原创 linux下c++ lesson12 运算符重载基础教程

1-运算符重载概念.cpp

#include <iostream>

using namespace std;

class Complex
{
    //friend Complex operator+(const Complex &c1, const Complex &c2);
private:
    int a;    //实部
    int b;    //虚部
public:
    Complex(int _a, int _b)
    {
        this->a = _a;
        this->b = _b;
    }

    void print()
    {
        cout << a << " + " << b << "i" << endl;
    }

    Complex operator+(const Complex &c)
    {
        Complex t(0, 0);
        t.a = this->a + c.a;
        t.b = this->b + c.b;

        return t;
    }
};

//运算符重载本质就是函数的重载
/*Complex operator+(const Complex &c1, const Complex &c2)
{
    Complex t(0, 0);
    t.a = c1.a + c2.a;
    t.b = c1.b + c2.b;

    return t;
}*/

int main()
{
    Complex c1(1, 2);
    Complex c2(2, 3);

    c1.print();

    //c1 + c2;
    Complex t(0, 0);
    //t = operator+(c1, c2);
    t = c1 + c2;    //编译器会转换成  t = c1.operator+(c2)
    t.print();

    return 0;
}

2-重载输出运算符.cpp

#include <iostream>

using namespace std;

class Complex
{
    //friend Complex operator+(const Complex &c1, const Complex &c2);
    friend ostream &operator<<(ostream &out, const Complex &c);
private:
    int a;    //实部
    int b;    //虚部
public:
    Complex(int _a, int _b)
    {
        this->a = _a;
        this->b = _b;
    }

    void print()
    {
        cout << a << " + " << b << "i" << endl;
    }

    /*ostream &operator<<(ostream &out)     //如果左操作数不能修改，则不能重载成成员函数
    {
        out << this->a << " + " << b << "i";
        return out;
    }*/
};

//运算符重载本质就是函数的重载
/*Complex operator+(const Complex &c1, const Complex &c2)
{
    Complex t(0, 0);
    t.a = c1.a + c2.a;
    t.b = c1.b + c2.b;

    return t;
}*/

ostream &operator<<(ostream &out, const Complex &c)
{
    out << c.a << " + " << c.b << "i";
    return out;
}

int main()
{
    Complex c1(1, 2);
    c1.print();

    cout << c1 << endl;    //operator<<(operator<<(cout, c1), endl);   等价于 cout.operator<<(c1)

    return 0;
}

3-单目运算符重载.cpp

#include <iostream>

using namespace std;

class Complex
{
    friend ostream &operator<<(ostream &out, const Complex &c);
private:
    int a;    //实部
    int b;    //虚部
public:
    Complex(int _a, int _b)
    {
        this->a = _a;
        this->b = _b;
    }
    
    //后置++
    Complex operator++(int)   //通过占位参数来构成函数重载
    {
        Complex t = *this;
        this->a++;
        this->b++;
        return t;
    }

    //前置++
    Complex &operator++()
    {
        this->a++;
        this->b++;

        return *this;
    }
};

ostream &operator<<(ostream &out, const Complex &c)
{
    out << c.a << " + " << c.b << "i";
    return out;
}

int main()
{
    Complex c1(1, 2);

    cout << c1++ << endl;
    cout << ++c1 << endl;

    return 0;
}