左移右移操作符重载

重载左移

#define _CRT_SECURE_NO_WARNINGS
#include<iostream>


using namespace std;

class C
{
public:
	C();
	C(int ta,int tb);
	~C();
	//友元重载左移<<运算符
	friend ostream & operator<<(ostream & cout, const C & another);

private:
	int a;
	int b;
};

//友元重载左移<<运算符
ostream & operator<<(ostream & cout, const C & another)
{
	cout << another.a << endl;
	cout << another.b << endl;
	cout << "==================" << endl;
	return cout;
}

C::C(int ta, int tb)
{
	a = ta;
	b = tb;
}

C::C()
{
}

C::~C()
{
}

int main(char *argv[], int argc)
{
	C a(1, 2),b(2,3);

	cout << a << b;

	return 0;
}

重载右移

#define _CRT_SECURE_NO_WARNINGS
#include<iostream>


using namespace std;

class C
{
public:
	C();
	C(int ta,int tb);
	~C();
	//友元重载左移<<运算符
	friend ostream & operator<<(ostream & cout, const C & another);
	//友元重载左移>>运算符
	friend istream & operator>>(istream &cin ,C & another);

private:
	int a;
	int b;
};
//友元重载右移>>运算符
istream & operator>>(istream & cin, C & another)
{
	cin >> another.a >> another.b;

	return cin;
}


//友元重载左移<<运算符
ostream & operator<<(ostream & cout, const C & another)
{
	cout << another.a << endl;
	cout << another.b << endl;
	cout << "==================" << endl;
	return cout;
}

C::C(int ta, int tb)
{
	a = ta;
	b = tb;
}

C::C()
{
}

C::~C()
{
}

int main(char *argv[], int argc)
{
	C a(1, 2),b(2,3);
	C c;
	cout << a << b;
	cin >> a >> c;

	cout << a << c;
	return 0;
}

只能用友元重载，如果用成员函数重载会出现顺序错误

ostream & operator<<(ostream & cout){
	cout << this->a << endl;
	cout << this->b << endl;
	return cout;
}

int main(){
    C a;
    //用成员重载<<或>> 会出现对象在左边的情况,所以不建议用成员函数来重载<<和>>运算符
    a << cout;
    return 0;
}