作业：

实现关系运算符重载（仅>,<,==）：

#include <iostream>using namespace std;class Person
{int a;int b;friend bool operator== (const Person &L,const Person&R);
public:Person(){}Person(int a,int b):a(a),b(b){}bool operator> (const Person&R)const{if(a>R.a&&b>R.b){return true;}else{return false;}}bool operator< (const Person&R)const{if(a<R.a&&b<R.b){return true;}else{return false;}}
};
bool operator== (const Person &L,const Person&R)
{if(L.a==R.a&&L.b==R.b){return true;}else{return false;}
}int main()
{Person p1(10,10),p2(10,10),p3(20,20);if((p1>p2)==true){cout << "p1大于p2" << endl;}elsecout << "p1不大于p2" << endl;if((p1==p2)==true){cout << "p1等于p2" << endl;}elsecout << "p1不等于p2" << endl;if((p1<p2)==true){cout << "p1小于p2" << endl;}elsecout << "p1不小于p2" << endl;if((p2>p3)==true){cout << "p2大于p3" << endl;}elsecout << "p2不大于p3" << endl;if((p2==p3)==true){cout << "p2等于p3" << endl;}elsecout << "p2不等于p3" << endl;if((p2<p3)==true){cout << "p2小于p3" << endl;}elsecout << "p2不小于p3" << endl;return 0;
}

拷贝赋值函数实例：

#include <iostream>using namespace std;
class stu
{string name;int age;
public:void show (){cout << name << age << endl;}stu(string name,int age):name(name),age(age){cout << "这是stu的构造函数" << endl;}stu(stu &other):name(other.name),age(other.age)//构造函数，需要初始化列表{cout << "这是stu的拷贝构造函数" << endl;}stu& operator=(const stu& other)//拷贝赋值函数，不需要初始化列表{if(this != &other)//避免自己被赋值给自己{name=other.name;age=other.age;}cout <<"这是stu的拷贝赋值函数"  << endl;return *this;}~stu(){cout << "这是stu的析构函数" << endl;}
};int main()
{stu s1("张三",20);stu s2=s1;stu s3("",0);s3=s2;return 0;
}

 

 匿名对象实例：

#include <iostream>using namespace std;
class stu
{string name;int age;
public:stu(string name,int age):name(name),age(age){cout << "这是stu的构造函数" << endl;}stu(const stu& other):name(other.name),age(other.age){cout << "这是stu的拷贝构造函数" << endl;}stu& operator=(const stu& other){name=other.name;age=other.age;return *this;}~stu(){cout <<"这是stu的析构函数" << endl;}
};int main()
{stu s1=stu("张三",20);//用匿名类做赋值操作stu s[3]={stu("a",1),stu("b",2),stu("c",3)};//用匿名类做类数组的赋值操作return 0;
}

 友元实例:

#include <iostream>using namespace std;class Room
{friend void good(Room &s);//声明good函数是友元函数，就可以调用本类中的所有成员friend class bad;//声明bad类是友元，bad类就可以调用本类中的所有成员string badroom;
public:string livingroom;Room(string badroom,string livingroom):badroom(badroom),livingroom(livingroom){cout<< "这是Room的构造函数" << endl;}Room()//无参构造{}
};
void good(Room &s)
{cout << s.livingroom << endl;cout << s.badroom <<endl;
}
class bad
{
public:Room s1;void visit(){cout << s1.badroom << endl;//调用s1中的私有成员cout << s1.livingroom <<endl;}};int main()
{Room s("卧室","客厅");good(s);bad a;return 0;
}

常成员和常对象实例:

#include <iostream>using namespace std;class Stu
{string name;mutable int age;//加了mutable，就可以在常成员函数中修改
public:Stu()//无参构造函数{}Stu(string n,int a):name(n),age(a)//有参构造类型{ }void show()const//常成员函数，不做修改{age=30;//会报错，因为是const类型的成员函数，不能做修改,当age加了mutable，就变成可以在常成员函数中修改cout << "名字是:" << name << endl;cout << "年龄是:" << age << endl;}void show()//非常成员函数{age=25;cout << "名字是:" << name << endl;cout << "年龄是:" << age << endl;}
};int main()
{Stu s1("张三",18);//非常对象s1.show();//有常成员函数和非常成员函数，优先调用非常成员函数，只有常成员函数，调用常成员函数const Stu s2("里斯",20);//常对象s2.show();//调用常成员函数，年龄不会发生改变//当只有非常成员函数时，s2无法调用非常成员函数return 0;
}

算数运算符重载:

 

#include <iostream>using namespace std;class Person
{friend const Person operator+(const Person &L,const Person &R);friend const Person operator>(const Person &L,const Person &R);int a;int b;
public:Person(){};Person(int a,int b):a(a),b(b){}
//    const Person operator+(const Person &R)
//    {
//        Person temp;
//        temp.a=a+R.a;
//        temp.b=b+R.b;
//        return temp;
//    }void show(){cout << "a = " << a << endl;cout << "b = " << b << endl;}
};
const Person operator+(const Person &L,const Person &R)//全局
{Person temp;temp.a = L.a + R.a;temp.b = L.b + R.b;return temp;
}
const Person operator>(const Person &L,const Person &R)
{Person temp;temp.a = (L.a > R.a) ? L.a : R.a;temp.b = (L.b > R.b) ? L.b : R.b;return temp;
}
int main()
{Person p1(10,10);Person p2(10,10);Person p3=p1+p2;//假设调用类内的运算符重载，本质:p3=p1.operator+(p2)p3.show();Person p4=p2+p3;//假设调用类外的运算符重载，本质:p4=operator(p2,p3)p4.show();Person p5(5,11);Person p6;p6 = p5 > p1;p6.show();return 0;
}