C++ : 类类名 :: 引用 { ... }

发布于 2024-12-12 08:31:32 字数 841 浏览 0 评论 0原文

我正在学习 stl，从未见过像 class classname :: reference {} 这样的类，

我在网上搜索但可以获得很好的信息..

class bitset::reference {
  friend class bitset;
  reference();                                 // no public constructor
public:
  ~reference();
  operator bool () const;                      // convert to bool
  reference& operator= ( bool x );             // assign from bool
  reference& operator= ( const reference& x ); // assign from bit
  reference& flip();                           // flip bit value
  bool operator~() const;                      // return inverse value
};

这里的 :: reference 是做什么用的？

我在这里看到了这段代码[在此处输入链接描述][1] http://www.cplusplus.com/reference/stl/bitset/ 我以前从事过c++工作。

原文

I was learning stl and never saw this kind of class like class classname :: reference {}

I searched on the net but could get good information ..

class bitset::reference {
  friend class bitset;
  reference();                                 // no public constructor
public:
  ~reference();
  operator bool () const;                      // convert to bool
  reference& operator= ( bool x );             // assign from bool
  reference& operator= ( const reference& x ); // assign from bit
  reference& flip();                           // flip bit value
  bool operator~() const;                      // return inverse value
};

what is this :: reference here for ?

i saw this code here[enter link description here][1]
http://www.cplusplus.com/reference/stl/bitset/
i have worked on c++ before.

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莫言歌 2024-12-19 08:31:32

您查看了 bitset 类定义吗？某处有这样的事情：

template<size_t _Bits>
class bitset
{
    ...
    class reference;
    ...
}

这很像将函数的主体放在类主体之外。现在我们将嵌套类的主体放在父类之外：

class bitset::reference
{
    /* class body */
}

顺便说一下，在 MSVC (C:\Program Files\Microsoft Visual Studio 9.0\VC\include\bitset) 中，有实际上是在彼此内部定义的：

// TEMPLATE CLASS bitset
template<size_t _Bits>
class bitset
{   // store fixed-length sequence of Boolean elements
typedef unsigned long _Ty;  // base type for a storage word
enum {digits = _Bits};  // extension: compile-time size()

public:
typedef bool element_type;  // retained

    // CLASS reference
class reference
    {   // proxy for an element
    friend class bitset<_Bits>;
    .
    .
    .

与 g++ 的 bitset.h 相同，尽管稍微复杂一些。

Did you look at the bitset class definition? There is something like this somewhere:

template<size_t _Bits>
class bitset
{
    ...
    class reference;
    ...
}

It's much like putting the body of a funciton outside the class body. Now we are putting the body of a nested class outside of the parent class:

class bitset::reference
{
    /* class body */
}

By the way, in MSVC (C:\Program Files\Microsoft Visual Studio 9.0\VC\include\bitset) the're actually defined inside each other:

// TEMPLATE CLASS bitset
template<size_t _Bits>
class bitset
{   // store fixed-length sequence of Boolean elements
typedef unsigned long _Ty;  // base type for a storage word
enum {digits = _Bits};  // extension: compile-time size()

public:
typedef bool element_type;  // retained

    // CLASS reference
class reference
    {   // proxy for an element
    friend class bitset<_Bits>;
    .
    .
    .

It's the same for g++'s bitset.h, although a bit more complex.

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