C++——运算符重载

运算符重载编程基础

 

例如:

    //全局函数 完成 +操作符 重载  Complex operator+(Complex &c1, Complex &c2)

//类成员函数 完成 -操作符 重载   Complex operator-(Complex &c2)

 

#include <iostream>
using namespace std;

class Complex
{
public:
    int a;
    int b;
public:
    Complex(int a=0, int b=0)
    {
        this->a = a;
        this->b = b;
    }
    void printCom()
    {
        cout<<a<<" + " << b << "i" <<endl;
    }
};

//2 函数名 升级
Complex operator+(Complex &c1, Complex &c2)
{
    cout<<"12345上山 打老虎"<<endl;
    Complex tmp(c1.a + c2.a, c1.b+ c2.b);
    return tmp; //
}

void main()
{
    
    int a = 0, b = 0;
    int c;
    c = a + b; //1 基础数据类型 编译器已经知道了. 如何运算

    // a + bi 复数运算规则
    Complex c1(1, 2), c2(3, 4);
    Complex c3; //2 类 也是一种数据类型  用户自定义数据类型 C++编译器 是不知道如何进行运算
    
    //步骤3 
    Complex c4 = c1 + c2;
    c4.printCom();


    //总结: 1 运算符重载的本质 是 函数调用 

    cout<<"hello..."<<endl;
    system("pause");
    return ;
}

 二、实列

#include <iostream>
using namespace std;

/*
class ostream
{

};
*/

class Complex
{
private:
    int a;
    int b;
    //friend void operator<<(ostream &out, Complex &c1);
    friend ostream& operator<<(ostream &out, Complex &c1);

public:
    Complex(int a=0, int b=0)
    {
        this->a = a;
        this->b = b;
    }
    void printCom()
    {
        cout<<a<<" + " << b << "i" <<endl;
    }
public:

    //实现 + 运算符重载
    Complex operator+(Complex &c2)
    {
        Complex tmp(a + c2.a, b + c2.b);
        return tmp;
    }

    //前置++
    Complex& operator++()
    {
        a++;
        b++;
        return *this;
    }

    //后置++
    Complex operator++(int)
    {
        //先使用 在让c1加加
        Complex tmp = *this;
        //return c1;
        this->a ++;
        this->b ++;
        return tmp;
    }
    //成员函数法 实现 -运算符重载
     Complex operator-(Complex &c2)
    {
        Complex tmp(this->a - c2.a, this->b - c2.b);
        return tmp;
    }

     //前置--
    Complex& operator--()
    {
        this->a --;
        this->b --;
        return *this;
    }

    //后置--
    Complex operator--(int)
    {
        Complex tmp = *this;
        this->a--;
        this->b--;
        return tmp;
    }
};


void main31()
{
    Complex c1(1, 2), c2(3, 4);

    //1    全局函数法 实现 + 运算符重载
    // Complex operator+(Complex &c1, Complex &c2);
    Complex c3 = c1 + c2;
    c3.printCom();

    //2 成员函数 法 实现 -运算符重载
    //c1.operator-(c2);
    //Complex operator-(Complex &c2)
    Complex c4 = c1 - c2;
    c4.printCom();

    //前置++操作符 用全局函数实现
    ++c1;
    c1.printCom();

    //前置--操作符 成员函数方法
    --c1;
    c1.printCom();
    //Complex& operator++(Complex &c1)
    //c1.operator--();

    //后置++操作符 用全局函数实现
    c1++;
    c1.printCom();

    //后置--操作符 用成员函数实现
    c1--;
    c1.printCom();
    //c1.operator--()
    
    cout<<"hello..."<<endl;
    system("pause");
    return ;
}

/*
void operator<<(ostream &out, Complex &c1)
{
    out<<"12345 生活真是苦"<<endl;
    out<<c1.a << " + " << c1.b << "i" << endl;
}
*/

ostream& operator<<(ostream &out, Complex &c1)
{
    out<<"12345 生活真是苦"<<endl;
    out<<c1.a << " + " << c1.b << "i" << endl;
    return out;
}

void main()
{
    int a = 10;
    Complex c1(1, 2), c2(3, 4);
    cout<<a<<endl; //按照数据类型 

    //1
    cout << c1 ;
    //2 ostream 类中 添加 成员函数 .operator<<
    //ostream
    //cout.operator<<(c1);

    //2 函数返回值当左值 需要返回一个引用
    cout << c1  << "aaddddd";
    //
    //cout.operator<<(c1) .operator<<("aaddddd");
    //void.operator<<("aaddddd");

    system("pause");
}