FileFlushfunction

Flush application stream buffers to system, or system buffers to file

Operating System Functionsfunctiondocumented

Syntax

Declare Function FileFlush ( ByVal filenum As Long = -1, ByVal systembuffers As Long = 0 ) As Long

Parameters

Name		Description
`filenum`		File number of bound file or device. If not given, or -1, then flush all open files.
`systembuffers`		If non-zero, flush system buffers to physical device. Default is zero (0).

Return value

Returns zero (0) for success or an error code if file buffers could not be flushed.

Description

FileFlush writes application buffered output to the underlying stream, and if systembuffers is non-zero, to the underlying physical device as well.

In the form FileFlush(filenum), the application output buffer for a specific file are written. And in the form FileFlush, all application buffers are written to the system. Typically, when a file is opened, the stream will be block buffered for binary and random files, and line buffered for append and output files. The FileFlush function overrides the normal buffering of the application and immediately writes buffered output to the system. The system may have it's own buffers as well.

In the form FileFlush(filenum,1), both the application buffer is flushed and the underlying system buffer is flushed to physical device. In the form FileFlush(,1), all application buffers are flushed and all underlying system buffers are flushed to physical device.

Remarks

Usage



#include "file.bi"

result = FileFlush()

result = FileFlush( filenum )

result = FileFlush( filenum, systembuffers )

Version

Since fbc 1.08.0

Differences from QB

New to FreeBASIC.

Example

#include "file.bi"



Dim As Long f1, f2

Dim As String s



Print "File length", "File string"



f1 = FreeFile

Open "fileflushtest.txt" For Output As #f1

Print #f1, "successful file flush"



f2 = FreeFile

Open "fileflushtest.txt" For Input As #f2

Line Input #f2, s

Print FileLen("fileflushtest.txt"), "'" & s & "'"  '' the string is not yet physically written to the file



FileFlush(f1)

Line Input #f2, s

Print FileLen("fileflushtest.txt"), "'" & s & "'"  '' the string is now physically written to the file



Close #f2

Close #f1



Sleep

Output (Windows):

File length   File string
 0            ''
 23           'successful file flush'

Reference

Documented in KeyPgFileflush.html