Read multiple times

[Digisoul]

Hello guys,

I want to know that how can i read any opend file multiple times.

i wrote some exapmles wich explane my problem more clear

1st: example

Global $f= FileOpen('e:\games\nfs7.exe',16); file size is 178 MB
Global $data = FileRead($f)

$read1 = read(987)
MsgBox(0,"512",$read1)
$read2= read(256)
MsgBox(0,"256",$read2)

Func read($bytes)
Switch $bytes
    Case 0
        Return $data
    Case Else
        Return StringMid($data,1,$bytes)
EndSwitch   
EndFunc

This example works gr8 with small files but not work for huge file, actualy wen i run this code my prog will freez

2nd: example

global $f= FileOpen('e:\games\nfs7.exe',16); file size is 178 MB

$read1 = read(987)
MsgBox(0,"512",$read1)
$read2= read(256)
MsgBox(0,"256",$read2)

Func read($bytes)
Switch $bytes
    Case 0
        Return FileRead($f)
    Case Else
        Return fileread($f,$bytes)
EndSwitch   
EndFunc

This code give me the quick result but wen i call read function for $read2 it will cut the data that i call for $read1.

and never shows the data frm 1st byte.

i want something like; when will i call the read function it returns the data from the 1st byte.

so plz help me.

thanks in advance for your kind help.

Edited December 11, 2008 by Digisoul

[PsaltyDS]

Hello guys,

I want to know that how can i read any opend file multiple times.

i wrote some exapmles wich explane my problem more clear

1st: example

Global $f= FileOpen('e:\games\nfs7.exe',16); file size is 178 MB
Global $data = FileRead($f)

$read1 = read(987)
MsgBox(0,"512",$read1)
$read2= read(256)
MsgBox(0,"256",$read2)

Func read($bytes)
Switch $bytes
    Case 0
        Return $data
    Case Else
        Return StringMid($data,1,$bytes)
EndSwitch   
EndFunc

This example works gr8 with small files but not work for huge file, actualy wen i run this code my prog will freez

2nd: example

global $f= FileOpen('e:\games\nfs7.exe',16); file size is 178 MB

$read1 = read(987)
MsgBox(0,"512",$read1)
$read2= read(256)
MsgBox(0,"256",$read2)

Func read($bytes)
Switch $bytes
    Case 0
        Return FileRead($f)
    Case Else
        Return fileread($f,$bytes)
EndSwitch   
EndFunc

This code give me the quick result but wen i call read function for $read2 it will cut the data that i call for $read1.

and never shows the data frm 1st byte.

i want something like; when will i call the read function it returns the data from the 1st byte.

so plz help me.

thanks in advance for your kind help.

Although AutoIt allows a single variable to be up to 2GB in length, the practical limit imposed by the Win32 environment (maybe no in Win64?) limits you to more like 128MB in real use.

You can read the file in parts, as each call to FileRead() increments the pointer of what gets read next. This is why your $read2 is the next data AFTER what you got in $read1.

You can modify this pointer to read a specific part of the file using _WinAPI_ReadFile(). Make sure you have the latest Beta downloaded and check it out in the Beta help file.

[Digisoul]

Although AutoIt allows a single variable to be up to 2GB in length, the practical limit imposed by the Win32 environment (maybe no in Win64?) limits you to more like 128MB in real use.

You can read the file in parts, as each call to FileRead() increments the pointer of what gets read next. This is why your $read2 is the next data AFTER what you got in $read1.

You can modify this pointer to read a specific part of the file using _WinAPI_ReadFile(). Make sure you have the latest Beta downloaded and check it out in the Beta help file.

Thank you PsaltyDS.

i tried with this but the result was same as that i mentioned in example 1 in my 1st post.

#include <WINAPI.au3>
Global $f,$sz,$bBuffer,$BufferSize = 2048
$sz = FileGetSize('e:\games\nfs7.exe')
$bBuffer = DllStructCreate("byte[" & $sz & "]")
$f = _WinAPI_CreateFile('e:\games\nfs7.exe', 2, 2)


$read1 = read(987)
MsgBox(0,"512",$read1)
$read2= read(256)
MsgBox(0,"Full",$read2)

Func read($bytes)
_WinAPI_SetFilePointer($f, 0)
Switch $bytes
    Case 0
        $read=_WinAPI_ReadFile($f, DllStructGetPtr($bBuffer), $sz, $sz)
        if $read <> false Then Return DllStructGetData($bBuffer, 1)
    Case Else
        $read=_WinAPI_ReadFile($f, DllStructGetPtr($bBuffer), $BufferSize, $bytes)
        if $read <> false Then Return DllStructGetData($bBuffer, 1)
EndSwitch   
EndFunc
                    
Func _WinAPI_SetFilePointer($hFile, $nDistance, $nMethod = 0)
Local $nRet
$nRet = DllCall("kernel32.dll", "dword", "SetFilePointer", "ptr", $hFile, "long", $nDistance, "ptr", 0, "dword", $nMethod)
Return $nRet[0]
EndFunc

please help me to improve this code

[ChangMinYang]

Try to "MsVcrt.dll"'s fopen

Search Expression = fsetpos + fread