#include <iostream>
#include <string>
using namespace std;class Person
{
public:Person(int age){m_Age=new int (age);}~Person(){if(m_Age!=NULL){delete m_Age;m_Age=NULL;}}//重载 赋值运算符Person& operator =(Person &p){//编译器提供深拷贝//m_Age=p.m_Age;//应该先判断是否有属性在堆区,如果有先释放干净,然后再深拷贝if(m_Age!=NULL){delete m_Age;m_Age=NULL;}//深拷贝m_Age=new int(*p.m_Age);return *this;}int *m_Age;
};void test01()
{Person p1(18);Person p2(20);Person p3(30);p3=p2=p1;//赋值操作cout<<"p1的年龄为: "<<*p1.m_Age<<endl;cout<<"p2的年龄为: "<<*p2.m_Age<<endl;cout<<"p3的年龄为: "<<*p3.m_Age<<endl;
}int main()
{test01();/*int a=10;int b=10;int c=10;c=b=a;//内置函数支持连等式cout<<"a= "<<a<<endl;cout<<"b= "<<b<<endl;cout<<"c= "<<c<<endl;*/system("pause");return 0;
}
师从黑马
运算符重载
概念:对已有的运算符重新进行定义,赋予另一种功能,以适应不同的数据类型
加号运算符重载
作用:实现两个自定义数据类型相加的运算
#include <iostream>
#include <string>
using namespace std;class Person
{
public://1、成员函数重载+号/* Person operator+(Person &p){Person temp;temp.m_A=this->m_A+p.m_A;temp.m_B=this->m_B+p.m_B;return temp;}
*/int m_A;int m_B;
};// 2、全局函数重载+号
Person operator+(Person& p1, Person& p2)
{Person temp;temp.m_A = p1.m_A + p2.m_A;temp.m_B = p1.m_B + p2.m_B;return temp;
}//函数重载的版本
Person operator+(Person &p1,int num)
{Person temp;temp.m_A = p1.m_A + num;temp.m_B = p1.m_B + num;return temp;
}void test01()
{Person p1;p1.m_A = 10;p1.m_B = 10;Person p2;p2.m_A = 10;p2.m_B = 10;//成员函数重载本质调用// Person p3=p1.operator+(p2);//全局函数的本质调用//Person p3=operator+(p1,p2);//简化Person p3 = p1 + p2;//运算符重载,也可以发生函数重载Person p4=p1+100;//Person +intcout << "p3.m_A= " << p3.m_A << endl;cout << "p3.m_B= " << p3.m_B << endl;cout << "p4.m_A= " << p4.m_A << endl;cout << "p3.m_B= " << p4.m_B << endl;
}int main()
{test01();system("pause");return 0;
}
对于内置的数据类型的表达式的运算符是不可能改变的
左移运算符重载
#include <iostream>
#include <string>
using namespace std;class Person
{friend ostream &operator<<(ostream &ut,Person &p);//利用成员函数重载 左移运算符 p.operator<<(cout) 简化版本 p<<cout//不会利用成员函数重载<<运算符,因为无法实现cout在左侧// void operator<<(cout)//{//}
public:Person(int a,int b){m_A=a;m_B=b;}private:int m_A;int m_B;
};//只能利用全局函数重载左移运算符
ostream &operator<<(ostream &ut,Person &p)//本质 operator<<(cout,p)简化cout<<P
{ut<<"m_A="<<p.m_A<<"m_B= "<<p.m_B;
}
void test01()
{Person p(10,10);cout<<p<<endl;
}int main()
{test01();system("pause");return 0;
}
递增运算符重载
作用:通过递增运算符重载,实现自己的整型数据
#include <iostream>
#include <string>
using namespace std;//自定义整型
class MyInteger
{friend ostream& operator<<(ostream& cout,MyInteger myint);
public:MyInteger(){m_Num=0;}//重载前置++运算符 返回引用为了一直对一个数据进行递增操作MyInteger& operator++(){//先进行++运算m_Num++;//再将自身做一个返回return *this;}//重载后置++运算符MyInteger operator++(int)//int 代表占位参数,可以用于区分前置递增和后置递增{//先 记录当时结果MyInteger temp=*this;//后 递增m_Num++;//最后将记录结果做返回return temp;}private:int m_Num;
};//重载<<运算符
ostream& operator<<(ostream& cout,MyInteger myint)
{cout<<myint.m_Num;return cout;
}
void test01()
{MyInteger myint;cout<<++myint<<endl;
}void test02()
{MyInteger myint;cout<<myint++<<endl;cout<<myint<<endl;}int main()
{test01();test02();system("pause");return 0;
}
前置递增返回的是引用,后置递增返回的是值
递减运算符重载
#include <iostream>
#include <string>
using namespace std;//自定义整型
class MyInteger
{friend ostream& operator<<(ostream& cout,MyInteger myint);
public:MyInteger(){m_Num=0;}//前置递减MyInteger& operator--(){m_Num--;return *this;}//后置递减MyInteger operator--(int){MyInteger temp=*this;m_Num--;return temp;}private:int m_Num;};
//重载<<运算符
ostream& operator<<(ostream& cout,MyInteger myint)
{cout<<myint.m_Num;return cout;
}
void test01()
{MyInteger myint;cout<<--myint<<endl;
}
void test02()
{MyInteger myint;cout<<myint--<<endl;cout<<myint<<endl;}int main()
{test01();test02();system("pause");return 0;
}
赋值运算符重载
C++编译器至少给一个类添加4个函数
1、默认构造函数 2、默认析构函数 3、默认析构函数,对属性进行值拷贝
4、赋值运算符operator=,对属性进行值拷贝
如果类中有属性指向堆区,做赋值操作时也会出现深浅拷贝的问题
关系运算符重载
作用:重载关系运算符,可以让两个自定义类型对象进行对比操作
#include <iostream>
#include <string>
using namespace std;class Person
{
public:Person(string name,int age){m_Name=name;m_Age=age;}//重载==bool operator==(Person &p){if(this->m_Name==p.m_Name&&this->m_Age==p.m_Age){return true;}return false;}bool operator!=(Person &p){if(this->m_Name==p.m_Name&&this->m_Age==p.m_Age){return false;}return true;}string m_Name;int m_Age;};void test01()
{Person p1("Tom",18);Person p2("Terry",18);if(p1==p2){cout<<"p1 和p2是相等的! "<<endl;}else{cout<<"p1和p2是不相等的!"<<endl;}if(p1!=p2){cout<<"p1和p2是不相等的!"<<endl;}else{cout<<"p1 和p2是相等的! "<<endl;}}
int main()
{test01();system("pause");return 0;
}
函数调用运算符重载
函数调用运算符()也可以重载
由于重载后使用的方式非常像函数的调用,因此称为仿函数
仿函数没有固定的写法,非常灵活
#include <iostream>
#include <string>
using namespace std;class MyPrint
{
public://重载函数调用运算符void operator()(string test){cout<<test<<endl;}
};void MyPrint02(string test)
{cout<<test<<endl;
}void test01()
{MyPrint myprint;myprint("hello world");//由于重载后使用的方式非常像函数的调用,因此称为仿函数MyPrint02("hello world");}//仿函数没有固定的写法,非常灵活//加法类
class MyAdd
{
public:int operator()(int num1,int num2){return num1+num2;}
};void test02()
{MyAdd myadd;int ret =myadd(100,100);cout<<"ret="<<ret<<endl;//匿名函数对象cout<<MyAdd()(100,100)<<endl;
}int main()
{test01();test02();system("pause");return 0;
}
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