
		stringstream ss;
		ss << R_ << " " << G_ << " " << B_;
		return ss.str();
	}
public:
	void setColor(int R, int G, int B) {
		R_ = R; G_ = G, B_ = B;
	}
	int getR() {
		return R_;
	}
	int getG() {
		return G_;
	}
	int getB() {
		return B_;
	}
	virtual void Draw() = 0;
	MyShape() {
		R_ = 255; G_ = 255, B_ = 255;
	}
};

class MyCircle : public MyShape{
private:
	int x_, y_, radius_, _size;
	MyCircle*mMyCircle;
public:
	MyCircle(int x, int y, int radius) {
		x_ = x;
		y_ = y;
		radius_ = radius;
		mMyCircle = NULL;
	}
	MyCircle(int size) {
		_size = size;
		mMyCircle = new MyCircle[size];
	}
	MyCircle() {
		x_ = y_ = 200;
		radius_ = 100;
		mMyCircle = NULL;
	}

	MyCircle(MyCircle& aCircle) {
		x_ = aCircle.x_;
		y_ = aCircle.y_;
		radius_ = aCircle.radius_;
		R_ = aCircle.getR();
		G_ = aCircle.getG();
		B_ = aCircle.getB();
		mMyCircle = NULL;
	}
	~MyCircle()
	{
		if (mMyCircle != NULL)
		delete[]mMyCircle;
	}
	void setCenter(int x, int y) {
		x_ = x;
		y_ = y;
	}

	void setRadius(int radius) {
		radius_ = radius;
	}
	int getRadius() {
		return radius_;
	}

	void Draw() {
	}

	//----在此处添加关系运算符  >、<、>=、<=、==、!=  的重载原型声明
	friend bool operator>(const MyCircle &c1, const MyCircle &c2)//声明为友元函数
	{
		return c1.radius_ > c2.radius_;
	}



	bool operator<(const MyCircle &c1)
	{
		return this->radius_ < c1.radius_;
	}
	bool operator>=(const MyCircle &c1)
	{
		return this->radius_ >= c1.radius_;
	}
	bool operator<=(const MyCircle &c1)
	{
		return this->radius_ <= c1.radius_;
	}
	bool operator==(const MyCircle &c1)
	{
		return this->radius_ == c1.radius_;
	}
	bool operator!=(const MyCircle &c1)
	{
		return this->radius_ != c1.radius_;
	}

	MyCircle operator++()
	{
		radius_++;
		return *this;
	}
	MyCircle operator++(int dummy)
	{
		MyCircle temp(*this);
		radius_++;
		return temp;
	}
	MyCircle& operator[](const int &index)//不允许声明为友元函数
	{
		return mMyCircle[index];
	}

};

//----在此处添加关系运算符的重载定义



int _tmain(int argc, _TCHAR* argv[])
{
	int r1, r2, r3 = 0;
	cin >> r1 >> r2 >> r3;
	MyCircle c1, c2, c3;
	c1.setRadius(r1);
	c2.setRadius(r2);
	c3.setRadius(r3);
	if (c1 > c2)
		cout << 1 << endl;
	if (c2 < c1)
		cout << 5 << endl;

	MyCircle aa(4);
	for (int i = 0; i < 4; i++)
	{
		aa[i] = MyCircle(1, 2, i + 1);
		cout << aa[i].getRadius();
	}
	system("pause");
	return 0;
}