Namespaces
Variants

Standard library header <iosfwd>

From cppreference.net
C++
Standard library headers

此头文件包含对 输入/输出 库的前向声明。

前向声明

定义于头文件 <string>
std::char_traits 描述字符类型特性的类模板 (类模板)
std:: char_traits < char > (类模板特化)
std:: char_traits < wchar_t > (类模板特化)
std:: char_traits < char8_t > (C++20) (类模板特化)
std:: char_traits < char16_t > (C++11) (类模板特化)
std:: char_traits < char32_t > (C++11) (类模板特化)
定义于头文件 <memory>
默认分配器
(类模板)
定义于头文件 <ios>
管理任意流缓冲区
(类模板)
表示流或文件中的绝对位置
(类模板)
定义于头文件 <streambuf>
抽象原始设备
(类模板)
定义于头文件 <ostream>
包装给定抽象设备 ( std::basic_streambuf )
并提供高级输出接口
(类模板)
定义于头文件 <istream>
包装给定抽象设备 ( std::basic_streambuf )
并提供高级输入接口
(类模板)
包装给定抽象设备 ( std::basic_streambuf )
并提供高级输入/输出接口
(类模板)
定义于头文件 <fstream>
实现原始文件设备
(类模板)
实现高级文件流输入操作
(类模板)
实现高级文件流输出操作
(类模板)
实现高级文件流输入/输出操作
(类模板)
定义于头文件 <sstream>
实现原始字符串设备
(类模板)
实现高级字符串流输入操作
(类模板)
实现高级字符串流输出操作
(类模板)
实现高级字符串流输入/输出操作
(类模板)
定义于头文件 <syncstream>
(C++20) </

概要 

namespace std {
  template<class CharT> struct char_traits;
  template<> struct char_traits<char>;
  template<> struct char_traits<char8_t>;
  template<> struct char_traits<char16_t>;
  template<> struct char_traits<char32_t>;
  template<> struct char_traits<wchar_t>;
  template<class T> class allocator;
  template<class CharT, class Traits = char_traits<CharT>>
    class basic_ios;
  template<class CharT, class Traits = char_traits<CharT>>
    class basic_streambuf;
  template<class CharT, class Traits = char_traits<CharT>>
    class basic_istream;
  template<class CharT, class Traits = char_traits<CharT>>
    class basic_ostream;
  template<class CharT, class Traits = char_traits<CharT>>
    class basic_iostream;
  template<class CharT, class Traits = char_traits<CharT>,
           class Allocator = allocator<CharT>>
    class basic_stringbuf;
  template<class CharT, class Traits = char_traits<CharT>,
           class Allocator = allocator<CharT>>
    class basic_istringstream;
  template<class CharT, class Traits = char_traits<CharT>,
           class Allocator = allocator<CharT>>
    class basic_ostringstream;
  template<class CharT, class Traits = char_traits<CharT>,
           class Allocator = allocator<CharT>>
    class basic_stringstream;
  template<class CharT, class Traits = char_traits<CharT>>
    class basic_filebuf;
  template<class CharT, class Traits = char_traits<CharT>>
    class basic_ifstream;
  template<class CharT, class Traits = char_traits<CharT>>
    class basic_ofstream;
  template<class CharT, class Traits = char_traits<CharT>>
    class basic_fstream;
  template<class CharT, class Traits = char_traits<CharT>,
           class Allocator = allocator<CharT>>
    class basic_syncbuf;
  template<class CharT, class Traits = char_traits<CharT>,
           class Allocator = allocator<CharT>>
    class basic_osyncstream;
  template<class CharT, class Traits = char_traits<CharT>>
    class basic_spanbuf;
  template<class CharT, class Traits = char_traits<CharT>>
    class basic_ispanstream;
  template<class CharT, class Traits = char_traits<CharT>>
    class basic_ospanstream;
  template<class CharT, class Traits = char_traits<CharT>>
    class basic_spanstream;
  template<class CharT, class Traits = char_traits<CharT>>
    class istreambuf_iterator;
  template<class CharT, class Traits = char_traits<CharT>>
    class ostreambuf_iterator;
  using ios  = basic_ios<char>;
  using wios = basic_ios<wchar_t>;
  using streambuf = basic_streambuf<char>;
  using istream   = basic_istream<char>;
  using ostream   = basic_ostream<char>;
  using iostream  = basic_iostream<char>;
  using stringbuf     = basic_stringbuf<char>;
  using istringstream = basic_istringstream<char>;
  using ostringstream = basic_ostringstream<char>;
  using stringstream  = basic_stringstream<char>;
  using filebuf  = basic_filebuf<char>;
  using ifstream = basic_ifstream<char>;
  using ofstream = basic_ofstream<char>;
  using fstream  <span