c++-重载运算符（+-，++，--，+=，-=，cin，cout）

操作符重载

• 自定义类型需要操作符重载
• 运算符重载入门技术推演
• 友元函数和成员函数实现2元运算符重载
• 友元函数和成员函数实现1元运算符重载（前置++，前置--，后置++，后置--）
• 友元函数实现运算符重载应用场景

#define _CRT_SECURE_NO_WARNINGS
#include <iostream>

using namespace std;

class Complex
{
public:
	Complex(int a, int b)
	{
		this->a = a;
		this->b = b;
	}

	void printComplex()
	{
		cout << "( " << this->a << ", " << this->b << "i )" << endl;
	}

	friend Complex complexAdd(Complex &c1, Complex &c2);
	//friend Complex operator+(Complex &c1, Complex &c2);
	//friend Complex  operator-(Complex &c1, Complex &c2);

	Complex complexAdd(Complex &another)
	{
		Complex temp(this->a + another.a, this->b + another.b);
		return temp;
	}

	Complex operator+(Complex &another)
	{
		Complex temp(this->a + another.a, this->b + another.b);
		return temp;
	}
	Complex operator-(Complex &another)
	{
		Complex temp(this->a - another.a, this->b - another.b);
		return temp;
	}

private:
	int a;//实数
	int b;//虚数
};

Complex complexAdd(Complex &c1, Complex &c2)
{
	Complex temp(c1.a + c2.a, c1.b + c2.b);
	return temp;
}

//操作符重载写在全局
#if 0
Complex operator+(Complex &c1, Complex &c2)
{
	Complex temp(c1.a + c2.a, c1.b + c2.b);
	return temp;
}

Complex operator-(Complex &c1, Complex &c2)
{
	Complex temp(c1.a - c2.a, c1.b - c2.b);
	return temp;
}

#endif

int main(void)
{
	Complex c1(1, 2);
	Complex c2(2, 4);

	c1.printComplex();
	c2.printComplex();

	//Complex c3 = complexAdd(c1, c2);
	//Complex c3 = c1.complexAdd(c2);
	//Complex c3 = c1 + c2; //operator+(c1, c2)  全局的调用方式
						//c1.operator+(c2)
	//Complex c3 = operator+(c1, c2);

	Complex c3 = c1.operator+(c2);

	c3.printComplex();

	Complex c4 = c1 + c2;

	c4.printComplex();

	return 0;
}

双目运算符重载(-=,+=)

#define _CRT_SECURE_NO_WARNINGS
#include <iostream>

using namespace std;

class Complex
{
public:
	Complex(int a, int b)
	{
		this->a = a;
		this->b = b;
	}

	void printComplex()
	{
		cout << "( " << this->a << ", " << this->b << "i )" << endl;
	}

	//friend Complex & operator+=(Complex &c1, Complex &c2);
	friend Complex &operator-=(Complex &c1, Complex &c2);

	Complex &operator+=(Complex &another)
	{
		this->a += another.a;
		this->b += another.b;

		return *this;
	}
private:
	int a;//实数
	int b;//虚数
};

//全局
#if 0
Complex & operator+=(Complex &c1, Complex &c2)
{
	c1.a += c2.a;
	c1.b += c2.b;

	return c1;
}
#endif

Complex &operator-=(Complex &c1, Complex &c2)
{
	c1.a -= c2.a;
	c1.b -= c2.b;

	return c1;
}

int main(void)
{
	Complex c1(1, 2);
	Complex c2(2, 4);

	(c1 += c2)+=c2;//c1.operator+=(c2)  .operator(c2)

	c1.printComplex();
	c2.printComplex();

	c1 -= c2;
	c1.printComplex();

	return 0;
}

单目运算符

#define _CRT_SECURE_NO_WARNINGS
#include <iostream>

using namespace std;

class Complex
{
public:
	Complex(int a, int b)
	{
		this->a = a;
		this->b = b;
	}

	void printComplex()
	{
		cout << "( " << this->a << ", " << this->b << "i )" << endl;
	}

	//friend Complex & operator++(Complex &c);
	//friend const Complex operator++(Complex &c1, int);

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

		return *this;
	}

	const Complex operator++(int)//亚元
	{
		Complex temp(this->a, this->b);
		this->a++;
		this->b++;
		return temp;
	}

private:
	int a;//实数
	int b;//虚数
};

#if 0
//重载的是前++运算符
Complex & operator++(Complex &c)
{
	c.a++;
	c.b++;
	return c;
}
#endif

//重载的是后++运算符
#if 0
const Complex operator++(Complex &c1, int)
{
	Complex temp(c1.a, c1.b);

	c1.a++;
	c1.b++;

	return temp;
}
#endif

int main(void)
{

	Complex c1(1, 2);

	//++++c1;

	c1++;

	c1.printComplex();

	//++++c1;

	return 0;
}

左移右移操作符重载

#define _CRT_SECURE_NO_WARNINGS
#include <iostream>

using namespace std;

class Complex
{
public:
	Complex(int a, int b)
	{
		this->a = a;
		this->b = b;
	}

	void printComplex()
	{
		cout << "( " << this->a << ", " << this->b << "i )" << endl;
	}

	friend ostream& operator<<(ostream & os, Complex &c);
	friend istream & operator>>(istream &is, Complex &c);

	//<<操作符只能写在全局，不能够写在成员方法中。否则调用的顺序会变饭，c1<<cout;
#if 0
	ostream& operator<<(ostream &os) //c1.operator<<(cout)
	{
		os << "( " << this->a << ", " << this->b << "i )";
		return os;
	}
#endif

private:
	int a;//实数
	int b;//虚数
};

#if 1
ostream& operator<<(ostream & os, Complex &c)
{
	os << "( " << c.a << ", " << c.b << "i )";

	return os;
}

istream & operator>>(istream &is, Complex &c)
{
	cout << "a:";
	is >> c.a;
	cout << "b:";
	is >> c.b;

	return is;
}
#endif

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

	cin >> c1;//operaotr>>(cin, c1)

	cout << c1;
	//c1 << cout;
	//cout.operator<<(c1);

	//cout << c1 << "   " <<c1<< endl;//operator<<(cout, c1);

	return 0;
}