user-0 提问: 有关windows缓冲模式的问题

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user: user-1
content: windows系统默认无缓冲模式

user: user-2
content: fflush Flushes a stream.  int fflush( FILE *stream );  Function Required Header Compatibility  fflush <stdio.h> ANSI, Win 95, Win NT    For additional compatibility information, see Compatibility in the Introduction.  Libraries  LIBC.LIB Single thread static library, retail version  LIBCMT.LIB Multithread static library, retail version  MSVCRT.LIB Import library for MSVCRT.DLL, retail version    Return Value  fflush returns 0 if the buffer was successfully flushed. The value 0 is also returned in cases in which the specified stream has no buffer or is open for reading only. A return value of EOF indicates an error.  Note   If fflush returns EOF, data may have been lost due to a write failure. When setting up a critical error handler, it is safest to turn buffering off with the setvbuf function or to use low-level I/O routines such as _open, _close, and _write instead of the stream I/O functions.  Parameter  stream  Pointer to FILE structure  Remarks  The fflush function flushes a stream. If the file associated with stream is open for output, fflush writes to that file the contents of the buffer associated with the stream. If the stream is open for input, fflush clears the contents of the buffer. fflush negates the effect of any prior call to ungetc against stream. Also, fflush(NULL) flushes all streams opened for output. The stream remains open after the call. fflush has no effect on an unbuffered stream.  Buffers are normally maintained by the operating system, which determines the optimal time to write the data automatically to disk: when a buffer is full, when a stream is closed, or when a program terminates normally without closing the stream. The commit-to-disk feature of the run-time library lets you ensure that critical data is written directly to disk rather than to the operating-system buffers. Without rewriting an existing program, you can enable this feature by linking the program’s object files with COMMODE.OBJ. In the resulting executable file, calls to _flushall write the contents of all buffers to disk. Only _flushall and fflush are affected by COMMODE.OBJ.  For information about controlling the commit-to-disk feature, see Stream I/O, fopen, and _fdopen.  Example  /* FFLUSH.C */  #include <stdio.h> #include <conio.h>  void main( void ) {    int integer;    char string[81];     /* Read each word as a string. */    printf( "Enter a sentence of four words with scanf: " );    for( integer = 0; integer < 4; integer++ )    {       scanf( "%s", string );       printf( "%s\n", string );    }     /* You must flush the input buffer before using gets. */    fflush( stdin );    printf( "Enter the same sentence with gets: " );    gets( string );    printf( "%s\n", string ); }   Output  Enter a sentence of four words with scanf: This is a test This is a test Enter the same sentence with gets: This is a test This is a test   Stream I/O Routines  See Also   fclose, _flushall, setvbuf

user: user-3
content: 等你调用完colse，才有内容送到文件。 也就是全缓冲模式。

user: user-4
content: 缓冲分为：无缓冲，行缓冲和全缓冲；文件写（若是默认状态）是全缓冲模式（当数据在缓存里达到一定数值则将缓存里的数值刷到文件里），缓存大小是可以配置，一般是是页的整数倍； 标准输入和输出一般是行缓冲； 对于缓存的分类，建议从网上详细查阅一下；

user: user-5
content: http://en.cppreference.com/w/c/io/setvbuf