带有 const 参数和重载的函数 [英] Functions with const arguments and Overloading

问题描述

正在试用 stackeroverflow qn 所以它让我思考为什么不重载该函数，我想出了一个稍微不同的代码，但它说该函数不能被重载.我的问题是为什么?或者有其他方法吗?

Was tryin out the stackeroverflow qn so it got me thinking why not overload the the function and I came up with a slightly different code but it says the function cannot be overloaded. My question is why? or is there a another way?

 #include <iostream>
 using std::cout;

 class Test {
         public:
         Test(){ }
         int foo (const int) const;
         int foo (int );
 };

 int main ()
 {
         Test obj;
         Test const obj1;
         int variable=0;
     do{
         obj.foo(3);        // Call the const function 
          obj.foo(variable); // Want to make it call the non const function 
         variable++;
             usleep (2000000);
        }while(1);
 }

 int Test::foo(int a)
 {
    cout<<"NON CONST"<<std::endl;
    a++;
    return a;
 }

 int Test::foo (const int a) const
 {
    cout<<"CONST"<<std::endl;
    return a;
 }

推荐答案

不能仅基于非指针、非引用类型的常量性进行重载.

You can't overload based only on the constness of a non pointer, non reference type.

想想如果你是编译器.面对线:

Think for instance if you were the compiler. Faced with the line:

 cout <<obj.foo(3);

你会调用哪个函数?

当您按值传递时，值会以任何方式复制.参数上的 const 仅与函数定义相关.

As you are passing by value the value gets copied either way. The const on the argument is only relevant to the function definition.

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