FileSetEnd() - my example

[Zedna]

Because in AutoIt's helpfile there is very poor example for function FileSetEnd()

I add here for the reference my better example demonstrating expanding/truncating size of file also with retaining of original data.

Note: FileSetEnd() was added in AutoIt 3.3.13.11 (2014-07-27)

#include <FileConstants.au3>
#include <MsgBoxConstants.au3>

Example()

Func Example()
    Local Const $sFilePath = @TempDir & "\FileSetEnd.txt"

    ; create file 6 bytes in size
    FileDelete($sFilePath)
    FileWrite($sFilePath,'abc123')
    MsgBox($MB_SYSTEMMODAL, FileGetSize($sFilePath), FileRead($sFilePath)) ; 6 / abc123

    ; expand size of file to 9 bytes but don't write any data to expanded area
    $hFileOpen = FileOpen($sFilePath, $FO_APPEND)
    FileSetPos($hFileOpen, 9, $FILE_BEGIN)
    FileSetEnd($hFileOpen)
    FileClose($hFileOpen)
    MsgBox($MB_SYSTEMMODAL, FileGetSize($sFilePath), FileRead($sFilePath)) ; 9 / abc123

    ; write data to expanded area (more than size of expanded area) so size of file will auto expand to 12 bytes (6+6)
    $hFileOpen = FileOpen($sFilePath, $FO_APPEND)
    FileSetPos($hFileOpen, 6, $FILE_BEGIN)
    FileWrite($hFileOpen,'def456')
    FileClose($hFileOpen)
    MsgBox($MB_SYSTEMMODAL, FileGetSize($sFilePath), FileRead($sFilePath)) ; 12 / abc123def456

    ; truncate size of file to 9 bytes
    $hFileOpen = FileOpen($sFilePath, $FO_APPEND)
    FileSetPos($hFileOpen, 9, $FILE_BEGIN)
    FileSetEnd($hFileOpen)
    FileClose($hFileOpen)
    MsgBox($MB_SYSTEMMODAL, FileGetSize($sFilePath), FileRead($sFilePath)) ; 9 / abc123def

    FileDelete($sFilePath)
EndFunc   ;==>Example

Remarks:

- current position for FileSetEnd() can be changed by FileSetPos()

- for expanding/truncating of existing files with preserved content have to be used mode $FO_APPEND in FileOpen()

EDIT:

This my example in slightly changed version was added as example #2 to AutoIt's helpfile

in version 3.3.13.14 (2014-08-02).

Edited August 3, 2014 by Zedna

[guinness]

Because in AutoIt's helpfile is very poor example for function FileSetEnd()

If you wanted my attention all you had to do was send me a PM or create a Trac request.

[Zedna]

If you wanted my attention all you had to do was send me a PM or create a Trac request.

 

We had discussion about this here

You decided to not add my example and instead use your example which is by my opinion worse.

This is why I decided to add my example here to Example section on the forum for better future reference/searching.

[guinness]

I will have a look and amend according. 

[guinness]

I fail to see how your version is any "better", but I have added what I feel is an easy to understand example. Any problems please move to the private forum or PM me.

[Zedna]

This my example in slightly changed version was added as example #2 to AutoIt's helpfile

in version 3.3.13.14 (2014-08-02).