<?xml version="1.0" encoding="utf-8"?> cout internal

cout internal

先看看cout是这么定义的： istream cout(&fout)

//C:\Program Files (x86)\Microsoft Visual Studio 10.0\VC\crt\src\cout.cpp// cout -- initialize standard output stream#include 
     
      #include 
      
       #pragma warning(disable: 4074)#pragma init_seg(compiler)static std::_Init_locks  initlocks;_STD_BEGIN        // OBJECT DECLARATIONS__PURE_APPDOMAIN_GLOBAL static filebuf fout(_cpp_stdout);#if defined(_M_CEE_PURE)__PURE_APPDOMAIN_GLOBAL extern ostream cout(&fout);#else__PURE_APPDOMAIN_GLOBAL extern _CRTDATA2 ostream cout(&fout);#endif        // INITIALIZATION CODEstruct _Init_cout    {   // ensures that cout is initialized    __CLR_OR_THIS_CALL _Init_cout()        {   // initialize cout        _Ptr_cout = &cout;        if (_Ptr_cin != 0)            _Ptr_cin->tie(_Ptr_cout);        if (_Ptr_cerr != 0)            _Ptr_cerr->tie(_Ptr_cout);        if (_Ptr_clog != 0)            _Ptr_clog->tie(_Ptr_cout);        }    };__PURE_APPDOMAIN_GLOBAL static _Init_cout init_cout;_STD_END/* * Copyright (c) 1992-2007 by P.J. Plauger.  ALL RIGHTS RESERVED. * Consult your license regarding permissions and restrictions. V5.03:0009 */
      
     

再看看 _cpp_stdout 是怎么回事？

//C:\Program Files (x86)\Microsoft Visual Studio 10.0\VC\crt\src\yvals.h   #define _cpp_stdin  (&(__iob_func())[0])   #define _cpp_stdout (&(__iob_func())[1])   #define _cpp_stderr (&(__iob_func())[2])   #define _cpp_isleadbyte(c) (__pctype_func()[(unsigned char)(c)] & _LEADBYTE)

关于 __iob_func(): __iob_func() returns a pointer to the array of FILE descriptors that holds stdin, stdout, stderr and any FILE objects opened through the C runtime library. See the MSVC runtime library source _file.c.

//C:\Program Files (x86)\Microsoft Visual Studio 10.0\VC\crt\src\_file.c/* * FILE descriptors; preset for stdin/out/err (note that the __tmpnum field * is not initialized) */FILE _iob[_IOB_ENTRIES] = {        /* _ptr, _cnt, _base,  _flag, _file, _charbuf, _bufsiz */        /* stdin (_iob[0]) */        { _bufin, 0, _bufin, _IOREAD | _IOYOURBUF, 0, 0, _INTERNAL_BUFSIZ },        /* stdout (_iob[1]) */        { NULL, 0, NULL, _IOWRT, 1, 0, 0 },        /* stderr (_iob[3]) */        { NULL, 0, NULL, _IOWRT, 2, 0, 0 },};/* * Initializer and terminator for stdio */int  __cdecl __initstdio(void);void __cdecl __endstdio(void);_CRTALLOC(".CRT$XIC") static _PIFV pinit = __initstdio;_CRTALLOC(".CRT$XPXA") static _PVFV pterm = __endstdio;

//C:\Program Files (x86)\Microsoft Visual Studio 10.0\VC\crt\src\internal.hstruct _iobuf {        char *_ptr;        int   _cnt;        char *_base;        int   _flag;        int   _file;        int   _charbuf;        int   _bufsiz;        char *_tmpfname;        };typedef struct _iobuf FILE;

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