flushall.md

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_flushall | Microsoft Docs		11/04/2016			cpp-standard-libraries		article	_flushall	msvcrt.dll msvcr80.dll msvcr90.dll msvcr100.dll msvcr100_clr0400.dll msvcr110.dll msvcr110_clr0400.dll msvcr120.dll msvcr120_clr0400.dll ucrtbase.dll api-ms-win-crt-stdio-l1-1-0.dll	DLLExport	_flushall	C++	flushall function flushing streams streams, flushing _flushall function	2cd73562-6d00-4ca2-b13c-80d0ae7870b5	16	corob-msft	corob	ghogen

_flushall

Flushes all streams; clears all buffers.

Syntax

int _flushall( void );  

Return Value

_flushall returns the number of open streams (input and output). There is no error return.

Remarks

By default, the _flushall function writes to appropriate files the contents of all buffers associated with open output streams. All buffers associated with open input streams are cleared of their current contents. (These 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 streams.)

If a read follows a call to _flushall, new data is read from the input files into the buffers. All streams remain open after the call to _flushall.

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.

Requirements

Function	Required header
_flushall	<stdio.h>

For more compatibility information, see Compatibility in the Introduction.

Example

// crt_flushall.c  
// This program uses _flushall  
// to flush all open buffers.  
  
#include <stdio.h>  
  
int main( void )  
{  
   int numflushed;  
  
   numflushed = _flushall();  
   printf( "There were %d streams flushed\n", numflushed );  
}  

There were 3 streams flushed  

See Also

Stream I/O
_commit
fclose, _fcloseall
fflush
setvbuf