.5 运算符重载
运算符重载概念：对已有的运算符重新进行定义，赋予其另外一种功能，以适应不同的数据类型
4.5.1 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
1 #include<iostream>2 using namespace std;3 //加号运算符重载4 class Person5 {6 public:7 //成员函数重载+号8 Person operator+(Person &p)9 {10 Person temp;11 temp.m_A = p.m_A + this->m_A;12 temp.m_B = p.m_B + this->m_B;13 return temp;14 }15 int m_A;16 int m_B;17 };18 19 //全局函数重载20 Person operator+(Person &p1,Person &p2)21 {22 Person temp;23 temp.m_A = p1.m_A + p2.m_A;24 temp.m_B = p1.m_B + p2.m_B;25 return temp;26 }27 void test01()28 {29 Person p1;30 p1.m_A = 10;31 p1.m_B = 10;32 Person p2;33 p2.m_A = 10;34 p2.m_B = 10;35 36 Person p3 = p1 + p2;37 //成员函数重载的本质38 Person p3 = p1.operator+(p2);39 //全局函数重载的本质40 Person p5 = operator+(p1,p2);41 cout << p3.m_A << " " << p3.m_B<<endl;42 }43 //1.成员函数重载+号44 int main(int argc, const char *argv[])45 {46 test01();47 return 0;48 }4.5.2 左移运算符重载
1 #include<iostream>2 using namespace std;3 4 //左移5 class Person6 {7 public:8 //内置重载函数 左移运算符9 //实现不了10 int m_A;11 int m_B;12 };13 14 //全局重载函数15 void operator<<(ostream &cout ,Person &p)16 {17 cout << "m_A = " << p.m_A << "m_B = " <<p.m_B << endl;18 }19 20 void test01()21 {22 Person p;23 p.m_A = 10;24 p.m_B = 10;25 26 cout << p.m_A <<endl;27 }28 int main(int argc, const char *argv[])29 {30 test01();31 return 0;32 }
4.5.3递增运算符重载
作用：通过重载递增运算符，实现自己的整型数据
#include<iostream>using namespace std;class Myinterger{friend ostream & operator<<(ostream &cout,Myinterger myint);public://重载前置++函数//返回引用是为了一直对一个数据进行递增操作Myinterger& operator++(){m_Num++;return *this;}//重载后置++函数//int 是占位参数Myinterger operator++(int){//先记录当时结果Myinterger temp = *this;m_Num++;return temp;}Myinterger(){m_Num = 0;}private:int m_Num;};//重载<<运算符ostream& operator<<(ostream &cout,Myinterger myint){cout << myint.m_Num;return cout;}void test01(){Myinterger myint;++myint;cout << myint << endl;}int main(int argc, const char *argv[]){test01();return 0;}
4.5.4 赋值运算符重载
1.编译器至少给一个类添加4个函数
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默认构造函数（无参，函数为空）
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默认析构函数（无参，函数为空）
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默认拷贝构造函数，对属性进行值拷贝
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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，做赋值操作时会出现深浅拷贝问题
#include<iostream>using namespace std;class Person{public://等号重载函数Person& operator=(Person &p){//实现浅拷贝//先判断是否有属性在堆区，先释放在深拷贝if (m_age != NULL){delete m_age;m_age = NULL;}m_age = new int(*p.m_age);return *this;}Person(int age){m_age = new int(age);}int *m_age;~Person(){if (m_age != NULL){delete m_age;}}};void test01(){Person p1(18);Person p2(12);p2 = p1;cout << "p1的年龄为："<<*p1.m_age<<endl;cout << "p1的年龄为："<<*p2.m_age<<endl;}int main(int argc, const char *argv[]){test01();return 0;}4.5.5 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://重载==bool operator==(Person &p){if (m_name == p.m_name && m_age == p.m_age){return true;}return false;}Person(string name , int age){m_name = name;m_age = age;}private:string m_name;int m_age;};void test01(){Person p1("zyl",18);Person p2("zyl",18);bool b = (p1==p2);cout << b << endl;}int main(int argc, const char *argv[]){test01();return 0;}4.5.6 函数调用运算符重载
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函数调用运算符()也可以重载
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由于重载后使用的方式非常想函数的调用，因此也成为仿函数
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仿函数你没有固定写法，非常灵活
#include<iostream>#include<string>using namespace std;class MyPrint{public:void operator()(string text){cout << text <<endl;}};void test01(){MyPrint mp;mp("hello");//仿函数}int main(int argc, const char *argv[]){test01();return 0;}
