C++6种运算符重载详解

运算符重载概念：对已有的运算符重新进行定义，赋予其另一种功能，以适应不同的数据类型

加法运算符重载

1.通过成员函数重载“+” 2.通过全局函数重载“+”

#include <iostream> using namespace std; class Person { public: int m_a; int m_b; Person(int a,int b) { this->m_a=a; this->m_b=b; } Person(){} // 1.通过成员函数重载“+” 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; } }; // 2.通过全局函数重载“+” //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; //} void func1() { Person p1(10,10); Person p2(10,10); Person p3=p1+p2; cout<<p3.m_a<<" "<<p3.m_b<<endl; } int main() { func1(); return 0; } 左移运算符重载 通过全局函数重载“<<” #include <iostream> #include <ostream> using namespace std; class Person { public: int m_a; int m_b; }; ostream& operator<<(ostream &cout,Person p) //返回输出流对象 { cout<<p.m_a<<" "<<p.m_b; return cout; //链式编程思想 } void func() { Person p; p.m_a=10; p.m_b=10; cout<<p<<endl; } int main() { func(); return 0; } 递增运算符重载 1.重置前置++运算符 2.重置后置++运算符 #include <iostream> #include <ostream> using namespace std; class MyInteger { friend ostream& operator<<(ostream &cout,MyInteger myInteger); public: MyInteger(){m_Num=0;} MyInteger& operator++() //前置递增重载函数 { m_Num++; return *this; } MyInteger operator++(int) //int 代表占位参数，用于区分前置和后置 { MyInteger temp=*this; m_Num++; //递增后返回原数 return temp; //返回的是局部变量 注意返回值而不是引用！ } private: int m_Num; }; ostream& operator<<(ostream &cout,MyInteger myInteger) { cout<<myInteger.m_Num; return cout; } void test01() { MyInteger myInteger; cout<<myInteger<<endl; cout<<++myInteger<<endl; //前置递增 cout<<myInteger++<<endl; //后置递增 cout<<myInteger<<endl; } int main() { test01(); return 0; }

赋值运算符重载 #include <iostream> using namespace std; class Person { public: int *m_Age; Person(int age) { m_Age=new int(age); } ~Person() { if(m_Age!=NULL) { delete m_Age; m_Age=NULL; } } Person& operator=(Person &p) { if(m_Age!=NULL) //判断是否函数堆区内存 { delete m_Age; m_Age=NULL; } m_Age=new int(*p.m_Age); //深拷贝 return *this; //链式编程 } }; void test01() { Person p1(18); Person p2(20); Person p3(22); p3=p2=p1; cout<<*p1.m_Age<<endl; cout<<*p2.m_Age<<endl; cout<<*p3.m_Age<<endl; } int main() { test01(); return 0; } 关系运算符重载 重载关系运算符“==”， “>” #include <iostream> #include <string> using namespace std; class Person { public: int m_Age; string m_Name; Person(string name,int age) { this->m_Age=age; this->m_Name=name; } bool operator==(Person &p) { if(this->m_Age==p.m_Age) return true; else return false; } bool operator>(Person &p) { if(this->m_Age>p.m_Age) return true; else return false; } }; void test01() { Person p1("A",18); Person p2("B",18); Person p3("C",20); if(p1==p2) cout<<"same age"<<endl; else cout<<"different age"<<endl; if(p1>p2) cout<<"bigger age"<<endl; else cout<<"small age"<<endl; } int main() { test01(); 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，因此称之为仿函数 仿函数没有固定写法，非常灵活 #include <iostream> #include <string> using namespace std; class MyPrint { public: void operator()(string test) //重载函数调用运算符 { cout<<test<<endl; } }; class MyAdd { public: int operator()(int a,int b) { return a+b; } }; void test01() { MyPrint myPrint; myPrint("USTC_ZS"); //仿函数 } void test02() { MyAdd myAdd; int result=myAdd(100,200); cout<<result<<endl; //匿名函数对象 cout<<MyAdd()(100,100)<<endl; } int main() { test01(); test02(); return 0; }