C/C++编程：输入输出库

港控/mmm° 2022-05-18 05:48 261阅读 0赞

# 输入输出库 #

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3poaXpoZW5nZ3Vhbg_size_16_color_FFFFFF_t_70][]

> **iostream库是一个面向对象的库，它使用流提供输入和输出功能**

为了使用流，C++提供了标准库**iostream**，其中包含以下元素：

*  **Basic class templates**
 *  Class template instantiations
 *  Standard objects
 *  Types
 *  Manipulators

## 组织 ##

该库及其类的层次结构分为不同的文件：

* <ios>，<istream>，<ostream>，<streambuf>和<iosfwd>：通常不直接包含在大多数C++程序中。它们描述了层次结构的基类，并被包含派生类的库的其他头文件自动包含。
 * <iostream>：声明用于通过标准输入/输出（包括cin和cout）进行通信的对象
 * <fstream>：定义文件流类（例如模板basic\_ifstream或class ofstream）以及与它们一起使用的内部缓冲区对象（basic\_filebuf）。这些类用于使用流操作文件。
 * <sstream>：此文件中定义的类用于处理[字符串][Link 1]对象，就好像它们是流一样。
 * <iomanip>：声明一些带有参数的标准操作器，这些操纵器与提取和插入运算符一起使用以修改内部标志和格式设置选项

流库是用继承方法建立的输入输出类库

**流库具有两个平行的基类：streambuf和ios类，所有流类均已两者之一作为基类**

### iostream库的元素 (char 实例化) ###

### **Classes**: ###

<table style="width:472px;"> Classes 
 <tbody> 
 <tr> 
 <td> <a href="http://www.cplusplus.com/reference/ios/ios_base/" rel="nofollow">ios_base</a> </td> 
 <td style="width:355px;">流的基类&nbsp;(class )</td> 
 </tr> 
 <tr> 
 <td> <a href="http://www.cplusplus.com/reference/ios/ios/" rel="nofollow">ios</a> </td> 
 <td style="width:355px;">流的基类（与类型有关的组件）&nbsp;(class )</td> 
 </tr> 
 <tr> 
 <td> <a href="http://www.cplusplus.com/reference/istream/istream/" rel="nofollow">istream</a> </td> 
 <td style="width:355px;">输入流 (class )</td> 
 </tr> 
 <tr> 
 <td> <a href="http://www.cplusplus.com/reference/ostream/ostream/" rel="nofollow">ostream</a> </td> 
 <td style="width:355px;">输出流 (class )</td> 
 </tr> 
 <tr> 
 <td> <a href="http://www.cplusplus.com/reference/istream/iostream/" rel="nofollow">iostream</a> </td> 
 <td style="width:355px;">输入输出流 (class )</td> 
 </tr> 
 <tr> 
 <td> <a href="http://www.cplusplus.com/reference/fstream/ifstream/" rel="nofollow">ifstream</a> </td> 
 <td style="width:355px;">输入文件流 (class )</td> 
 </tr> 
 <tr> 
 <td> <a href="http://www.cplusplus.com/reference/fstream/ofstream/" rel="nofollow">ofstream</a> </td> 
 <td style="width:355px;">输出文件流 (class )</td> 
 </tr> 
 <tr> 
 <td> <a href="http://www.cplusplus.com/reference/fstream/fstream/" rel="nofollow">fstream</a> </td> 
 <td style="width:355px;">输入输出文件流 (class )</td> 
 </tr> 
 <tr> 
 <td> <a href="http://www.cplusplus.com/reference/sstream/istringstream/" rel="nofollow">istringstream</a> </td> 
 <td style="width:355px;">字符串输入流 (class )</td> 
 </tr> 
 <tr> 
 <td> <a href="http://www.cplusplus.com/reference/sstream/ostringstream/" rel="nofollow">ostringstream</a> </td> 
 <td style="width:355px;">字符串输出流 (class )</td> 
 </tr> 
 <tr> 
 <td> <a href="http://www.cplusplus.com/reference/sstream/stringstream/" rel="nofollow">stringstream</a> </td> 
 <td style="width:355px;">字符串输入输出流&nbsp; (class )</td> 
 </tr> 
 <tr> 
 <td> <a href="http://www.cplusplus.com/reference/streambuf/streambuf/" rel="nofollow">streambuf</a> </td> 
 <td style="width:355px;">流的基本缓冲区类（class）</td> 
 </tr> 
 <tr> 
 <td> <a href="http://www.cplusplus.com/reference/fstream/filebuf/" rel="nofollow">filebuf</a> </td> 
 <td style="width:355px;">文件流缓冲区（class）</td> 
 </tr> 
 <tr> 
 <td> <a href="http://www.cplusplus.com/reference/sstream/stringbuf/" rel="nofollow">stringbuf</a> </td> 
 <td style="width:355px;">字符串流缓冲区（class）</td> 
 </tr> 
 </tbody> 
</table>

### **Objects**: ###

<table> Objects 
 <tbody> 
 <tr> 
 <td> <a href="http://www.cplusplus.com/reference/iostream/cin/" rel="nofollow">cin</a> </td> 
 <td style="width:317px;">标准输入流(object )</td> 
 <td style="width:579px;">istream类的对象，通常连向键盘，可以重定向</td> 
 </tr> 
 <tr> 
 <td> <a href="http://www.cplusplus.com/reference/iostream/cout/" rel="nofollow">cout</a> </td> 
 <td style="width:317px;">标准输出流(object )</td> 
 <td style="width:579px;">ostream类的对象，通常连向显示器，可以重定向</td> 
 </tr> 
 <tr> 
 <td> <a href="http://www.cplusplus.com/reference/iostream/cerr/" rel="nofollow">cerr</a> </td> 
 <td style="width:317px;">错误的标准输出流(object )</td> 
 <td style="width:579px;">ostream类的对象，连向显示器，不可以重定向</td> 
 </tr> 
 <tr> 
 <td> <a href="http://www.cplusplus.com/reference/iostream/clog/" rel="nofollow">clog</a> </td> 
 <td style="width:317px;">用于日志记录的标准输出流(object )</td> 
 <td style="width:579px;">ostream类的对象，连向打印机，不可以重定向</td> 
 </tr> 
 </tbody> 
</table>

### **Types**: ###

<table style="width:437px;"> Types 
 <tbody> 
 <tr> 
 <td> <a href="http://www.cplusplus.com/reference/ios/fpos/" rel="nofollow">fpos</a> </td> 
 <td style="width:289px;">流位置类模板（class template）</td> 
 </tr> 
 <tr> 
 <td> <a href="http://www.cplusplus.com/reference/ios/streamoff/" rel="nofollow">streamoff</a> </td> 
 <td style="width:289px;">流偏移类型（type）</td> 
 </tr> 
 <tr> 
 <td> <a href="http://www.cplusplus.com/reference/ios/streampos/" rel="nofollow">streampos</a> </td> 
 <td style="width:289px;">流位置类型（type）</td> 
 </tr> 
 <tr> 
 <td> <a href="http://www.cplusplus.com/reference/ios/streamsize/" rel="nofollow">streamsize</a> </td> 
 <td style="width:289px;">流大小类型（type）</td> 
 </tr> 
 </tbody> 
</table>

### **Manipulators**: ###

<table style="width:427px;"> Manipulators 
 <tbody> 
 <tr> 
 <td><a href="http://www.cplusplus.com/reference/ios/boolalpha/" rel="nofollow">boolalpha</a></td> 
 <td style="width:295px;">字母数字布尔值（函数）</td> 
 </tr> 
 <tr> 
 <td><a href="http://www.cplusplus.com/reference/ios/dec/" rel="nofollow">dec</a></td> 
 <td style="width:295px;">使用十进制基数（函数）</td> 
 </tr> 
 <tr> 
 <td><a href="http://www.cplusplus.com/reference/ostream/endl/" rel="nofollow">endl</a></td> 
 <td style="width:295px;">插入换行符并刷新（函数）</td> 
 </tr> 
 <tr> 
 <td><a href="http://www.cplusplus.com/reference/ostream/ends/" rel="nofollow">ends</a></td> 
 <td style="width:295px;">插入空字符（函数）</td> 
 </tr> 
 <tr> 
 <td><a href="http://www.cplusplus.com/reference/ios/fixed/" rel="nofollow">fixed</a></td> 
 <td style="width:295px;">使用固定的浮点表示法（函数）</td> 
 </tr> 
 <tr> 
 <td><a href="http://www.cplusplus.com/reference/ostream/flush-free/" rel="nofollow">flush</a></td> 
 <td style="width:295px;">刷新流缓冲区（函数）</td> 
 </tr> 
 <tr> 
 <td><a href="http://www.cplusplus.com/reference/ios/hex/" rel="nofollow">hex</a></td> 
 <td style="width:295px;">使用十六进制基数（函数）</td> 
 </tr> 
 <tr> 
 <td><a href="http://www.cplusplus.com/reference/ios/internal/" rel="nofollow">internal</a></td> 
 <td style="width:295px;">通过在内部位置插入字符来调整字段（函数）</td> 
 </tr> 
 <tr> 
 <td><a href="http://www.cplusplus.com/reference/ios/left/" rel="nofollow">left</a></td> 
 <td style="width:295px;">将输出调整到左侧（函数）</td> 
 </tr> 
 <tr> 
 <td><a href="http://www.cplusplus.com/reference/ios/noboolalpha/" rel="nofollow">noboolalpha</a></td> 
 <td style="width:295px;">没有字母数字布尔值（函数）</td> 
 </tr> 
 <tr> 
 <td><a href="http://www.cplusplus.com/reference/ios/noshowbase/" rel="nofollow">noshowbase</a></td> 
 <td style="width:295px;">不显示数字基础前缀（函数）</td> 
 </tr> 
 <tr> 
 <td><a href="http://www.cplusplus.com/reference/ios/noshowpoint/" rel="nofollow">noshowpoint</a></td> 
 <td style="width:295px;">不显示小数点（函数）</td> 
 </tr> 
 <tr> 
 <td><a href="http://www.cplusplus.com/reference/ios/noshowpos/" rel="nofollow">noshowpos</a></td> 
 <td style="width:295px;">不显示正号（函数）</td> 
 </tr> 
 <tr> 
 <td><a href="http://www.cplusplus.com/reference/ios/noskipws/" rel="nofollow">noskipws</a></td> 
 <td style="width:295px;">不要跳过空格（函数）</td> 
 </tr> 
 <tr> 
 <td><a href="http://www.cplusplus.com/reference/ios/nounitbuf/" rel="nofollow">nounitbuf</a></td> 
 <td style="width:295px;">插入后请勿强行冲洗（函数）</td> 
 </tr> 
 <tr> 
 <td><a href="http://www.cplusplus.com/reference/ios/nouppercase/" rel="nofollow">nouppercase</a></td> 
 <td style="width:295px;">不生成大写字母（函数）</td> 
 </tr> 
 <tr> 
 <td><a href="http://www.cplusplus.com/reference/ios/oct/" rel="nofollow">oct</a></td> 
 <td style="width:295px;">使用八进制基数（函数）</td> 
 </tr> 
 <tr> 
 <td><a href="http://www.cplusplus.com/reference/iomanip/resetiosflags/" rel="nofollow">resetiosflags</a></td> 
 <td style="width:295px;">重置格式标志（函数）</td> 
 </tr> 
 <tr> 
 <td><a href="http://www.cplusplus.com/reference/ios/right/" rel="nofollow">right</a></td> 
 <td style="width:295px;">将输出调整到右侧（函数）</td> 
 </tr> 
 <tr> 
 <td><a href="http://www.cplusplus.com/reference/ios/scientific/" rel="nofollow">scientific</a></td> 
 <td style="width:295px;">使用科学的浮点表示法（函数）</td> 
 </tr> 
 <tr> 
 <td><a href="http://www.cplusplus.com/reference/iomanip/setbase/" rel="nofollow">setbase</a></td> 
 <td style="width:295px;">设置基本字段标志（函数）</td> 
 </tr> 
 <tr> 
 <td> <a href="http://www.cplusplus.com/reference/iomanip/setfill/" rel="nofollow">setfill</a> </td> 
 <td style="width:295px;">设置填充字符（函数）</td> 
 </tr> 
 <tr> 
 <td> <a href="http://www.cplusplus.com/reference/iomanip/setiosflags/" rel="nofollow">setiosflags</a> </td> 
 <td style="width:295px;">设置格式标志（函数）</td> 
 </tr> 
 <tr> 
 <td> <a href="http://www.cplusplus.com/reference/iomanip/setprecision/" rel="nofollow">setprecision</a> </td> 
 <td style="width:295px;">设置小数精度（函数）</td> 
 </tr> 
 <tr> 
 <td> <a href="http://www.cplusplus.com/reference/iomanip/setw/" rel="nofollow">setw</a> </td> 
 <td style="width:295px;">设置字段宽度（功能）</td> 
 </tr> 
 <tr> 
 <td> <a href="http://www.cplusplus.com/reference/ios/showbase/" rel="nofollow">showbase</a> </td> 
 <td style="width:295px;">显示数字基础前缀（函数）</td> 
 </tr> 
 <tr> 
 <td><a href="http://www.cplusplus.com/reference/ios/showpoint/" rel="nofollow">showpoint</a></td> 
 <td style="width:295px;">显示小数点（函数）</td> 
 </tr> 
 <tr> 
 <td><a href="http://www.cplusplus.com/reference/ios/showpos/" rel="nofollow">showpos</a></td> 
 <td style="width:295px;">显示正号（函数）</td> 
 </tr> 
 <tr> 
 <td><a href="http://www.cplusplus.com/reference/ios/skipws/" rel="nofollow">skipws</a></td> 
 <td style="width:295px;">跳过空格（函数）</td> 
 </tr> 
 <tr> 
 <td> <a href="http://www.cplusplus.com/reference/ios/unitbuf/" rel="nofollow">unitbuf</a> </td> 
 <td style="width:295px;">插入后刷新缓冲区（函数）</td> 
 </tr> 
 <tr> 
 <td> <a href="http://www.cplusplus.com/reference/ios/uppercase/" rel="nofollow">uppercase</a> </td> 
 <td style="width:295px;">生成大写字母（函数）</td> 
 </tr> 
 <tr> 
 <td> <a href="http://www.cplusplus.com/reference/istream/ws/" rel="nofollow">ws</a> </td> 
 <td style="width:295px;">提取空格（函数）</td> 
 </tr> 
 </tbody> 
</table>

# <ios> #

**输入-输出基类**

*  提供了IOStream类的层次结构的基类和类型：

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3poaXpoZW5nZ3Vhbg_size_16_color_FFFFFF_t_70 1][]

*  ios类以及派生类提供使用流类的接口，支持对strambuf的缓冲区输入/输出的格式化或者非格式化转换。

![70][]

**Types**

*  Class templates

<table style="width:500px;"> 
 <tbody> 
 <tr> 
 <td> <a href="http://www.cplusplus.com/reference/ios/basic_ios/" rel="nofollow">basic_ios</a> </td> 
 <td>流的基类（与类型有关的组件）（类模板）</td> 
 </tr> 
 <tr> 
 <td> <a href="http://www.cplusplus.com/reference/ios/fpos/" rel="nofollow">fpos</a> </td> 
 <td>流位置类模板（class template）</td> 
 </tr> 
 </tbody> 
</table>

*  **Classes**

<table style="width:500px;"> 
 <tbody> 
 <tr> 
 <td> <a href="http://www.cplusplus.com/reference/ios/ios/" rel="nofollow">ios</a> </td> 
 <td>流的基类（与类型有关的组件）（类）</td> 
 </tr> 
 <tr> 
 <td> <a href="http://www.cplusplus.com/reference/ios/ios_base/" rel="nofollow">ios_base</a> </td> 
 <td>流的基类（class）</td> 
 </tr> 
 <tr> 
 <td> <a href="http://www.cplusplus.com/reference/ios/wios/" rel="nofollow">wios</a> </td> 
 <td>宽字符流的基类（类）</td> 
 </tr> 
 </tbody> 
</table>

* **Other types** 
 
 
 <table style="width:500px;"> 
 <tbody> 
 <tr> 
 <td> <a href="http://www.cplusplus.com/reference/ios/io_errc/" rel="nofollow">io_errc</a> </td> 
 <td>输入/输出错误条件（枚举类）</td> 
 </tr> 
 <tr> 
 <td> <a href="http://www.cplusplus.com/reference/ios/streamoff/" rel="nofollow">streamoff</a> </td> 
 <td>流偏移类型（type）</td> 
 </tr> 
 <tr> 
 <td> <a href="http://www.cplusplus.com/reference/ios/streampos/" rel="nofollow">streampos</a> </td> 
 <td>流位置类型（type）</td> 
 </tr> 
 <tr> 
 <td> <a href="http://www.cplusplus.com/reference/ios/streamsize/" rel="nofollow">streamsize</a> </td> 
 <td>流大小类型（type）</td> 
 </tr> 
 <tr> 
 <td> <a href="http://www.cplusplus.com/reference/ios/wstreampos/" rel="nofollow">wstreampos</a> </td> 
 <td>宽流位置类型（type）</td> 
 </tr> 
 </tbody> 
 </table>

**格式化标志操纵器（函数）**

*  **独立标志（打开）**：

<table style="width:427px;"> 
 <tbody> 
 <tr> 
 <td><a href="http://www.cplusplus.com/reference/ios/boolalpha/" rel="nofollow">boolalpha</a></td> 
 <td style="width:295px;">字母数字布尔值（函数）</td> 
 </tr> 
 <tr> 
 <td> <a href="http://www.cplusplus.com/reference/ios/showbase/" rel="nofollow">showbase</a> </td> 
 <td style="width:295px;">显示数字基础前缀（函数）</td> 
 </tr> 
 <tr> 
 <td><a href="http://www.cplusplus.com/reference/ios/showpoint/" rel="nofollow">showpoint</a></td> 
 <td style="width:295px;">显示小数点（函数）</td> 
 </tr> 
 <tr> 
 <td><a href="http://www.cplusplus.com/reference/ios/showpos/" rel="nofollow">showpos</a></td> 
 <td style="width:295px;">显示正号（函数）</td> 
 </tr> 
 <tr> 
 <td><a href="http://www.cplusplus.com/reference/ios/skipws/" rel="nofollow">skipws</a></td> 
 <td style="width:295px;">跳过空格（函数）</td> 
 </tr> 
 <tr> 
 <td> <a href="http://www.cplusplus.com/reference/ios/unitbuf/" rel="nofollow">unitbuf</a> </td> 
 <td style="width:295px;">插入后刷新缓冲区（函数）</td> 
 </tr> 
 <tr> 
 <td> <a href="http://www.cplusplus.com/reference/ios/uppercase/" rel="nofollow">uppercase</a> </td> 
 <td style="width:295px;">生成大写字母（函数）</td> 
 </tr> 
 </tbody> 
</table>

*  **独立标志（关闭）**：

<table style="width:427px;"> 
 <tbody> 
 <tr> 
 <td><a href="http://www.cplusplus.com/reference/ios/noboolalpha/" rel="nofollow">noboolalpha</a></td> 
 <td style="width:295px;">没有字母数字布尔值（函数）</td> 
 </tr> 
 <tr> 
 <td><a href="http://www.cplusplus.com/reference/ios/noshowbase/" rel="nofollow">noshowbase</a></td> 
 <td style="width:295px;">不显示数字基础前缀（函数）</td> 
 </tr> 
 <tr> 
 <td><a href="http://www.cplusplus.com/reference/ios/noshowpoint/" rel="nofollow">noshowpoint</a></td> 
 <td style="width:295px;">不显示小数点（函数）</td> 
 </tr> 
 <tr> 
 <td><a href="http://www.cplusplus.com/reference/ios/noshowpos/" rel="nofollow">noshowpos</a></td> 
 <td style="width:295px;">不显示正号（函数）</td> 
 </tr> 
 <tr> 
 <td><a href="http://www.cplusplus.com/reference/ios/noskipws/" rel="nofollow">noskipws</a></td> 
 <td style="width:295px;">不要跳过空格（函数）</td> 
 </tr> 
 <tr> 
 <td><a href="http://www.cplusplus.com/reference/ios/nounitbuf/" rel="nofollow">nounitbuf</a></td> 
 <td style="width:295px;">插入后请勿强行冲洗（函数）</td> 
 </tr> 
 <tr> 
 <td><a href="http://www.cplusplus.com/reference/ios/nouppercase/" rel="nofollow">nouppercase</a></td> 
 <td style="width:295px;">不生成大写字母（函数）</td> 
 </tr> 
 </tbody> 
</table>

*  **数字基本格式标志（“ basefield”标志）**：

<table style="width:427px;"> 
 <tbody> 
 <tr> 
 <td><a href="http://www.cplusplus.com/reference/ios/dec/" rel="nofollow">dec</a></td> 
 <td style="width:295px;">使用十进制基数（函数）</td> 
 </tr> 
 <tr> 
 <td><a href="http://www.cplusplus.com/reference/ios/hex/" rel="nofollow">hex</a></td> 
 <td style="width:295px;">使用十六进制基数（函数）</td> 
 </tr> 
 <tr> 
 <td><a href="http://www.cplusplus.com/reference/ios/oct/" rel="nofollow">oct</a></td> 
 <td style="width:295px;">使用八进制基数（函数）</td> 
 </tr> 
 </tbody> 
</table>

*  **浮点格式标志（“ floatfield”标志）**：

<table style="width:427px;"> 
 <tbody> 
 <tr> 
 <td><a href="http://www.cplusplus.com/reference/ios/fixed/" rel="nofollow">fixed</a></td> 
 <td style="width:295px;">使用固定的浮点表示法（函数）</td> 
 </tr> 
 <tr> 
 <td><a href="http://www.cplusplus.com/reference/ios/scientific/" rel="nofollow">scientific</a></td> 
 <td style="width:295px;">使用科学的浮点表示法（函数）</td> 
 </tr> 
 </tbody> 
</table>

*  **广告格式格式标志（“ adjustfield”标志）**：

<table style="width:427px;"> 
 <tbody> 
 <tr> 
 <td><a href="http://www.cplusplus.com/reference/ios/internal/" rel="nofollow">internal</a></td> 
 <td style="width:295px;">通过在内部位置插入字符来调整字段（函数）</td> 
 </tr> 
 <tr> 
 <td><a href="http://www.cplusplus.com/reference/ios/left/" rel="nofollow">left</a></td> 
 <td style="width:295px;">将输出调整到左侧（函数）</td> 
 </tr> 
 <tr> 
 <td><a href="http://www.cplusplus.com/reference/ios/right/" rel="nofollow">right</a></td> 
 <td style="width:295px;">将输出调整到右侧（函数）</td> 
 </tr> 
 </tbody> 
</table>

# <iosfwd> #

声明对整个iostream中使用的几个类模板的引用。所有此类类模板均在其他标准标题中定义。仅当需要头文件之一的声明而不是其定义时，才显式包括此头文件。

# <istream> #

**输入流**

标头提供标准输入和组合的输入/输出流类：

类模板

<table style="width:500px;"> 
 <tbody> 
 <tr> 
 <td> <a href="http://www.cplusplus.com/reference/istream/basic_istream/" rel="nofollow">basic_istrea</a>m </td> 
 <td>输入流（类模板）</td> 
 </tr> 
 <tr> 
 <td> <a href="http://www.cplusplus.com/reference/istream/basic_iostream/" rel="nofollow">basic_iostrea</a>m </td> 
 <td>输入/输出流（类模板）</td> 
 </tr> 
 </tbody> 
</table>

**Classes**

<table style="width:500px;"> 
 <tbody> 
 <tr> 
 <td> <a href="http://www.cplusplus.com/reference/istream/istream/" rel="nofollow">istream</a> </td> 
 <td>输入流（类）</td> 
 </tr> 
 <tr> 
 <td> <a href="http://www.cplusplus.com/reference/istream/iostream/" rel="nofollow">iostream</a> </td> 
 <td>输入/输出流（类）</td> 
 </tr> 
 <tr> 
 <td> <a href="http://www.cplusplus.com/reference/istream/wistream/" rel="nofollow">wistream</a> </td> 
 <td>输入流（宽）（类）</td> 
 </tr> 
 <tr> 
 <td> <a href="http://www.cplusplus.com/reference/istream/wiostream/" rel="nofollow">wiostream</a> </td> 
 <td>输入/输出流（宽）（类）</td> 
 </tr> 
 </tbody> 
</table>

**输入操纵器（function）**

# <ostream> #

**输出流**

提供标准输出流类的标题：

**类模板**

<table style="width:500px;"> 
 <tbody> 
 <tr> 
 <td> <a href="http://www.cplusplus.com/reference/ostream/basic_ostream/" rel="nofollow">basic_ostrea</a> </td> 
 <td>输出流（类）</td> 
 </tr> 
 </tbody> 
</table>

**Classes**

<table style="width:500px;"> 
 <tbody> 
 <tr> 
 <td> <a href="http://www.cplusplus.com/reference/ostream/ostream/" rel="nofollow">ostream</a> </td> 
 <td>输出流（类）</td> 
 </tr> 
 <tr> 
 <td> <a href="http://www.cplusplus.com/reference/ostream/wostream/" rel="nofollow">wostream</a> </td> 
 <td>输出流（宽）（类）</td> 
 </tr> 
 </tbody> 
</table>

**输入操纵器（function）**

<table style="width:500px;"> 
 <tbody> 
 <tr> 
 <td> <a href="http://www.cplusplus.com/reference/ostream/endl/" rel="nofollow">endl</a> </td> 
 <td>插入换行符并刷新（函数）</td> 
 </tr> 
 <tr> 
 <td> <a href="http://www.cplusplus.com/reference/ostream/ends/" rel="nofollow">ends</a> </td> 
 <td>插入空字符（函数）</td> 
 </tr> 
 <tr> 
 <td> <a href="http://www.cplusplus.com/reference/ostream/flush-free/" rel="nofollow">flush</a> </td> 
 <td>刷新流缓冲区（函数）</td> 
 </tr> 
 </tbody> 
</table>

# <iostream> #

**标准输入/输出流库**

* 定义标准输入/输出流对象的头文件。包含操作所有输入/输出流所需的基本信息，含有cin、cout、cerr、clog对象，提供无格式和格式化的IO
 * `C++11起，`包括`<iostream>`自动也包括`<ios>`，`<streambuf>`，`<istream>`，`<ostream>`和`<iosfwd>`。
 * 标准输入流cin输入到内存，标准输出流cout到屏幕
 * 标准流为用户常用的外部设备提供与内存之间的通信通道，对数据进行解释和传输，提供必要的数据缓冲。

**对象**

*  **窄字符（`char`）**

<table style="width:669px;"> 
 <tbody> 
 <tr> 
 <td> <a href="http://www.cplusplus.com/reference/iostream/cin/" rel="nofollow">cin</a> </td> 
 <td style="width:317px;">标准输入流(object )</td> 
 <td style="width:443px;">istream类的对象，通常连向键盘，可以重定向</td> 
 </tr> 
 <tr> 
 <td> <a href="http://www.cplusplus.com/reference/iostream/cout/" rel="nofollow">cout</a> </td> 
 <td style="width:317px;">标准输出流(object )</td> 
 <td style="width:443px;">ostream类的对象，通常连向显示器，可以重定向</td> 
 </tr> 
 <tr> 
 <td> <a href="http://www.cplusplus.com/reference/iostream/cerr/" rel="nofollow">cerr</a> </td> 
 <td style="width:317px;">错误的标准输出流(object )</td> 
 <td style="width:443px;">ostream类的对象，连向显示器，不可以重定向</td> 
 </tr> 
 <tr> 
 <td> <a href="http://www.cplusplus.com/reference/iostream/clog/" rel="nofollow">clog</a> </td> 
 <td style="width:317px;">用于日志记录的标准输出流(object )</td> 
 <td style="width:443px;">ostream类的对象，连向打印机，不可以重定向</td> 
 </tr> 
 </tbody> 
</table>

*  **宽字符（`wchar_t`）**

<table style="width:402px;"> 
 <tbody> 
 <tr> 
 <td> <a href="http://www.cplusplus.com/reference/iostream/wcin/" rel="nofollow">wcin</a> </td> 
 <td style="width:317px;">标准输入流 （宽）(object )</td> 
 </tr> 
 <tr> 
 <td> <a href="http://www.cplusplus.com/reference/iostream/wcout/" rel="nofollow">wcout</a> </td> 
 <td style="width:317px;">标准输出流（宽）(object )</td> 
 </tr> 
 <tr> 
 <td> <a href="http://www.cplusplus.com/reference/iostream/wcerr/" rel="nofollow">wcerr</a> </td> 
 <td style="width:317px;">错误的标准输出流（宽）(object )</td> 
 </tr> 
 <tr> 
 <td> <a href="http://www.cplusplus.com/reference/iostream/wclog/" rel="nofollow">wclog</a> </td> 
 <td style="width:317px;">用于日志记录的标准输出流（宽）(object )</td> 
 </tr> 
 </tbody> 
</table>

# <streambuf> #

**流缓冲区**

*  提供[streambuf][]类，可与输入/输出流结合使用：
 *  streambuf类提供对缓冲区的低级操作：设置缓冲区，对缓冲区指针操作，向缓冲区存/取字符

![70 1][]

类模板

<table style="width:500px;"> 
 <tbody> 
 <tr> 
 <td> <a href="http://www.cplusplus.com/reference/streambuf/basic_streambuf/" rel="nofollow">basic_streambu</a>f </td> 
 <td>流的基本缓冲区类（类模板）</td> 
 </tr> 
 </tbody> 
</table>

**Classes**

<table style="width:500px;"> 
 <tbody> 
 <tr> 
 <td> <a href="http://www.cplusplus.com/reference/streambuf/streambuf/" rel="nofollow">streambuf</a> </td> 
 <td>流的基本缓冲区类（class）</td> 
 </tr> 
 <tr> 
 <td> <a href="http://www.cplusplus.com/reference/streambuf/wstreambuf/" rel="nofollow">wstreambu</a>f </td> 
 <td>流的基本缓冲区类（宽）（class）</td> 
 </tr> 
 </tbody> 
</table>

# <fstream> #

**文件流**

*  提供文件流类的头
 *  包含建立文件，读写文件的各种操作接口

类模板

<table style="width:500px;"> 
 <tbody> 
 <tr> 
 <td><a href="http://www.cplusplus.com/reference/fstream/basic_ifstream/" rel="nofollow">basic_ifstream</a></td> 
 <td>输入文件流（类模板）</td> 
 </tr> 
 <tr> 
 <td><a href="http://www.cplusplus.com/reference/fstream/basic_ofstream/" rel="nofollow">basic_ofstream</a></td> 
 <td>输出文件流（类模板）</td> 
 </tr> 
 <tr> 
 <td><a href="http://www.cplusplus.com/reference/fstream/basic_fstream/" rel="nofollow">basic_fstream</a></td> 
 <td>文件流（类模板）</td> 
 </tr> 
 <tr> 
 <td><a href="http://www.cplusplus.com/reference/fstream/basic_filebuf/" rel="nofollow">basic_filebuf</a></td> 
 <td>文件流缓冲区（类模板）</td> 
 </tr> 
 </tbody> 
</table>

**Classes**

*  **Narrow characters (`char`)**

<table style="width:500px;"> 
 <tbody> 
 <tr> 
 <td> <a href="http://www.cplusplus.com/reference/fstream/basic_ifstream/" rel="nofollow">basic_ifstream</a> </td> 
 <td>输入文件流类（class）</td> 
 </tr> 
 <tr> 
 <td> <a href="http://www.cplusplus.com/reference/fstream/basic_ofstream/" rel="nofollow">basic_ofstream</a> </td> 
 <td>输出文件流类（class）</td> 
 </tr> 
 <tr> 
 <td> <a href="http://www.cplusplus.com/reference/fstream/basic_fstream/" rel="nofollow">basic_fstream</a> </td> 
 <td>输入/输出文件流类（class）</td> 
 </tr> 
 <tr> 
 <td> <a href="http://www.cplusplus.com/reference/fstream/basic_filebuf/" rel="nofollow">basic_filebuf</a> </td> 
 <td>文件流缓冲区类（class）</td> 
 </tr> 
 </tbody> 
</table>

*  **Wide characters (`wchar_t`)**

<table style="width:500px;"> 
 <tbody> 
 <tr> 
 <td> <a href="http://www.cplusplus.com/reference/fstream/wifstream/" rel="nofollow">wifstream</a> </td> 
 <td>输入文件流类（宽）（class）</td> 
 </tr> 
 <tr> 
 <td> <a href="http://www.cplusplus.com/reference/fstream/wofstream/" rel="nofollow">wofstream</a> </td> 
 <td>输出文件流类（宽）（class）</td> 
 </tr> 
 <tr> 
 <td> <a href="http://www.cplusplus.com/reference/fstream/wfstream/" rel="nofollow">wfstream</a> </td> 
 <td>输入/输出文件流类（宽）（class）</td> 
 </tr> 
 <tr> 
 <td> <a href="http://www.cplusplus.com/reference/fstream/wfilebuf/" rel="nofollow">wfilebuf</a> </td> 
 <td>输入/输出文件流类（宽）（class）</td> 
 </tr> 
 </tbody> 
</table>

# <sstream> #

**String streams**

提供字符串流类的头文件

**类模板**

<table style="width:500px;"> 
 <tbody> 
 <tr> 
 <td> <a href="http://www.cplusplus.com/reference/sstream/basic_istringstream/" rel="nofollow">basic_istringstream</a> </td> 
 <td>输入字符串流（类模板）</td> 
 </tr> 
 <tr> 
 <td> <a href="http://www.cplusplus.com/reference/sstream/basic_ostringstream/" rel="nofollow">basic_ostringstream</a> </td> 
 <td>输出字符串流（类模板）</td> 
 </tr> 
 <tr> 
 <td> <a href="http://www.cplusplus.com/reference/sstream/basic_stringstream/" rel="nofollow">basic_stringstream</a> </td> 
 <td>字符串流（类模板）</td> 
 </tr> 
 <tr> 
 <td> <a href="http://www.cplusplus.com/reference/sstream/basic_stringbuf/" rel="nofollow">basic_stringbuf</a> </td> 
 <td>字符串流缓冲区（类模板）</td> 
 </tr> 
 </tbody> 
</table>

**Classes**

*  **Narrow characters (`char`)**

<table style="width:500px;"> 
 <tbody> 
 <tr> 
 <td> <a href="http://www.cplusplus.com/reference/sstream/istringstream/" rel="nofollow">istringstream</a> </td> 
 <td>输入字符串流（类）</td> 
 </tr> 
 <tr> 
 <td> <a href="http://www.cplusplus.com/reference/sstream/ostringstream/" rel="nofollow">ostringstream</a> </td> 
 <td>输出字符串流（类）</td> 
 </tr> 
 <tr> 
 <td> <a href="http://www.cplusplus.com/reference/sstream/stringstream/" rel="nofollow">stringstream</a> </td> 
 <td>输入/输出字符串流（类）</td> 
 </tr> 
 <tr> 
 <td> <a href="http://www.cplusplus.com/reference/sstream/stringbuf/" rel="nofollow">stringbuf</a> </td> 
 <td>字符串流缓冲区（类）</td> 
 </tr> 
 </tbody> 
</table>

*  **Wide characters (`wchar_t`)**

<table style="width:500px;"> 
 <tbody> 
 <tr> 
 <td> <a href="http://www.cplusplus.com/reference/sstream/istringstream/" rel="nofollow">istringstream</a> </td> 
 <td>输入字符串流（宽）（类）</td> 
 </tr> 
 <tr> 
 <td> <a href="http://www.cplusplus.com/reference/sstream/ostringstream/" rel="nofollow">ostringstream</a> </td> 
 <td>输出字符串流（宽）（类）</td> 
 </tr> 
 <tr> 
 <td> <a href="http://www.cplusplus.com/reference/sstream/stringstream/" rel="nofollow">stringstream</a> </td> 
 <td>输入/输出字符串流（宽）（类）</td> 
 </tr> 
 <tr> 
 <td> <a href="http://www.cplusplus.com/reference/sstream/stringbuf/" rel="nofollow">stringbuf</a> </td> 
 <td>字符串流缓冲区（宽）（类）</td> 
 </tr> 
 </tbody> 
</table>

# <iomanip> #

**IO Manipulators**

*  包含格式化io操作算子，用于指定数据输入和输出的格式

<table style="width:500px;"> 
 <tbody> 
 <tr> 
 <td> <a href="http://www.cplusplus.com/reference/iomanip/setiosflags/" rel="nofollow">setiosflags</a> </td> 
 <td>&nbsp;</td> 
 </tr> 
 <tr> 
 <td> <a href="http://www.cplusplus.com/reference/iomanip/resetiosflags/" rel="nofollow">resetiosflags</a> </td> 
 <td>&nbsp;</td> 
 </tr> 
 <tr> 
 <td> <a href="http://www.cplusplus.com/reference/iomanip/setbase/" rel="nofollow">setbase</a> </td> 
 <td>&nbsp;</td> 
 </tr> 
 <tr> 
 <td> <a href="http://www.cplusplus.com/reference/iomanip/setfill/" rel="nofollow">setfill</a> </td> 
 <td>&nbsp;</td> 
 </tr> 
 <tr> 
 <td> <a href="http://www.cplusplus.com/reference/iomanip/setprecision/" rel="nofollow">setprecision</a> </td> 
 <td>&nbsp;</td> 
 </tr> 
 <tr> 
 <td> <a href="http://www.cplusplus.com/reference/iomanip/setw/" rel="nofollow">setw</a> </td> 
 <td>&nbsp;</td> 
 </tr> 
 <tr> 
 <td> <a href="http://www.cplusplus.com/reference/iomanip/get_money/" rel="nofollow">get_money&nbsp;</a> </td> 
 <td>&nbsp;</td> 
 </tr> 
 <tr> 
 <td> <a href="http://www.cplusplus.com/reference/iomanip/put_money/" rel="nofollow">put_money&nbsp;</a> </td> 
 <td>&nbsp;</td> 
 </tr> 
 <tr> 
 <td> <a href="http://www.cplusplus.com/reference/iomanip/get_time/" rel="nofollow">get_time&nbsp;</a> </td> 
 <td>&nbsp;</td> 
 </tr> 
 <tr> 
 <td> <a href="http://www.cplusplus.com/reference/iomanip/put_time/" rel="nofollow">put_time&nbsp;</a> </td> 
 <td>&nbsp;</td> 
 </tr> 
 </tbody> 
</table>

=====================================================================================================================

1、输入输出流

*  IO流类库提供对象之间的数据交互服务
 *  流类库预定义了一批流对象，连接常用的外部设备
 *  可以定义所需的IO流对象，使用流库提供的工作方式实现数据传输。

2、流类和流对象\[比如视频流，音频流\]

*  程序中，对数据的输入/输出是以字节流实现的
 *  应用程序对字节序做出各种数据解释
 *  IO系统的任务就是在内存和外部设备之间稳定可靠的传输数据和解释数据
 *  流类对象可以建立和删除，可以从流中获取数据和向流添加数据

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3poaXpoZW5nZ3Vhbg_size_16_color_FFFFFF_t_70]: /images/20220518/8c336113c7b04b7b9efad9d5cd4fee60.png
[Link 1]: http://www.cplusplus.com/string
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3poaXpoZW5nZ3Vhbg_size_16_color_FFFFFF_t_70 1]: /images/20220518/8a85653c2a6246f79ce331db1b9742ea.png
[70]: /images/20220518/8f4537016ca4494fa84496ad0c8ef63a.png
[streambuf]: http://www.cplusplus.com/streambuf
[70 1]: /images/20220518/1672fefcbca34a28b65ed03e9a95f254.png