How to Open a File for Both Read and Write?

[Zohar]

Hi

If I open a File like this:

Local $hFile =FileOpen($FilePath,0) ;0=Read
  $String_FileContent =FileRead($hFile)
FileClose($hFile)

Then I am able to successfully read the file.

If I open a File like this:

Local $hFile =FileOpen($FilePath,2) ;2=Write
  FileWrite($hFile,$String_FileContent)
FileClose($hFile)

Then I am able to successfully write to the file.

But what If I want to do both Read+Write in 1 FileOpen+Close?

How do I FileOpen() a file for both Read+Write?

When I try

Local $hFile =FileOpen($FilePath,2) ;2=Write
  $String_FileContent =FileRead($hFile)
FileClose($hFile)

Msg($String_FileContent)

The messagebox shows an empty string..

As If When FileOpen() with mode=2, then you can't Read from the file, only Write to it.

What should I do?

Edited July 5, 2012 by Zohar

[JohnQSmith]

Mode 2 erases the previous contents of the file so there is nothing to read.

Edit: Use mode 1.

From the help...

1 = Write mode (append to end of file)

2 = Write mode (erase previous contents)

also from the help...

When reading and writing via the same file handle, the FileSetPos() function must be used to update the current file position.

Edit 2: Added link to FileSetPos()

Edited July 5, 2012 by JohnQSmith

[Zohar]

Hi

Regarding "1 = Write mode (append to end of file)",

The help file doesn't say it can be used for both Read+Write.

But I'll try it now, thank you.

[Melba23]

Zohar,

Mode 2 erases the current file contents (as explained in the Help file). However, Mode 1 will only append to the file (again as explained in the Help file).

So you may need to use 2 FileOpen/Close cycles depending on what you want to do with the content - a single call might not be possible.

M23

[Zohar]

JohnQSmith:

FileOpen() with mode=1 yielded the same result:

FileRead() returns an Empty String..

Melba23:

No way to do it in 1 FileOpen() at all? :/

Edited July 5, 2012 by Zohar

[JohnQSmith]

Regarding "1 = Write mode (append to end of file)",

Don't forget the FileSetPos() otherwise the position pointer in the file will be at the end of the file on open (hence the "append") and there will be nothing to read.

Edit: So, if you wanted to read from the beginning of the file after opening it, you would need to add the following before your FileRead() command.

FileSetPos( $hFile, 0, 0 )

Edited July 5, 2012 by JohnQSmith

[Zohar]

JohnQSmith:

FileGetPos($hFile) returns 0, and not EOF..

But even If I do what you recommend:

FileSetPos($hFile,0,0)

I still get an empty string from FileRead()

[BrewManNH]

Did you open the file for reading?

[JohnQSmith]

Umm... are you sure there's actually something in the file? If the file is empty, there is nothing to read.

Edit: I just tried it, and it works fine for me (using a file with text in it)...

$theFile = FileOpen("README.TXT", 1)
FileSetPos($theFile,0,0)
ConsoleWrite(FileRead($theFile))
FileClose($theFile)

Edited July 5, 2012 by JohnQSmith

[Melba23]

Zohar,

Try this:

$hFile = FileOpen(@ScriptFullPath, 1)

FileSetPos($hFile, 0, 0)
$sText = FileRead($hFile)
MsgBox(0, "Content", $sText)

FileWrite($hFile, @CRLF & @CRLF & "New Stuff")

FileSetPos($hFile, 0, 0)
$sText = FileRead($hFile)
MsgBox(0, "Content", $sText)

FileClose($hFile)

Is that what you wanted?

M23

[Zohar]

Umm... are you sure there's actually something in the file? If the file is empty, there is nothing to read.

You are right!

The file's content was deleted by one of the earlier FileOpen(mode=2).

Once I fixed that, FileOpen(mode=1) works!!!

Thank you very much

Edited July 5, 2012 by Zohar

[Zohar]

BTW,

Did you notice that in the helpfile, in FileOpen(), mode=4 is missing?

What is mode=4?

Edited July 5, 2012 by Zohar

[BrewManNH]

I don't believe there is a mode 4.

[GEOSoft]

Mode to open the file in.

Can be a combination of the following:

0 = Read mode (default)

1 = Write mode (append to end of file)

2 = Write mode (erase previous contents)

8 = Create directory structure if it doesn't exist (See Remarks).

16 = Force binary mode (See Remarks).

32 = Use Unicode UTF16 Little Endian reading and writing mode. Reading does not override existing BOM.

64 = Use Unicode UTF16 Big Endian reading and writing mode. Reading does not override existing BOM.

128 = Use Unicode UTF8 (with BOM) reading and writing mode. Reading does not override existing BOM.

256 = Use Unicode UTF8 (without BOM) reading and writing mode.

16384 = When opening for reading and no BOM is present, use full file UTF8 detection. If this is not used then only the initial part of the file is checked for UTF8.

The folder path must already exist (except using mode '8' - See Remarks).

Do you see anything in there that adds up to 4?

That having been said; the text I just quoted needs looking at.

Can be a combination of the following:

is technically incorrect. As far as I am aware you can not combine 0, 1, 2.

It should probably read something like

0, 1 or 2 can be combined with the following:

but that could be considered as nit picking.

EDIT:

BTW: You don't need to use FileOpen/FileClose at all for a simple FileRead() operation. Just FileRead() it to a variable, work on the variable and then write it back using FileOpen()/FileWrite()/FileClose() so you can set the write mode.

Edited July 5, 2012 by GEOSoft