C++const和operator关键字

const 类

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class Test{
    public:
  int value = 1;
    void getvalue() const{
       // this->value = 2;//wrong,常成员函数不可修改成员变量
    }
    void setvalue(){
        this->value = 2;//true
    }
};
void test(){
    const Test name;
    //name.value = 10;//wrong,不可修改
   // Cannot assign to variable 'name' with const-qualified type 'const Test'
   // name.setvalue();//wrong常量类不可执行非常量函数
    //'this' argument to member function 'setvalue' has type 'const Test', but function is not marked const
    name.getvalue();//ture
}

在类中定义下面类型算重载不算重复定义

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class Test{
  void test(){
      
  }  
    void test()const{
        
    }
};

operator关键字

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class OverLoad{
public:
    int value = 0;
    int num = 0;
    OverLoad(){ }
    OverLoad(int value,int num = 0){
        this->value = value;
        this->num = num;
    }
    OverLoad operator +(const OverLoad&a){
        this->value += a.value;
        this->num += a.num;
        return OverLoad(this->value,this->num);
    }//重载为成员函数时操作数比操作符数量少1.
    void get_value()const{
        cout<<"the value is "<<this->value<<endl;
    }

};
//OverLoad operator + (const OverLoad &a, const OverLoad &b){
//    return OverLoad(a.value+b.value, a.num+b.num);
//}//重载为普通函数时操作数等于操作符数量
void OverLoadTest(){
    OverLoad a(10,5),b(20,5);
    OverLoad c;
    c = a + b;
    c.get_value();
}