它是一个法律符号：Foo& foo = Bar; [英] Is it a legal notation: Foo &foo = Bar;

问题描述

  struct Foo {}; 
 struct Bar：Foo {}; 
 
 Foo& foo = Bar; // without（）
  

我不知道，这是一个法律符号吗？如果是合法的，你能给一些细节吗？有什么，为什么是合法的？或者，这样的符号的起源是什么？

编辑：我无法编译此代码。但我遇到了一个像这样的代码，想知道是否允许这样的符号（可能只是我的编译器不支持这种符号）。我有一些不确定性，因为下面的符号是合法的： Foo * pFoo = new Bar;

解决方案

1. 不能为引用/对象分配类名。



2. 您不能绑定对临时（rvalue）的引用，因此以下内容也是非法的：

   
   
   

   Foo& foo = Bar（）;




3. 可以将一个临时（rvalue）绑定到一个const引用，所以以下是合法的：

   
   
   

   const Foo& foo = Bar code>




C ++标准特别允许3。

struct Foo {};
struct Bar : Foo {};

Foo &foo = Bar; // without ()

I wonder, Is it a legal notation? And if it is legal, could you give some details? Something like, Why it's legal? Or, What is the origin of such a notation?

EDIT: I cannot compile this code. But I met a code like that and wanted to know whether such a notation is allowed (probably just my compiler doesn't support this notation). I'm having some uncertainty since the following notation is quite legal: Foo *pFoo = new Bar;

解决方案

1. You cannot assign an class Name to a reference/object. It is neither syntactically valid nor does it make any sense.

2. You cannot bind a reference to a temporary(rvalue), So following is illegal too:

   Foo &foo = Bar();

3. You can bind a temporary(rvalue) to an const reference, So following is legal:

   const Foo &foo = Bar();

The C++ standard specifically allows the 3.

这篇关于它是一个法律符号：Foo& foo = Bar;的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！