字符特性char_traits定義，及其特化版本char_traits，char_traits

// iosfwd standard header

#if     _MSC_VER > 1000
#pragma once
#endif

#ifndef _IOSFWD_
#define _IOSFWD_
#include <cstdio>
#include <cstring>
#include <cwchar>
#include <xstddef>

#ifdef  _MSC_VER
#pragma pack(push,8)
#endif  /* _MSC_VER */
_STD_BEGIN
                // STREAM POSITIONING TYPES (from <streambuf>)
typedef long streamoff;
const streamoff _BADOFF = -1;
typedef int streamsize;
extern _CRTIMP const fpos_t _Fpz;
                // TEMPLATE CLASS fpos (from <streambuf>)
template<class _St>
        class fpos {
        typedef fpos<_St> _Myt;
public:
#ifdef  _MT
        fpos(streamoff _O = 0)
                : _Off(_O), _Fpos(_Fpz)
                {_Lockit _Lk;
                _State = _Stz; }
#else
        fpos(streamoff _O = 0)
                : _Off(_O), _Fpos(_Fpz), _State(_Stz) {}
#endif
        fpos(_St _S, fpos_t _F)
                : _Off(0), _Fpos(_F), _State(_S) {}
        _St state() const
                {return (_State); }
        void state(_St _S)
                {_State = _S; }
        fpos_t get_fpos_t() const
                {return (_Fpos); }
        operator streamoff() const
                {return (_Off + _FPOSOFF(_Fpos)); }
        streamoff operator-(const _Myt& _R) const
                {return ((streamoff)*this - (streamoff)_R); }
        _Myt& operator+=(streamoff _O)
                {_Off += _O;
                return (*this); }
        _Myt& operator-=(streamoff _O)
                {_Off -= _O;
                return (*this); }
        _Myt operator+(streamoff _O) const
                {_Myt _Tmp = *this;
                return (_Tmp += _O); }
        _Myt operator-(streamoff _O) const
                {_Myt _Tmp = *this;
                return (_Tmp -= _O); }
        bool operator==(const _Myt& _R) const
                {return ((streamoff)*this == (streamoff)_R); }
        bool operator!=(const _Myt& _R) const
                {return (!(*this == _R)); }
private:
        static _St _Stz;
        streamoff _Off;
        fpos_t _Fpos;
        _St _State;
        };
template<class _St>
        _St fpos<_St>::_Stz;
typedef fpos<mbstate_t> streampos;
typedef streampos wstreampos;
                // TEMPLATE STRUCT char_traits (FROM <string>)
template<class _E>
        struct char_traits {
        typedef _E char_type;
        typedef _E int_type;
        typedef streampos pos_type;
        typedef streamoff off_type;
        typedef mbstate_t state_type;
        static void __cdecl assign(_E& _X, const _E& _Y)
                {_X = _Y; }
        static bool __cdecl eq(const _E& _X, const _E& _Y)
                {return (_X == _Y); }
        static bool __cdecl lt(const _E& _X, const _E& _Y)
                {return (_X < _Y); }
        static int __cdecl compare(const _E *_U, const _E *_V, size_t _N)
                {for (size_t _I = 0; _I < _N; ++_I, ++_U, ++_V)
                        if (!eq(*_U, *_V))
                                return (lt(*_U, *_V) ? -1 : +1);
                return (0); }
        static size_t __cdecl length(const _E *_U)
                {size_t _N;
                for (_N = 0; !eq(*_U, _E(0)); ++_U)
                        ++_N;
                return (_N); }
        static _E * __cdecl copy(_E *_U, const _E *_V, size_t _N)
                {_E *_S = _U;
                for (; 0 < _N; --_N, ++_U, ++_V)
                        assign(*_U, *_V);
                return (_S); }
        static const _E * __cdecl find(const _E *_U, size_t _N,
                const _E& _C)
                {for (; 0 < _N; --_N, ++_U)
                        if (eq(*_U, _C))
                                return (_U);
                return (0); }
        static _E * __cdecl move(_E *_U, const _E *_V, size_t _N)
                {_E *_Ans = _U;
                if (_V < _U && _U < _V + _N)
                        for (_U += _N, _V += _N; 0 < _N; --_N)
                                assign(*--_U, *--_V);
                else
                        for (; 0 < _N; --_N, ++_U, ++_V)
                                assign(*_U, *_V);
                return (_Ans); }
        static _E * __cdecl assign(_E *_U, size_t _N, const _E& _C)
                {_E *_Ans = _U;
                for (; 0 < _N; --_N, ++_U)
                        assign(*_U, _C);
                return (_Ans); }
        static _E __cdecl to_char_type(const int_type& _C)
                {return ((_E)_C); }
        static int_type __cdecl to_int_type(const _E& _C)
                {return ((int_type)_C); }
        static bool __cdecl eq_int_type(const int_type& _X,
                const int_type& _Y)
                {return (_X == _Y); }
        static int_type __cdecl eof()
                {return (EOF); }
        static int_type __cdecl not_eof(const int_type& _C)
                {return (_C != eof() ? _C : !eof()); }
        };
                // STRUCT char_traits<wchar_t>
template<> struct _CRTIMP char_traits<wchar_t> {
        typedef wchar_t _E;
        typedef _E char_type;   // for overloads
        typedef wint_t int_type;
        typedef streampos pos_type;
        typedef streamoff off_type;
        typedef mbstate_t state_type;
        static void __cdecl assign(_E& _X, const _E& _Y)
                {_X = _Y; }
        static bool __cdecl eq(const _E& _X, const _E& _Y)
                {return (_X == _Y); }
        static bool __cdecl lt(const _E& _X, const _E& _Y)
                {return (_X < _Y); }
        static int __cdecl compare(const _E *_U, const _E *_V, size_t _N)
                {return (wmemcmp(_U, _V, _N)); }
        static size_t __cdecl length(const _E *_U)
                {return (wcslen(_U)); }
        static _E *__cdecl copy(_E *_U, const _E *_V, size_t _N)
                {return (wmemcpy(_U, _V, _N)); }
        static const _E * __cdecl find(const _E *_U, size_t _N,
                const _E& _C)
                {return ((const _E *)wmemchr(_U, _C, _N)); }
        static _E * __cdecl move(_E *_U, const _E *_V, size_t _N)
                {return (wmemmove(_U, _V, _N)); }
        static _E * __cdecl assign(_E *_U, size_t _N, const _E& _C)
                {return (wmemset(_U, _C, _N)); }
        static _E __cdecl to_char_type(const int_type& _C)
                {return ((_E)_C); }
        static int_type __cdecl to_int_type(const _E& _C)
                {return ((int_type)_C); }
        static bool __cdecl eq_int_type(const int_type& _X,
                const int_type& _Y)
                {return (_X == _Y); }
        static int_type __cdecl eof()
                {return (WEOF); }
        static int_type __cdecl not_eof(const int_type& _C)
                {return (_C != eof() ? _C : !eof()); }
        };
                // STRUCT char_traits<char> (FROM <string>)
template<> struct _CRTIMP char_traits<char> {
        typedef char _E;
        typedef _E char_type;
        typedef int int_type;
        typedef streampos pos_type;
        typedef streamoff off_type;
        typedef mbstate_t state_type;
        static void __cdecl assign(_E& _X, const _E& _Y)
                {_X = _Y; }
        static bool __cdecl eq(const _E& _X, const _E& _Y)
                {return (_X == _Y); }
        static bool __cdecl lt(const _E& _X, const _E& _Y)
                {return (_X < _Y); }
        static int __cdecl compare(const _E *_U, const _E *_V, size_t _N)
                {return (memcmp(_U, _V, _N)); }
        static size_t __cdecl length(const _E *_U)
                {return (strlen(_U)); }
        static _E * __cdecl copy(_E *_U, const _E *_V, size_t _N)
                {return ((_E *)memcpy(_U, _V, _N)); }
        static const _E * __cdecl find(const _E *_U, size_t _N,
                const _E& _C)
                {return ((const _E *)memchr(_U, _C, _N)); }
        static _E * __cdecl move(_E *_U, const _E *_V, size_t _N)
                {return ((_E *)memmove(_U, _V, _N)); }
        static _E * __cdecl assign(_E *_U, size_t _N, const _E& _C)
                {return ((_E *)memset(_U, _C, _N)); }
        static _E __cdecl to_char_type(const int_type& _C)
                {return ((_E)_C); }
        static int_type __cdecl to_int_type(const _E& _C)
                {return ((int_type)((unsigned char)_C)); }
        static bool __cdecl eq_int_type(const int_type& _X,
                const int_type& _Y)
                {return (_X == _Y); }
        static int_type __cdecl eof()
                {return (EOF); }
        static int_type __cdecl not_eof(const int_type& _C)
                {return (_C != eof() ? _C : !eof()); }
        };
                // FORWARD REFERENCES
template<class T>
        class allocator;
class ios_base;
template<class _E, class _Tr = char_traits<_E> >
        class basic_ios;
template<class _E, class _Tr = char_traits<_E> >
        class istreambuf_iterator;
template<class _E, class _Tr = char_traits<_E> >
        class ostreambuf_iterator;
template<class _E, class _Tr = char_traits<_E> >
        class basic_streambuf;
template<class _E, class _Tr = char_traits<_E> >
        class basic_istream;
template<class _E, class _Tr = char_traits<_E> >
        class basic_ostream;
template<class _E, class _Tr = char_traits<_E> >
        class basic_iostream;
template<class _E, class _Tr = char_traits<_E>,
        class _A = allocator<_E> >
        class basic_stringbuf;
template<class _E, class _Tr = char_traits<_E>,
        class _A = allocator<_E> >
        class basic_istringstream;
template<class _E, class _Tr = char_traits<_E>,
        class _A = allocator<_E> >
        class basic_ostringstream;
template<class _E, class _Tr = char_traits<_E>,
        class _A = allocator<_E> >
        class basic_stringstream;
template<class _E, class _Tr = char_traits<_E> >
        class basic_filebuf;
template<class _E, class _Tr = char_traits<_E> >
        class basic_ifstream;
template<class _E, class _Tr = char_traits<_E> >
        class basic_ofstream;
template<class _E, class _Tr = char_traits<_E> >
        class basic_fstream;

                // char TYPEDEFS
typedef basic_ios<char, char_traits<char> > ios;
typedef basic_streambuf<char, char_traits<char> > streambuf;
typedef basic_istream<char, char_traits<char> > istream;
typedef basic_ostream<char, char_traits<char> > ostream;
typedef basic_iostream<char, char_traits<char> > iostream;
typedef basic_stringbuf<char, char_traits<char>,
        allocator<char> > stringbuf;
typedef basic_istringstream<char, char_traits<char>,
        allocator<char> > istringstream;
typedef basic_ostringstream<char, char_traits<char>,
        allocator<char> > ostringstream;
typedef basic_stringstream<char, char_traits<char>,
        allocator<char> > stringstream;
typedef basic_filebuf<char, char_traits<char> > filebuf;
typedef basic_ifstream<char, char_traits<char> > ifstream;
typedef basic_ofstream<char, char_traits<char> > ofstream;
typedef basic_fstream<char, char_traits<char> > fstream;
                // wchar_t TYPEDEFS
typedef basic_ios<wchar_t, char_traits<wchar_t> > wios;
typedef basic_streambuf<wchar_t, char_traits<wchar_t> >
        wstreambuf;
typedef basic_istream<wchar_t, char_traits<wchar_t> > wistream;
typedef basic_ostream<wchar_t, char_traits<wchar_t> > wostream;
typedef basic_iostream<wchar_t, char_traits<wchar_t> > wiostream;
typedef basic_stringbuf<wchar_t, char_traits<wchar_t>,
        allocator<wchar_t> > wstringbuf;
typedef basic_istringstream<wchar_t, char_traits<wchar_t>,
        allocator<wchar_t> > wistringstream;
typedef basic_ostringstream<wchar_t, char_traits<wchar_t>,
        allocator<wchar_t> > wostringstream;
typedef basic_stringstream<wchar_t, char_traits<wchar_t>,
        allocator<wchar_t> > wstringstream;
typedef basic_filebuf<wchar_t, char_traits<wchar_t> > wfilebuf;
typedef basic_ifstream<wchar_t, char_traits<wchar_t> > wifstream;
typedef basic_ofstream<wchar_t, char_traits<wchar_t> > wofstream;
typedef basic_fstream<wchar_t, char_traits<wchar_t> > wfstream;

#ifdef  _DLL
template<class _E, class _II >
    class num_get;
template<class _E, class _OI >
    class num_put;
template<class _E>
    class collate;

typedef num_get<char, istreambuf_iterator<char, char_traits<char> > > numget;
typedef num_get<wchar_t, istreambuf_iterator<wchar_t, char_traits<wchar_t> > >
                                                                                                                                          wnumget;
typedef num_put<char, ostreambuf_iterator<char, char_traits<char> > > numput;
typedef num_put<wchar_t, ostreambuf_iterator<wchar_t, char_traits<wchar_t> > >
                                                                                                                                          wnumput;
typedef collate<char> ncollate;
typedef collate<wchar_t> wcollate;

#endif

_STD_END
#ifdef  _MSC_VER
#pragma pack(pop)
#endif  /* _MSC_VER */

#endif /* _IOSFWD_ */

/*
 * Copyright (c) 1995 by P.J. Plauger.  ALL RIGHTS RESERVED. 
 * Consult your license regarding permissions and restrictions.
 */