运算符重载

这里面东西还挺多，先写点，以后慢慢补充吧
operator++(a); //++a
operator++(a,int);//a++,int是一个哑元常量值

Bird

#include<iostream>
using namespace std;

class Bird{
public:
	string s;
	static int i;
	int num;
public:
	Bird(string str);
	Bird(const Bird& bird);
};

const Bird& operator+(Bird& bird1,const Bird& bird2){
	bird1.num+=bird2.num;
	return bird1;
}
const Bird& operator-(Bird& bird1,const Bird& bird2){
	bird1.num-=bird2.num;
	return bird1;
}
const Bird& operator*(Bird& bird1,const Bird& bird2){
	bird1.num*=bird2.num;
	return bird1;
}
const Bird& operator/(Bird& bird1,const Bird& bird2){
	bird1.num/=bird2.num;
	return bird1;
}

class BirdHouse{
public:
	int num;
public:
	BirdHouse(Bird bird1,Bird *bird2,const Bird& bird3){cout << "constructor" << endl;}
	BirdHouse(const BirdHouse& birdHouse){cout << "bird house copy constructor!"<< endl;}
	const BirdHouse& operator=(const BirdHouse& bh){cout << "operator=" << endl;return bh;}
	const BirdHouse& operator+(const BirdHouse& bh){
		num+=bh.num;
		return *this;
	}
	const BirdHouse& operator-(const BirdHouse& bh){
		cout << "operator-" << endl;
		num-=bh.num;
		return *this;
	}
	const BirdHouse& operator*(const BirdHouse& bh){
		num*=bh.num;
		return *this;
	}
	const BirdHouse& operator/(const BirdHouse& bh){
		num/=bh.num;
		return *this;
	}
};

int Bird::i = 0;

Bird::Bird(string str):s(str)
{
}

Bird::Bird(const Bird& bird)
{
	cout << "bird copy constructor!" << endl;
}

ostream& operator<<(ostream& os,const Bird& bird)
{
	os << bird.s << " #" << bird.i << endl;
	return os;
}


int main()
{
	Bird bird("small");
	bird.num = 10;
	cout << bird << endl;
	Bird bird2(bird);
	bird2.num = 5;
	cout << bird2 << endl;
	Bird bird3("big");
	cout << "test bird house:" << endl;
	BirdHouse bh1(bird,&bird2,bird3);
	BirdHouse bh2(bh1);
	bh2 = bh1;
	cout << "test operator:" << endl;
	bird = bird-bird2;
	cout << bird.num << endl;
	bh1.num = 20;
	bh2.num = 30;
	bh1*bh2;
	cout << bh1.num << endl;
	cout << bh2.num << endl;
}

重载new,delete,一般不推荐

#include<iostream>
using namespace std;

class A{
public:
    void* operator new(size_t){ //must:void*,size_t
        cout << "new operator!" << endl;
    }
    void* operator new(size_t,string s){//attention
        cout << "operator new!" << s << endl;
    }
    void operator delete(void* l){
        cout << "delete operator!" << endl;
    }
};

class B{
public:
    void* operator new[](size_t){
        cout << "new arrar!" << endl;
    }

    void operator delete[](void *l){
        cout << "delete array!" << endl;
    }
};

int main()
{
    string str = "abc";
    A* a1 = new A;
    delete a1;
    A* a2 = new (str) A();//attention
    delete a2;
    B* b = new B[10];
    delete []b;//[] must before b
}