C/C++编程：流的基类std::basic_ios

Myth丶恋晨 2022-05-18 05:40 222阅读 0赞

>     template <class charT, class traits = char_traits<charT> >
>       class basic_ios;
> 
> **流的基类（与类型有关的组件）：**管理任意流缓冲
> 
> ![20210303201338634.png][]
> 
> ![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3poaXpoZW5nZ3Vhbg_size_16_color_FFFFFF_t_70][]
> 
> 模板类，用于实例化所有流类的基类
> 
> 类模板在它继承的ios\_base组件中添加了以下信息:
> 
> <table> 
>  <tbody> 
>   <tr> 
>    <td>&nbsp;</td> 
>    <td>field</td> 
>    <td>成员函数</td> 
>    <td>描述</td> 
>   </tr> 
>   <tr> 
>    <td><em>状态</em></td> 
>    <td>填充字符</td> 
>    <td><a href="http://www.cplusplus.com/basic_ios::fill" rel="nofollow">fill</a></td> 
>    <td>字符填充格式的字段，直到&nbsp;<em>field width</em>&nbsp;(<a href="http://www.cplusplus.com/ios_base::width" rel="nofollow">width</a>).</td> 
>   </tr> 
>   <tr> 
>    <td><em>状态</em></td> 
>    <td>错误状态</td> 
>    <td><a href="http://www.cplusplus.com/basic_ios::rdstate" rel="nofollow">rdstate</a><br><a href="http://www.cplusplus.com/basic_ios::setstate" rel="nofollow">setstate</a><br><a href="http://www.cplusplus.com/basic_ios::clear" rel="nofollow">clear</a></td> 
>    <td>流的当前错误状态<br> 单个值可以通过调用&nbsp;<a href="http://www.cplusplus.com/basic_ios::good" rel="nofollow">good</a>,&nbsp;<a href="http://www.cplusplus.com/basic_ios::eof" rel="nofollow">eof</a>,&nbsp;<a href="http://www.cplusplus.com/basic_ios::fail" rel="nofollow">fail</a>&nbsp;和<a href="http://www.cplusplus.com/basic_ios::bad" rel="nofollow">bad</a>.来获得。<br> 具体见 成员类型&nbsp;<a href="http://www.cplusplus.com/ios_base::iostate" rel="nofollow">iostate</a>.</td> 
>   </tr> 
>   <tr> 
>    <td>异常掩码</td> 
>    <td><a href="http://www.cplusplus.com/basic_ios::exceptions" rel="nofollow">exceptions</a></td> 
>    <td>引发&nbsp;<a href="http://www.cplusplus.com/ios_base::failure" rel="nofollow">failure</a>&nbsp;异常的状态标志<br> 具体见 成员类型&nbsp;<a href="http://www.cplusplus.com/ios_base::iostate" rel="nofollow">iostate</a>.</td> 
>   </tr> 
>   <tr> 
>    <td><em>Other</em></td> 
>    <td>tied stream</td> 
>    <td><a href="http://www.cplusplus.com/basic_ios::tie" rel="nofollow">tie</a></td> 
>    <td>指向输出流的指针，该输出流在对该流的每个I / O操作之前已刷新</td> 
>   </tr> 
>   <tr> 
>    <td>流缓冲区</td> 
>    <td><a href="http://www.cplusplus.com/basic_ios::rdbuf" rel="nofollow">rdbuf</a></td> 
>    <td>指向关联的指针&nbsp;<a href="http://www.cplusplus.com/basic_streambuf" rel="nofollow">basic_streambuf</a>&nbsp;对象，负责所有输入/输出操作。</td> 
>   </tr> 
>  </tbody> 
> </table>
> 
> **模板参数**
> 
> <table style="width:500px;"> 
>  <tbody> 
>   <tr> 
>    <td>charT</td> 
>    <td>字符类型</td> 
>   </tr> 
>   <tr> 
>    <td>traits</td> 
>    <td><a href="http://www.cplusplus.com/char_traits" rel="nofollow">字符特征</a>类，它定义流对象使用的字符的基本属性（请参阅<a href="http://www.cplusplus.com/char_traits" rel="nofollow">char_traits</a>）</td> 
>   </tr> 
>  </tbody> 
> </table>

# 模板实例化 #

> <table style="width:500px;"> 
>  <tbody> 
>   <tr> 
>    <td> <p><a href="http://www.cplusplus.com/reference/ios/ios/" rel="nofollow"><strong>ios</strong></a></p> </td> 
>    <td>流的基类（与类型有关的组件）<span style="color:#008000;">（类）</span></td> 
>   </tr> 
>   <tr> 
>    <td> <p><a href="http://www.cplusplus.com/reference/ios/wios/" rel="nofollow"><strong>wios</strong></a></p> </td> 
>    <td>宽字符流的基类<span style="color:#008000;">（类）</span></td> 
>   </tr> 
>  </tbody> 
> </table>
> 
> 这些实例化在[<iosfwd>][iosfwd]中声明 ，通过引用将其包含在 [<ios>][ios] 和 [<iostream>][iostream]

# 成员类型 #

> <table style="width:500px;"> 
>  <thead> 
>   <tr> 
>    <th>成员类型</th> 
>    <th>描述</th> 
>    <th>note</th> 
>   </tr> 
>  </thead> 
>  <tbody> 
>   <tr> 
>    <td>char_type</td> 
>    <td>第一个模板参数(charT)</td> 
>    <td>&nbsp;</td> 
>   </tr> 
>   <tr> 
>    <td>traits_type</td> 
>    <td>&nbsp;第二个模板参数(traits)</td> 
>    <td>默认<a href="http://www.cplusplus.com/char_traits" rel="nofollow">char_traits</a>&lt;charT&gt;</td> 
>   </tr> 
>   <tr> 
>    <td>int_type</td> 
>    <td><a href="http://www.cplusplus.com/char_traits" rel="nofollow">traits_type</a>::int_type</td> 
>    <td>&nbsp;</td> 
>   </tr> 
>   <tr> 
>    <td>pos_type</td> 
>    <td><a href="http://www.cplusplus.com/char_traits" rel="nofollow">traits_type</a>::pos_type</td> 
>    <td>一般来说，与&nbsp;<a href="http://www.cplusplus.com/streampos" rel="nofollow">streampos</a>相同</td> 
>   </tr> 
>   <tr> 
>    <td>off_type</td> 
>    <td><a href="http://www.cplusplus.com/char_traits" rel="nofollow">traits_type</a>::off_type</td> 
>    <td>一般来说，与&nbsp;&nbsp;<a href="http://www.cplusplus.com/streamoff" rel="nofollow">streamoff</a>相同</td> 
>   </tr> 
>  </tbody> 
> </table>
> 
> 以及从[ios\_base][ios_base]继承的成员类型 ：
> 
> <table style="width:500px;"> 
>  <tbody> 
>   <tr> 
>    <td> <p><a href="http://www.cplusplus.com/reference/ios/ios_base/event/" rel="nofollow"><strong>event</strong></a></p> </td> 
>    <td>表示事件类型的类型<span style="color:#008000;">（公共成员类型）</span></td> 
>   </tr> 
>   <tr> 
>    <td> <p><a href="http://www.cplusplus.com/reference/ios/ios_base/event_callback/" rel="nofollow"><strong>event_callback</strong></a></p> </td> 
>    <td>事件回调函数类型<span style="color:#008000;">（公共成员类型）</span></td> 
>   </tr> 
>   <tr> 
>    <td> <p><a href="http://www.cplusplus.com/reference/ios/ios_base/failure/" rel="nofollow"><strong>failure</strong></a></p> </td> 
>    <td>流异常的基类<span style="color:#008000;">（公共成员类）</span></td> 
>   </tr> 
>   <tr> 
>    <td> <p><a href="http://www.cplusplus.com/reference/ios/ios_base/fmtflags/" rel="nofollow"><strong>fmtflags</strong></a></p> </td> 
>    <td>流格式标志的<span style="color:#008000;">类型（公共成员类型）</span></td> 
>   </tr> 
>   <tr> 
>    <td> <p><a href="http://www.cplusplus.com/reference/ios/ios_base/Init/" rel="nofollow"><strong>Init</strong></a></p> </td> 
>    <td>初始化标准流对象<span style="color:#008000;">（公共成员类）</span></td> 
>   </tr> 
>   <tr> 
>    <td> <p><a href="http://www.cplusplus.com/reference/ios/ios_base/iostate/" rel="nofollow"><strong>iostate</strong></a></p> </td> 
>    <td>流状态标志的<span style="color:#008000;">类型（公共成员类型）</span></td> 
>   </tr> 
>   <tr> 
>    <td> <p><a href="http://www.cplusplus.com/reference/ios/ios_base/openmode/" rel="nofollow"><strong>openmode</strong></a></p> </td> 
>    <td>流打开模式标志的<span style="color:#008000;">类型（公共成员类型）</span></td> 
>   </tr> 
>   <tr> 
>    <td> <p><a href="http://www.cplusplus.com/reference/ios/ios_base/seekdir/" rel="nofollow"><strong>seekdir</strong></a></p> </td> 
>    <td>流搜索方向标志的<span style="color:#008000;">类型（公共成员类型）</span></td> 
>   </tr> 
>  </tbody> 
> </table>
> 
> \--

# 公共成员函数 #

<table style="width:500px;"> 
 <tbody> 
  <tr> 
   <td> <p><a href="http://www.cplusplus.com/reference/ios/basic_ios/basic_ios/" rel="nofollow"><strong>(constructor)</strong></a></p> </td> 
   <td>构造对象<span style="color:#008000;">（公共成员函数）</span></td> 
  </tr> 
  <tr> 
   <td> <p><a href="http://www.cplusplus.com/reference/ios/basic_ios/~basic_ios/" rel="nofollow"><strong>(destructor)</strong></a></p> </td> 
   <td>销毁对象<span style="color:#008000;">（公共成员函数）</span></td> 
  </tr> 
 </tbody> 
</table>

## 构造函数 ##

> <table> 
>  <tbody> 
>   <tr> 
>    <td style="width:129px;">intialization (1)&nbsp;&nbsp; &nbsp;</td> 
>    <td style="width:611px;"> <pre><code>public: explicit basic_ios (basic_streambuf&lt;char_type,traits_type&gt;* sb);</code></pre> </td> 
>   </tr> 
>   <tr> 
>    <td style="width:129px;">default (2)</td> 
>    <td style="width:611px;">protected: basic_ios();</td> 
>   </tr> 
>   <tr> 
>    <td style="width:129px;"><em>copy（3）</em></td> 
>    <td style="width:611px;">basic_ios (const basic_ios&amp;) = delete;<br> basic_ios&amp; operator= (const basic_ios&amp;) = delete;</td> 
>   </tr> 
>  </tbody> 
> </table>
> 
> **构造新的 `basic_ios` 对象**
> 
> 1) 以调用init(sb) 初始化内部状态。设置关联流缓冲为 `sb` 。
> 
> 2）默认构造函数。不初始化内部状态。必须在首次使用对象或析构函数前调用 [init()][init] ，否则行为未定义
> 
> 3）复制、拷贝构造函数被删除

<table style="width:500px;">  状态函数  
 <tbody> 
  <tr> 
   <td><a href="https://zh.cppreference.com/w/cpp/io/basic_ios/good" rel="nofollow">good</a></td> 
   <td>检查是否没有发生错误</td> 
  </tr> 
  <tr> 
   <td> <p><a href="http://www.cplusplus.com/reference/ios/basic_ios/eof/" rel="nofollow"><strong>eof</strong></a></p> </td> 
   <td>检查是否到达了文件末尾</td> 
  </tr> 
  <tr> 
   <td> <p><a href="http://www.cplusplus.com/reference/ios/basic_ios/fail/" rel="nofollow"><strong>fail</strong></a></p> </td> 
   <td>检查是否发生了可恢复的错误</td> 
  </tr> 
  <tr> 
   <td> <p><a href="http://www.cplusplus.com/reference/ios/basic_ios/bad/" rel="nofollow"><strong>bad</strong></a></p> </td> 
   <td>检查是否已发生不可恢复的错误</td> 
  </tr> 
  <tr> 
   <td> <p><a href="http://www.cplusplus.com/reference/ios/basic_ios/operator_not/" rel="nofollow"><strong>operator!</strong></a></p> </td> 
   <td>检查是否有错误发生（<a href="https://zh.cppreference.com/w/cpp/io/basic_ios/fail" rel="nofollow">fail()</a>&nbsp;的同义词）</td> 
  </tr> 
  <tr> 
   <td> <p><a href="http://www.cplusplus.com/reference/ios/basic_ios/operator_bool/" rel="nofollow"><strong>operator bool&nbsp;</strong></a></p> </td> 
   <td>检查是否没有发生错误（!fail()的同义词）</td> 
  </tr> 
  <tr> 
   <td> <p><a href="http://www.cplusplus.com/reference/ios/basic_ios/rdstate/" rel="nofollow"><strong>rdstate</strong></a></p> </td> 
   <td>返回状态标志</td> 
  </tr> 
  <tr> 
   <td> <p><a href="http://www.cplusplus.com/reference/ios/basic_ios/setstate/" rel="nofollow"><strong>setstate</strong></a></p> </td> 
   <td>设置状态标志</td> 
  </tr> 
  <tr> 
   <td> <p><a href="http://www.cplusplus.com/reference/ios/basic_ios/clear/" rel="nofollow"><strong>clear</strong></a></p> </td> 
   <td>修改状态标志</td> 
  </tr> 
 </tbody> 
</table>

## std::[basic\_ios][basic_ios]::good、std::basic\_ios::bad、std::basic\_ios::fail ##

>     bool good() const;
> 
> 若流未出现错误（最近 I/O 操作成功完成）则为 true ，否则为 false
> 
>     bool bad() const;
> 
> 若关联的流上已出现**不可恢复的错误**则返回 true 。尤其是若 rdstate() 中设置了 [badbit][] 则返回 true 。
> 
> 设置 `badbit` 的条件列表见 [ios\_base::iostate][badbit]
> 
>     bool fail() const;
> 
> 若关联流上已发生(可恢复的)错误则返回 true 。特别是若 [rdstate()][rdstate] 中设置了 `badbit` 或 `failbit` 则返回 true 。
> 
> 设置 `failbit` 或 `badbit` 的条件列表见 [ios\_base::iostate][badbit] 。

> 下表显示 `basic_ios` 访问器（ **good()**、 [fail()][fail] 等）对于 [ios\_base::iostate][badbit] 标志的所有可能组合的值：
> 
> <table> 
>  <tbody> 
>   <tr> 
>    <td colspan="3"><a href="https://zh.cppreference.com/w/cpp/io/ios_base/iostate" rel="nofollow">ios_base::iostate</a>&nbsp;标志</td> 
>    <td colspan="6"><code>basic_ios</code>&nbsp;访问器</td> 
>   </tr> 
>   <tr> 
>    <td>eofbit</td> 
>    <td>failbit</td> 
>    <td>badbit</td> 
>    <td><strong>good()</strong></td> 
>    <td><a href="https://zh.cppreference.com/w/cpp/io/basic_ios/fail" rel="nofollow">fail()</a></td> 
>    <td><a href="https://zh.cppreference.com/w/cpp/io/basic_ios/bad" rel="nofollow">bad()</a></td> 
>    <td><a href="https://zh.cppreference.com/w/cpp/io/basic_ios/eof" rel="nofollow">eof()</a></td> 
>    <td><a href="https://zh.cppreference.com/w/cpp/io/basic_ios/operator_bool" rel="nofollow">operator bool</a></td> 
>    <td><a href="https://zh.cppreference.com/w/cpp/io/basic_ios/operator!" rel="nofollow">operator!</a></td> 
>   </tr> 
>   <tr> 
>    <td>false</td> 
>    <td>false</td> 
>    <td>false</td> 
>    <td>true</td> 
>    <td>false</td> 
>    <td>false</td> 
>    <td>false</td> 
>    <td>true</td> 
>    <td>false</td> 
>   </tr> 
>   <tr> 
>    <td>false</td> 
>    <td>false</td> 
>    <td>true</td> 
>    <td>false</td> 
>    <td>true</td> 
>    <td>true</td> 
>    <td>false</td> 
>    <td>false</td> 
>    <td>true</td> 
>   </tr> 
>   <tr> 
>    <td>false</td> 
>    <td>true</td> 
>    <td>false</td> 
>    <td>false</td> 
>    <td>true</td> 
>    <td>false</td> 
>    <td>false</td> 
>    <td>false</td> 
>    <td>true</td> 
>   </tr> 
>   <tr> 
>    <td>false</td> 
>    <td>true</td> 
>    <td>true</td> 
>    <td>false</td> 
>    <td>true</td> 
>    <td>true</td> 
>    <td>false</td> 
>    <td>false</td> 
>    <td>true</td> 
>   </tr> 
>   <tr> 
>    <td>true</td> 
>    <td>false</td> 
>    <td>false</td> 
>    <td>false</td> 
>    <td>false</td> 
>    <td>false</td> 
>    <td>true</td> 
>    <td>true</td> 
>    <td>false</td> 
>   </tr> 
>   <tr> 
>    <td>true</td> 
>    <td>false</td> 
>    <td>true</td> 
>    <td>false</td> 
>    <td>true</td> 
>    <td>true</td> 
>    <td>true</td> 
>    <td>false</td> 
>    <td>true</td> 
>   </tr> 
>   <tr> 
>    <td>true</td> 
>    <td>true</td> 
>    <td>false</td> 
>    <td>false</td> 
>    <td>true</td> 
>    <td>false</td> 
>    <td>true</td> 
>    <td>false</td> 
>    <td>true</td> 
>   </tr> 
>   <tr> 
>    <td>true</td> 
>    <td>true</td> 
>    <td>true</td> 
>    <td>false</td> 
>    <td>true</td> 
>    <td>true</td> 
>    <td>true</td> 
>    <td>false</td> 
>    <td>true</td> 
>   </tr> 
>  </tbody> 
> </table>
> 
> \--

// error state flags
    #include <iostream>     // std::cout, std::ios
    #include <sstream>      // std::stringstream
    
    void print_state (const std::ios& stream) {
      std::cout << " good()=" << stream.good();
      std::cout << " eof()=" << stream.eof();
      std::cout << " fail()=" << stream.fail();
      std::cout << " bad()=" << stream.bad();
    }
    
    int main () {
      std::stringstream stream;
    
      stream.clear (stream.goodbit);
      std::cout << "goodbit:"; print_state(stream); std::cout << '\n';
    
      stream.clear (stream.eofbit);
      std::cout << " eofbit:"; print_state(stream); std::cout << '\n';
    
      stream.clear (stream.failbit);
      std::cout << "failbit:"; print_state(stream); std::cout << '\n';
    
      stream.clear (stream.badbit);
      std::cout << " badbit:"; print_state(stream); std::cout << '\n';
    
      return 0;
    }

![20210303205129953.png][]

## std::[basic\_ios][basic_ios]::eof ##

>     bool eof（）const;
> 
> 检查当前 [rdstate()][rdstate] 是否设置了eofbit：
> 
>  *  当按与流关联的顺序到达文件结束时，所有标准输入操作都会设置此标志。
>  *  也就是说**检查是否到达了文件末尾**
>  *  具体设置 `eofbit` 的条件列表见 [ios\_base::iostate][badbit] 。  
>     \-

// ios::eof example
    #include <iostream>     // std::cout
    #include <fstream>      // std::ifstream
    
    int main () {
    
      std::ifstream is("example.txt");   // open file
    
      char c;
      while (is.get(c))                  // loop getting single characters
        std::cout << c;
    
      if (is.eof())                      // check for EOF
        std::cout << "[EoF reached]\n";
      else
        std::cout << "[error reading]\n";
    
      is.close();                        // close file
    
      return 0;
    }

## std :: [basic\_ios][basic_ios] :: operator！ ##

>     bool operator!() const;
> 
> 检查是否有错误发生
> 
>  *  若关联流上已出现错误则返回 true 。特别是若 rdstate() 中设置了 `failbit` 或 `badbit` 则返回 true
>  *  [fail()][fail] 的同义词

#include <iostream>
    #include <fstream>
    #include <cstdlib>
    int main()
    {
        std::ifstream file("test.txt");
        if(!file)  // operator! 用于此
        {  
            std::cout << "File opening failed\n";
            return EXIT_FAILURE;
        }
     
        // 典型的 C++ I/O 循环以 I/O 函数的返回值为循环控制条件，
        // operator bool() 用于此
        for(int n; file >> n; ) {
           std::cout << n << ' ';
        }
        std::cout << '\n';
     
        if (file.bad())
            std::cout << "I/O error while reading\n";
        else if (file.eof())
            std::cout << "End of file reached successfully\n";
        else if (file.fail())
            std::cout << "Non-integer data encountered\n";
    }

## std::[basic\_ios][basic_ios]::operator bool ##

>     explicit operator bool() const;
> 
> 检查是否没有发生错误
> 
>  *  若流无错误且已为 I/O 操作就绪则返回 true
>  *  !fail()的同义词

// evaluating a stream
    #include <iostream>     // std::cerr
    #include <fstream>      // std::ifstream
    
    int main () {
      std::ifstream is;
      is.open ("test.txt");
      if (is) {
        // read file
      }
      else {
        std::cerr << "Error opening 'test.txt'\n";
      }
      return 0;
    }

#include <iostream>
    #include <sstream>
     
    int main()
    {
        std::istringstream s("1 2 3 error");
        int n;
        std::cout << std::boolalpha << "s is " << static_cast<bool>(s) << '\n';
        while (s >> n) {
            std::cout << n << '\n';
        }
        std::cout << "s is " << static_cast<bool>(s) << '\n';
    }

![20210303210525912.png][]

## std :: [basic\_ios][basic_ios] :: rdstate ##

>     iostate rdstate() const;
> 
> 返回当前错误状态
> 
> ### 返回值 ###
> 
> 当前错误状态。它是位掩码类型，并且能是下列常量的组合：
> 
> <table> 
>  <tbody> 
>   <tr> 
>    <td>常量</td> 
>    <td>解释</td> 
>   </tr> 
>   <tr> 
>    <td><a href="https://zh.cppreference.com/w/cpp/io/ios_base/iostate" rel="nofollow">goodbit</a></td> 
>    <td>无错误</td> 
>   </tr> 
>   <tr> 
>    <td><a href="https://zh.cppreference.com/w/cpp/io/ios_base/iostate" rel="nofollow">badbit</a></td> 
>    <td>不可恢复的流错误</td> 
>   </tr> 
>   <tr> 
>    <td><a href="https://zh.cppreference.com/w/cpp/io/ios_base/iostate" rel="nofollow">failbit</a></td> 
>    <td>输入/输出操作失败（格式化或提取错误）</td> 
>   </tr> 
>   <tr> 
>    <td><a href="https://zh.cppreference.com/w/cpp/io/ios_base/iostate" rel="nofollow">eofbit</a></td> 
>    <td>关联的输出序列已抵达文件尾</td> 
>   </tr> 
>  </tbody> 
> </table>
> 
> ### \- ###

// getting the state of stream objects
    #include <iostream>     // std::cerr
    #include <fstream>      // std::ifstream
    
    int main () {
      std::ifstream is;
      is.open ("test.txt");
      if ( (is.rdstate() & std::ifstream::failbit ) != 0 )
        std::cerr << "Error opening 'test.txt'\n";
      return 0;
    }

#include <iostream>
    #include <sstream>
     
    int main()
    {
      std::ostringstream stream;
     
      if (stream.rdstate() == std::ios_base::goodbit) {
        std::cout << "stream state is goodbit\n";
      }
     
      stream.setstate(std::ios_base::eofbit);
     
      // 检查状态为准确的 eofbit （无 failbit 且无 badbit ）
      if (stream.rdstate() == std::ios_base::eofbit) {
        std::cout << "stream state is eofbit\n";
      }
    }

![20210303210943782.png][]

## std::[basic\_ios][basic_ios]::setstate ##

>     void setstate( iostate state );
> 
> 在当前已设置表之外，**设置流错误状态标志 `state`** 。实质上调用 clear(rdstate() | state) 。可能抛出异常。
> 
> **参数**
> 
> <table> 
>  <tbody> 
>   <tr> 
>    <td>state</td> 
>    <td>要设置的流错误状态标志。能为下列常量的组合： 
>     <table> 
>      <tbody> 
>       <tr> 
>        <td>常量</td> 
>        <td>解释</td> 
>       </tr> 
>       <tr> 
>        <td><a href="https://zh.cppreference.com/w/cpp/io/ios_base/iostate" rel="nofollow">goodbit</a></td> 
>        <td>无错误</td> 
>       </tr> 
>       <tr> 
>        <td><a href="https://zh.cppreference.com/w/cpp/io/ios_base/iostate" rel="nofollow">badbit</a></td> 
>        <td>不可恢复的流错误</td> 
>       </tr> 
>       <tr> 
>        <td><a href="https://zh.cppreference.com/w/cpp/io/ios_base/iostate" rel="nofollow">failbit</a></td> 
>        <td>输入/输出操作失败（格式化或提取错误）</td> 
>       </tr> 
>       <tr> 
>        <td><a href="https://zh.cppreference.com/w/cpp/io/ios_base/iostate" rel="nofollow">eofbit</a></td> 
>        <td>关联的输出序列已抵达文件尾</td> 
>       </tr> 
>      </tbody> 
>     </table></td> 
>   </tr> 
>  </tbody> 
> </table>
> 
> **返回值**
> 
> （无）

#include <iostream>
    #include <sstream>
     
    int main()
    {
        std::ostringstream stream;
     
        if (!stream.fail()) {
            std::cout << "stream is not fail\n";
        }
     
        stream.setstate(std::ios_base::failbit);
     
        if (stream.fail()) {
            std::cout << "now stream is fail\n";
        }
     
        if (!stream.good()) {
            std::cout << "and stream is not good\n";
        }
    }

![20210303211322513.png][]

## std::[basic\_ios][basic_ios]::clear ##

>     void clear( std::ios_base::iostate state = std::ios_base::goodbit );
> 
>  *  通过以 `state` 的值赋值，设置流错误状态标志。默认赋值 [std::ios\_base::goodbit][badbit] ，它拥有的效果为清除所有错误状态标志。
>  *  若 [rdbuf()][rdbuf] 为空指针（即无关联的流缓冲），则赋值 state | badbit 。可能抛出异常
> 
> **参数**
> 
> <table> 
>  <tbody> 
>   <tr> 
>    <td>state</td> 
>    <td>要设置的流错误状态标志。能为下列常量的组合： 
>     <table> 
>      <tbody> 
>       <tr> 
>        <td>常量</td> 
>        <td>解释</td> 
>       </tr> 
>       <tr> 
>        <td><a href="https://zh.cppreference.com/w/cpp/io/ios_base/iostate" rel="nofollow">goodbit</a></td> 
>        <td>无错误</td> 
>       </tr> 
>       <tr> 
>        <td><a href="https://zh.cppreference.com/w/cpp/io/ios_base/iostate" rel="nofollow">badbit</a></td> 
>        <td>不可恢复的流错误</td> 
>       </tr> 
>       <tr> 
>        <td><a href="https://zh.cppreference.com/w/cpp/io/ios_base/iostate" rel="nofollow">failbit</a></td> 
>        <td>输入/输出操作失败（格式化或提取错误）</td> 
>       </tr> 
>       <tr> 
>        <td><a href="https://zh.cppreference.com/w/cpp/io/ios_base/iostate" rel="nofollow">eofbit</a></td> 
>        <td>关联的输出序列已抵达文件尾</td> 
>       </tr> 
>      </tbody> 
>     </table></td> 
>   </tr> 
>  </tbody> 
> </table>
> 
> **返回值**
> 
> （无）

#include <iostream>
    #include <string>
     
    int main()
    {
        double n;
        while( std::cout << "Please, enter a number\n"
               && ! (std::cin >> n) )
        {
            std::cin.clear();
            std::string line;
            std::getline(std::cin, line);
            std::cout << "I am sorry, but '" << line << "' is not a number\n";
        }
        std::cout << "Thank you for entering the number " << n << '\n';
    }

// clearing errors
    #include <iostream>     // std::cout
    #include <fstream>      // std::fstream
    
    int main () {
      char buffer [80];
      std::fstream myfile;
    
      myfile.open ("test.txt",std::fstream::in);
    
      myfile << "test";
      if (myfile.fail())
      {
        std::cout << "Error writing to test.txt\n";
        myfile.clear();
      }
    
      myfile.getline (buffer,80);
      std::cout << buffer << " successfully read from file.\n";
    
      return 0;
    }

在此示例中，`myfile`打开了输入操作，但我们对其执行了输出操作，因此`failbit`已设置。然后该示例调用清除 为了删除该标志并允许进一步的操作

<table style="width:500px;">  格式化  
 <tbody> 
  <tr> 
   <td><a href="https://zh.cppreference.com/w/cpp/io/basic_ios/copyfmt" rel="nofollow">copyfmt</a></td> 
   <td>复制格式化信息</td> 
  </tr> 
  <tr> 
   <td><a href="https://zh.cppreference.com/w/cpp/io/basic_ios/fill" rel="nofollow">fill</a></td> 
   <td>管理填充字符</td> 
  </tr> 
 </tbody> 
</table>

## std :: [basic\_ios][basic_ios] :: copyfmt ##

>     basic_ios& copyfmt(const basic_ios& other);
> 
> 若 other 与 \*this 指代同一对象，则无效果。否则复制流 `other` 的状态到 \*this 中。以下列序列进行：
> 
> 1) 传递 [erase\_event][erase_event] 为参数，调用 [register\_callback()][register_callback] 所注册的每个回调。
> 
> 2) 从 `other` 复制所有成员对象到 \*this ，除了 [rdstate()][rdstate] 、异常掩码和 [rdbuf()][rdbuf] 。特别是复制本地环境、格式化标志、数组 [std::ios\_base::iword][std_ios_base_iword] 和 [std::ios\_base::pword][std_ios_base_pword] 的内容（但不是 `iword` 和 `pword` 指针本身）、回调和 tie 的流。
> 
> 3) 传递 [copyfmt\_event][erase_event]为参数，调用 [register\_callback()][register_callback] 所注册的每个回调。
> 
> 4) 从 `other` 复制异常掩码到 \*this ，如同通过调用 exceptions(other.exceptions())

// copying formatting information
    #include <iostream>     // std::cout
    #include <fstream>      // std::ofstream
    
    int main () {
      std::ofstream filestr;
      filestr.open ("test.txt");
    
      std::cout.fill ('*');
      std::cout.width (10);
      filestr.copyfmt (std::cout);
    
      std::cout << 40;
      filestr << 40;
    
      return 0;
    }

本示例向两者输出以相同方式格式化的数字 [out][]还有一个文件`"test.txt"`：

![20210303212354195.png][]

## std::[basic\_ios][basic_ios]::fill ##

> <table> 
>  <tbody> 
>   <tr> 
>    <th>get (1)</th> 
>    <td>CharT fill()&nbsp;const;</td> 
>   </tr> 
>   <tr> 
>    <th>set (2)</th> 
>    <td>CharT fill(&nbsp;CharT ch&nbsp;);</td> 
>   </tr> 
>  </tbody> 
> </table>
> 
> 管理用于填充输入转换到指定宽度的填充字符。
> 
>  *  1) 返回当前的填充字符
>  *  2) 设置填充字符为 `ch` ，返回填充字符的先前值
> 
> **返回值**
> 
> 调用函数前的填充字符
> 
> 还可以用setfill 达到同样的效果

#include <iostream>
    #include <iomanip>
     
    int main ()
    {
      std::cout << "With default setting : " << std::setw(10) << 40 << '\n';
      char prev = std::cout.fill('x');
      std::cout << "Replaced '" << prev << "' with '"
                << std::cout.fill() << "': " << std::setw(10) << 40 << '\n';
    }

![2021030321281745.png][]

<table style="width:500px;">  杂项  
 <tbody> 
  <tr> 
   <td><a href="https://zh.cppreference.com/w/cpp/io/basic_ios/exceptions" rel="nofollow">exceptions</a></td> 
   <td>管理异常掩码</td> 
  </tr> 
  <tr> 
   <td><a href="https://zh.cppreference.com/w/cpp/io/basic_ios/imbue" rel="nofollow">imbue</a></td> 
   <td>设置本地环境</td> 
  </tr> 
  <tr> 
   <td><a href="https://zh.cppreference.com/w/cpp/io/basic_ios/rdbuf" rel="nofollow">rdbuf</a></td> 
   <td>管理相关的流缓冲区</td> 
  </tr> 
  <tr> 
   <td><a href="https://zh.cppreference.com/w/cpp/io/basic_ios/tie" rel="nofollow">tie</a></td> 
   <td>管理绑定的流</td> 
  </tr> 
  <tr> 
   <td><a href="https://zh.cppreference.com/w/cpp/io/basic_ios/narrow" rel="nofollow">narrow</a></td> 
   <td>窄化字符</td> 
  </tr> 
  <tr> 
   <td><a href="https://zh.cppreference.com/w/cpp/io/basic_ios/widen" rel="nofollow">widen</a></td> 
   <td>拓宽字符</td> 
  </tr> 
 </tbody> 
</table>

### std::[basic\_ios][basic_ios]::exceptions ###

> <table style="width:500px;"> 
>  <tbody> 
>   <tr> 
>    <td>get (1)</td> 
>    <td><a href="http://zh.cppreference.com/w/cpp/io/ios_base/iostate" rel="nofollow">std::ios_base::iostate</a>&nbsp;exceptions()&nbsp;const;</td> 
>   </tr> 
>   <tr> 
>    <td>set(2)</td> 
>    <td>void&nbsp;exceptions(&nbsp;<a href="http://zh.cppreference.com/w/cpp/io/ios_base/iostate" rel="nofollow">std::ios_base::iostate</a>&nbsp;except&nbsp;);</td> 
>   </tr> 
>  </tbody> 
> </table>
> 
> 获取和设置流的异常掩码。异常掩码确定在哪些错误状态出现时抛出 [failure][] 类型异常。
> 
> 1) 返回异常掩码。
> 
> 2) 设置异常掩码为 `except` 。

// basic_ios::exceptions
    #include <iostream>     // std::cerr
    #include <fstream>      // std::ifstream
    
    int main () {
      std::ifstream file;
      file.exceptions ( std::ifstream::failbit | std::ifstream::badbit );
      try {
        file.open ("test.txt");
        while (!file.eof()) file.get();
      }
      catch (std::ifstream::failure e) {
        std::cerr << "Exception opening/reading file";
      }
    
      file.close();
    
      return 0;
    }

#include <iostream>
    #include <fstream>
     
    int main() 
    {
        int ivalue;
        try {
            std::ifstream in("in.txt");
            in.exceptions(std::ifstream::failbit);
            in >> ivalue;
        } catch (std::ios_base::failure &fail) {
            // 此处处理异常
        }
    }

## std::[basic\_ios][basic_ios]::imbue ##

>     std::locale imbue( const std::locale& loc );
> 
> 替换当前本地环境。等效地调用 ios\_base::imbue(loc) ，而若有关联流缓冲（ rdbuf() != 0 ），则再调用 rdbuf()->pubimbue(loc)

#include <iostream>
    #include <sstream>
    #include <locale>
     
    int main()
    {
        std::istringstream iss;
        iss.imbue(std::locale("en_US.UTF8"));
     
        std::cout << "Current locale: " << iss.getloc().name() << '\n';
     
        iss.imbue(std::locale());
        std::cout << "Global locale : " << iss.getloc().name() << '\n';
    }

![20210303213738820.png][]

## std::[basic\_ios][basic_ios]::rdbuf ##

>     std::basic_streambuf<CharT, Traits>* rdbuf() const;              (1)	
>     std::basic_streambuf<CharT, Traits>* rdbuf( std::basic_streambuf<CharT, Traits>* sb );   (2)
> 
> 获取/设置流缓冲区
> 
>  *  1) 返回关联的流缓冲。若无关联流缓冲，则返回空指针。
>  *  2) 设置关联流缓冲为 `sb` 。通过调用 [clear()][clear] 清除错误状态。返回操作前的关联流缓冲。若无关联流缓冲，则返回空指针。

#include <iostream>
    #include <sstream>
     
    int main()
    {
        std::ostringstream local;
        auto cout_buff = std::cout.rdbuf(); // 保存指向 std::cout 缓冲的指针
     
        std::cout.rdbuf(local.rdbuf()); // 以 'local' 对象的缓冲
            // 替换内部的 std::cout 缓冲
     
        // 现在 std::cout 以 'local' 缓冲工作
        // 你看不到此消息
        std::cout << "some message";
     
        // 回到旧缓冲
        std::cout.rdbuf(cout_buff);
     
        // 你将看到此消息
        std::cout << "back to default buffer\n";
     
        // 打印 'local' 内容
        std::cout << "local content: " << local.str() << "\n";
    }

![20210303214025161.png][]

// redirecting cout's output thrrough its stream buffer
    #include <iostream>     // std::streambuf, std::cout
    #include <fstream>      // std::ofstream
    
    int main () {
      std::streambuf *psbuf, *backup;
      std::ofstream filestr;
      filestr.open ("test.txt");
    
      backup = std::cout.rdbuf();     // back up cout's streambuf
    
      psbuf = filestr.rdbuf();        // get file's streambuf
      std::cout.rdbuf(psbuf);         // assign streambuf to cout
    
      std::cout << "This is written to the file";
    
      std::cout.rdbuf(backup);        // restore cout's original streambuf
    
      filestr.close();
    
      return 0;
    }

## std::[basic\_ios][basic_ios]::tie ##

> <table style="width:665px;"> 
>  <tbody> 
>   <tr> 
>    <td>get (1)</td> 
>    <td style="width:602px;"> <p>std::basic_ostream&lt;CharT,Traits&gt;* tie() const;</p> </td> 
>   </tr> 
>   <tr> 
>    <td>set(2)</td> 
>    <td style="width:602px;"><a href="http://zh.cppreference.com/w/cpp/io/basic_ostream" rel="nofollow">std::basic_ostream</a>&lt;CharT,Traits&gt;*&nbsp;tie(&nbsp;<a href="http://zh.cppreference.com/w/cpp/io/basic_ostream" rel="nofollow">std::basic_ostream</a>&lt;CharT,Traits&gt;*&nbsp;str&nbsp;);</td> 
>   </tr> 
>  </tbody> 
> </table>
> 
> 默认情况下，联系标准流 `cin` 和 `cerr` 到 `cout` 。类似地，联系其宽对应版本 `wcin` 和 `wcerr` 到 `wcout`
> 
> **获取/设置绑定流**
> 
>  *（1）*返回一个指向绑定输出流的指针。
> 
>  *（2）*将对象绑定到tiestr，并返回指向调用之前绑定的流的指针（如果有）。

// redefine tied object
    #include <iostream>     // std::ostream, std::cout, std::cin
    #include <fstream>      // std::ofstream
    
    int main () {
      std::ostream *prevstr;
      std::ofstream ofs;
      ofs.open ("test.txt");
    
      std::cout << "tie example:\n";
    
      *std::cin.tie() << "This is inserted into cout";
      prevstr = std::cin.tie (&ofs);
      *std::cin.tie() << "This is inserted into the file";
      std::cin.tie (prevstr);
    
      ofs.close();
    
      return 0;
    }

## std :: [basic\_ios][basic_ios] :: narrow、std::[basic\_ios][basic_ios]::widen ##

>     char narrow( char_type c, char dfault ) const;
> 
>  *  将结果从 `char_type` 转换到 `char` 。若不能进行转换，则函数返回 `dfault` 。
>  *  等效地调用 [std::use\_facet][std_use_facet]< [std::ctype][std_ctype]<char\_type> >(getloc()).narrow(c, dfault); 。
> 
> **参数**
> 
> <table> 
>  <tbody> 
>   <tr> 
>    <td>c</td> 
>    <td>要转换的字符</td> 
>   </tr> 
>   <tr> 
>    <td>dfault</td> 
>    <td>若转化不成功则返回的字符</td> 
>   </tr> 
>  </tbody> 
> </table>
> 
> **返回值**
> 
> 转换到标准等价物再到 char 的字符。若转换失败则返回 `dfault` 。
> 
>     char_type widen (char c) const;
> 
>  *  将结果从 `char` 转换到 `char_type` 。
>  *  等效地调用[std::use\_facet][std_use_facet]< [std::ctype][std_ctype]<char\_type> >(getloc()).widen(c)。

# 受保护的成员函数 #

<table style="width:500px;"> 
 <tbody> 
  <tr> 
   <td><a href="https://zh.cppreference.com/w/cpp/io/basic_ios/init" rel="nofollow">init</a></td> 
   <td>初始化一个默认构造的<strong>std::basic_ios</strong></td> 
  </tr> 
  <tr> 
   <td> <p><a href="https://zh.cppreference.com/w/cpp/io/basic_ios/move" rel="nofollow">move</a></p> <p>(C++11)</p> </td> 
   <td>从另一&nbsp;<strong>std::basic_ios</strong>&nbsp;移动，除了&nbsp;<code>rdbuf</code></td> 
  </tr> 
  <tr> 
   <td> <p><a href="https://zh.cppreference.com/w/cpp/io/basic_ios/swap" rel="nofollow">swap</a></p> <p>(C++11)</p> </td> 
   <td>与另一&nbsp;<strong>std::basic_ios</strong>&nbsp;交换，除了&nbsp;<code>rdbuf</code></td> 
  </tr> 
  <tr> 
   <td><a href="https://zh.cppreference.com/w/cpp/io/basic_ios/set_rdbuf" rel="nofollow">set_rdbuf</a></td> 
   <td>替换&nbsp;<code>rdbuf</code>&nbsp;而不清除其错误状态</td> 
  </tr> 
 </tbody> 
</table>

## std::[basic\_ios][basic_ios]::init ##

>     protected:
>     void init( std::basic_streambuf<CharT,Traits>* sb );
> 
> 设置关联流缓冲为 `sb` 并初始化内部状态。
> 
> 后置条件如下：
> 
> <table> 
>  <tbody> 
>   <tr> 
>    <th>元素</th> 
>    <th>值</th> 
>   </tr> 
>   <tr> 
>    <td><a href="https://zh.cppreference.com/w/cpp/io/basic_ios/rdbuf" rel="nofollow">rdbuf()</a></td> 
>    <td><code>sb</code></td> 
>   </tr> 
>   <tr> 
>    <td><a href="https://zh.cppreference.com/w/cpp/io/basic_ios/tie" rel="nofollow">tie()</a></td> 
>    <td>空指针</td> 
>   </tr> 
>   <tr> 
>    <td><a href="https://zh.cppreference.com/w/cpp/io/basic_ios/rdstate" rel="nofollow">rdstate()</a></td> 
>    <td>若&nbsp;<code>sb</code>&nbsp;不是空指针, 则为&nbsp;<code>goodbit</code>&nbsp;，否则为&nbsp;<code>badbit</code></td> 
>   </tr> 
>   <tr> 
>    <td><a href="https://zh.cppreference.com/w/cpp/io/basic_ios/exceptions" rel="nofollow">exceptions()</a></td> 
>    <td><code>goodbit</code></td> 
>   </tr> 
>   <tr> 
>    <td><a href="https://zh.cppreference.com/w/cpp/io/ios_base/flags" rel="nofollow">flags()</a></td> 
>    <td>skipws&nbsp;|&nbsp;dec</td> 
>   </tr> 
>   <tr> 
>    <td><a href="https://zh.cppreference.com/w/cpp/io/ios_base/width" rel="nofollow">width()</a></td> 
>    <td>0</td> 
>   </tr> 
>   <tr> 
>    <td><a href="https://zh.cppreference.com/w/cpp/io/ios_base/precision" rel="nofollow">precision()</a></td> 
>    <td>6</td> 
>   </tr> 
>   <tr> 
>    <td><a href="https://zh.cppreference.com/w/cpp/io/basic_ios/fill" rel="nofollow">fill()</a></td> 
>    <td>widen(' ')</td> 
>   </tr> 
>   <tr> 
>    <td><a href="https://zh.cppreference.com/w/cpp/io/ios_base/getloc" rel="nofollow">getloc()</a></td> 
>    <td><a href="http://zh.cppreference.com/w/cpp/locale/locale" rel="nofollow">std::locale</a>()&nbsp;所返回的值的副本</td> 
>   </tr> 
>  </tbody> 
> </table>
> 
> 此成员函数为受保护：一旦知晓实际缓冲区类型，则它为派生流类 [std::basic\_istream][std_basic_istream] 和 [std::basic\_ostream][std_basic_ostream] 的构造函数所调用。直至调用此函数前，默认构造的 [std::basic\_ios][std_basic_ios] 每个成员函数（包括析构函数）都引发未定义行为。注意 `basic_ios` 是虚基类，从而其构造函数不为直接派生类的构造函数所调用，此乃二阶段初始化为必须的原因。
> 
> **参数**
> 
> <table> 
>  <tbody> 
>   <tr> 
>    <td>sb</td> 
>    <td>要关联到的流缓冲</td> 
>   </tr> 
>  </tbody> 
> </table>
> 
> **参阅**
> 
> <table> 
>  <tbody> 
>   <tr> 
>    <td> <p><a href="https://zh.cppreference.com/w/cpp/io/basic_ios/basic_ios" rel="nofollow">(构造函数)</a></p> </td> 
>    <td>构造对象</td> 
>   </tr> 
>  </tbody> 
> </table>
> 
> \--

# 从[ios\_base][ios_base]继承的公共成员函数 #

#  #

<table> 
 <tbody> 
  <tr> 
   <td> <p><a href="http://www.cplusplus.com/reference/ios/ios_base/flags/" rel="nofollow"><strong>flags</strong></a></p> </td> 
   <td>获取/设置格式标志（公共成员函数）</td> 
  </tr> 
  <tr> 
   <td> <p><a href="http://www.cplusplus.com/reference/ios/ios_base/setf/" rel="nofollow"><strong>setf</strong></a></p> </td> 
   <td>设置特定的格式标志（公共成员函数）</td> 
  </tr> 
  <tr> 
   <td> <p><a href="http://www.cplusplus.com/reference/ios/ios_base/unsetf/" rel="nofollow"><strong>unsetf</strong></a></p> </td> 
   <td>清除特定格式的标志（公共成员函数）</td> 
  </tr> 
  <tr> 
   <td> <p><a href="http://www.cplusplus.com/reference/ios/ios_base/precision/" rel="nofollow"><strong>precision</strong></a></p> </td> 
   <td>获取/设置浮点十进制精度（公共成员函数）</td> 
  </tr> 
  <tr> 
   <td> <p><a href="http://www.cplusplus.com/reference/ios/ios_base/width/" rel="nofollow"><strong>width</strong></a></p> </td> 
   <td>获取/设置字段宽度（公共成员函数）</td> 
  </tr> 
  <tr> 
   <td> <p><a href="http://www.cplusplus.com/reference/ios/ios_base/imbue/" rel="nofollow"><strong>imbue</strong></a></p> </td> 
   <td>Imbue语言环境（公共成员函数）</td> 
  </tr> 
  <tr> 
   <td> <p><a href="http://www.cplusplus.com/reference/ios/ios_base/getloc/" rel="nofollow"><strong>getloc</strong></a></p> </td> 
   <td>获取当前语言环境（公共成员函数）</td> 
  </tr> 
  <tr> 
   <td> <p><a href="http://www.cplusplus.com/reference/ios/ios_base/xalloc/" rel="nofollow"><strong>xalloc</strong></a></p> </td> 
   <td>获取可扩展数组的新索引[静态]&nbsp;（公共静态成员函数）</td> 
  </tr> 
  <tr> 
   <td> <p><a href="http://www.cplusplus.com/reference/ios/ios_base/iword/" rel="nofollow"><strong>iword</strong></a></p> </td> 
   <td>获取可扩展数组的整数元素（公共成员函数）</td> 
  </tr> 
  <tr> 
   <td> <p><a href="http://www.cplusplus.com/reference/ios/ios_base/pword/" rel="nofollow"><strong>pword</strong></a></p> </td> 
   <td>获取可扩展数组的指针元素（公共成员函数）</td> 
  </tr> 
  <tr> 
   <td> <p><a href="http://www.cplusplus.com/reference/ios/ios_base/register_callback/" rel="nofollow"><strong>register_callback</strong></a></p> </td> 
   <td>注册事件回调函数（公共成员函数）</td> 
  </tr> 
  <tr> 
   <td> <p><a href="http://www.cplusplus.com/reference/ios/ios_base/sync_with_stdio/" rel="nofollow"><strong>sync_with_stdio</strong></a></p> </td> 
   <td>设置每个输入输出操作后是否将标准C++流同步到标准C流</td> 
  </tr> 
 </tbody> 
</table>

[20210303201338634.png]: /images/20220518/f7781e6f71154856ad36659620aad253.png
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[iosfwd]: http://www.cplusplus.com/%3Ciosfwd%3E
[ios]: http://www.cplusplus.com/%3Cios%3E
[iostream]: http://www.cplusplus.com/%3Ciostream%3E
[ios_base]: http://www.cplusplus.com/ios_base
[init]: https://zh.cppreference.com/w/cpp/io/basic_ios/init
[basic_ios]: http://www.cplusplus.com/reference/ios/basic_ios/
[badbit]: https://zh.cppreference.com/w/cpp/io/ios_base/iostate
[rdstate]: https://zh.cppreference.com/w/cpp/io/basic_ios/rdstate
[fail]: https://zh.cppreference.com/w/cpp/io/basic_ios/fail
[20210303205129953.png]: /images/20220518/82f5d864b2a34c21b3fcb4fc627fccf8.png
[20210303210525912.png]: /images/20220518/ef1950333c7e4af8aeaf9e583894b223.png
[20210303210943782.png]: /images/20220518/23e3656a668a4e249bd6a1073b103e1d.png
[20210303211322513.png]: /images/20220518/f8ad9ba11ecb4514842b29bd7add6aa6.png
[rdbuf]: https://zh.cppreference.com/w/cpp/io/basic_ios/rdbuf
[erase_event]: https://zh.cppreference.com/w/cpp/io/ios_base/event
[register_callback]: https://zh.cppreference.com/w/cpp/io/ios_base/register_callback
[std_ios_base_iword]: https://zh.cppreference.com/w/cpp/io/ios_base/iword
[std_ios_base_pword]: https://zh.cppreference.com/w/cpp/io/ios_base/pword
[out]: http://www.cplusplus.com/cout
[20210303212354195.png]: /images/20220518/b2080d8e321a4c2fb5fc493ac9361dd8.png
[2021030321281745.png]: /images/20220518/de1e81d416ae4b32adce02fca65c444d.png
[failure]: https://zh.cppreference.com/w/cpp/io/ios_base/failure
[20210303213738820.png]: /images/20220518/323a34eea7e340b0a84202d4c1eb9c2a.png
[clear]: https://zh.cppreference.com/w/cpp/io/basic_ios/clear
[20210303214025161.png]: /images/20220518/6d00230bcba74c65bbffbb00820edc76.png
[std_use_facet]: http://zh.cppreference.com/w/cpp/locale/use_facet
[std_ctype]: http://zh.cppreference.com/w/cpp/locale/ctype
[std_basic_istream]: https://zh.cppreference.com/w/cpp/io/basic_istream
[std_basic_ostream]: https://zh.cppreference.com/w/cpp/io/basic_ostream
[std_basic_ios]: https://zh.cppreference.com/w/cpp/io/basic_ios