C++ 库 - <iosfwd>

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描述

它用于输入输出前向声明，该头为标准输入/输出库的类型提供前向声明。

定义

以下是 iosfwd 函数的定义。

 #define _GLIBCXX_IOSFWD

例子

C++98

下面的例子解释了iosfwd功能。

amespace std {
   template<class charT> struct char_traits;
   template<> class char_traits<char>;
   template<> class 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 Alloc=allocator<charT> >
      class basic_stringbuf;
   template <class charT, class traits=char_traits<charT>, class Alloc=allocator<charT> > 
      class basic_istringstream;
   template <class charT, class traits=char_traits<charT>, class Alloc=allocator<charT> >
      class basic_ostringstream;
   template <class charT, class traits=char_traits<charT>, class Alloc=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 istreambuf_iterator;
   template <class charT, class traits=char_traits<charT> > class ostreambuf_iterator;

   template<class stateT> class fpos;

   typedef basic_ios<char>              ios;
   typedef basic_streambuf<char>        streambuf;
   typedef basic_istream<char>          istream;
   typedef basic_ostream<char>          ostream;
   typedef basic_iostream<char>         iostream;
   typedef basic_stringbuf<char>        stringbuf;
   typedef basic_istringstream<char>    istringstream;
   typedef basic_ostringstream<char>    ostringstream;
   typedef basic_stringstream<char>     stringstream;
   typedef basic_filebuf<char>          filebuf;
   typedef basic_ifstream<char>         ifstream;
   typedef basic_ofstream<char>         ofstream;
   typedef basic_fstream<char>          fstream;

   typedef basic_ios<wchar_t>           wios;
   typedef basic_streambuf<wchar_t>     wstreambuf;
   typedef basic_istream<wchar_t>       wistream;
   typedef basic_ostream<wchar_t>       wostream;
   typedef basic_iostream<wchar_t>      wiostream;
   typedef basic_stringbuf<wchar_t>     wstringbuf;
   typedef basic_istringstream<wchar_t> wistringstream;
   typedef basic_ostringstream<wchar_t> wostringstream;
   typedef basic_stringstream<wchar_t>  wstringstream;
   typedef basic_filebuf<wchar_t>       wfilebuf;
   typedef basic_ifstream<wchar_t>      wifstream;
   typedef basic_ofstream<wchar_t>      wofstream;
   typedef basic_fstream<wchar_t>       wfstream;

   typedef fpos<mbstate_t> streampos;
   typedef fpos<mbstate_t> wstreampos;
}

C++11

下面的例子解释了iosfwd功能。

namespace std {
   template<class charT> struct char_traits;
   template<> class char_traits<char>;
   template<> class char_traits<char16_t>;
   template<> class char_traits<char32_t>;
   template<> class 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 Alloc=allocator<charT> >
      class basic_stringbuf;
   template <class charT, class traits=char_traits<charT>, class Alloc=allocator<charT> > 
      class basic_istringstream;
   template <class charT, class traits=char_traits<charT>, class Alloc=allocator<charT> >
      class basic_ostringstream;
   template <class charT, class traits=char_traits<charT>, class Alloc=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 istreambuf_iterator;
   template <class charT, class traits=char_traits<charT> > class ostreambuf_iterator;

  template<class stateT> class fpos;

   typedef basic_ios<char>              ios;
   typedef basic_streambuf<char>        streambuf;
   typedef basic_istream<char>          istream;
   typedef basic_ostream<char>          ostream;
   typedef basic_iostream<char>         iostream;
   typedef basic_stringbuf<char>        stringbuf;
   typedef basic_istringstream<char>    istringstream;
   typedef basic_ostringstream<char>    ostringstream;
   typedef basic_stringstream<char>     stringstream;
   typedef basic_filebuf<char>          filebuf;
   typedef basic_ifstream<char>         ifstream;
   typedef basic_ofstream<char>         ofstream;
   typedef basic_fstream<char>          fstream;

   typedef basic_ios<wchar_t>           wios;
   typedef basic_streambuf<wchar_t>     wstreambuf;
   typedef basic_istream<wchar_t>       wistream;
   typedef basic_ostream<wchar_t>       wostream;
   typedef basic_iostream<wchar_t>      wiostream;
   typedef basic_stringbuf<wchar_t>     wstringbuf;
   typedef basic_istringstream<wchar_t> wistringstream;
   typedef basic_ostringstream<wchar_t> wostringstream;
   typedef basic_stringstream<wchar_t>  wstringstream;
   typedef basic_filebuf<wchar_t>       wfilebuf;
   typedef basic_ifstream<wchar_t>      wifstream;
   typedef basic_ofstream<wchar_t>      wofstream;
   typedef basic_fstream<wchar_t>       wfstream;

   typedef fpos<mbstate_t> streampos;
   typedef fpos<mbstate_t> wstreampos;
}