FileReadLine - can you read second last line?

[Malkey]

Here are another couple of methods to return individual lines from the end of a file.

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Local $sFile = "test.txt"
; http://www.autoitscript.com/forum/topic/143295-filereadline-can-you-read-second-last-line/page__st__20#entry1009431

ConsoleWrite(@LF & "===== File Name ======================================" & @LF)
ConsoleWrite("The first line      > " & _FileReadLine($sFile) & @LF) ; Returns first line.
ConsoleWrite("The first line      > " & _FileReadLine($sFile, "") & @LF) ; Returns first line (file handle not used).
ConsoleWrite("The last line    > " & _FileReadLine($sFile, -1) & @LF) ; Returns last line.
ConsoleWrite("The penultimate line> " & _FileReadLine($sFile, -2) & @LF) ; Returns penultimate line.
ConsoleWrite("The third last line > " & _FileReadLine($sFile, -3) & @LF) ; Returns third last line.

ConsoleWrite(@LF & "===== File handle ==================================" & @LF)
Local $file = FileOpen($sFile, 0)

ConsoleWrite("The first line      > " & _FileReadLine($file) & @LF) ; Returns first line.
ConsoleWrite("The second line    > " & _FileReadLine($file, "") & @LF) ; Returns first line (file handle not used).
ConsoleWrite("The last line    > " & _FileReadLine($file, -1) & @LF) ; Returns last line.
ConsoleWrite("The penultimate line> " & _FileReadLine($file, -2) & @LF) ; Returns penultimate line.
ConsoleWrite("The third last line > " & _FileReadLine($file, -3) & @LF) ; Returns third last line.

FileClose($file)

ConsoleWrite(@LF & "=== 2 StringInStrs =====================================" & @LF)
ConsoleWrite("The last line    > " & _FileReadEndLine($sFile, -1) & @LF) ; Returns last line.
ConsoleWrite("The penultimate line> " & _FileReadEndLine($sFile, -2) & @LF) ; Returns penultimate line.
ConsoleWrite("The third last line > " & _FileReadEndLine($sFile, -3) & @LF) ; Returns third last line.

Local $s = FileRead($sFile)
If StringRegExp($s, "v$") = 0 Then $s &= @LF
ConsoleWrite(@LF & 'Three-liner RegExp returns the penultimate line> "' & _
        StringRegExpReplace( $s, "^(V*R)+(V*)((V*R){2})", "2") & '"' & @LF)


Func _FileReadLine($sFile, $iLine = "")
    If $iLine = "" Or $iLine = Default Then ; Successive calls with these parameters increments line number, only when used in conjunction with a file handle.
        Return FileReadLine($sFile)
    ElseIf $iLine < -1 Then
        FileSetPos($sFile, 0, 0);$FILE_BEGIN = 0 from FileConstants.au3 and NOT from Constants.au3 as help file says.
        Local $s = FileRead($sFile)
        If StringRegExp($s, "v$") = 0 Then $s &= @LF
        Return StringRegExpReplace($s, "^(V*R)+(V*)((V*R){" & (-1 * $iLine) & "})$", "2")
    Else
        Return FileReadLine($sFile, $iLine)
    EndIf
EndFunc   ;==>_FileReadLine

Func _FileReadEndLine($sFile, $iLine = -1)
    Local $s = FileRead($sFile)
    If StringRegExp($s, "v$") = 0 Then $iLine += 1
    Local $Fst = StringInStr($s, @LF, 2, $iLine - 1) + 1
    Return StringMid($s, $Fst, (StringInStr($s, @LF, 2, $iLine)) - $Fst)
EndFunc   ;==>_FileReadEndLine

Edit: Adjusted script so that correct results are returned when there is also no trailing linefeed in file.

Edited August 14, 2012 by Malkey

[guinness]

$FILE_BEGIN is in Constants.au3 as FileConstants.au3 is included.

[AZJIO]

#include <FileConstants.au3>
$Pos = 200

$hFile = FileOpen(@ScriptFullPath)

FileSetPos($hFile, -$Pos, $FILE_END)
$sText = FileRead($hFile)
FileClose($hFile)

While 1
    $string = _ReadString($Pos)
    MsgBox(0, '', $string)
    ; ClipPut($string)
    If $Pos<1 Then ExitLoop
WEnd

Func _ReadString(ByRef $Pos)
    $TmpPos = StringInStr($sText, @CRLF, 0, -1, $Pos, $Pos)
    $string = StringMid($sText, $TmpPos + 2, $Pos - $TmpPos - 2)
    $Pos = $TmpPos
    Return $string
EndFunc

Edited May 8, 2013 by AZJIO

[UEZ]

Here another one

#include <File.au3>
$sFile = @ScriptDir & "Testfile.txt"
$hFile = FileOpen($sFile, 2)
Global $sTxt
For $i = 1 To $iLines
    $sTxt &= "Line number " & $i & @CRLF
Next
FileWrite($hFile, $sTxt)
FileClose($hFile)

MsgBox(0, "Test", GetLineContent($sFile, _FileCountLines($sFile) - 1))


Func GetLineContent($sFile, $iLineNum)
 Return StringRegExpReplace(FileRead($sFile), "^(.*v+?|$){" & $iLineNum & "}(?s).*", "$1")
EndFunc

Br,

UEZ

Edited August 14, 2012 by UEZ

[AZJIO]

Here another one

When row 30000 returns all of the text.

My version is faster than StringSplit, if many rows. But it is impossible to obtain the specified string, only the follow-

[UEZ]

I never tested it with huge lines!

Anyway, when I run this I get an error: AutoIT3.exe ended.rc:-1073741571 (0xC00000FD).

#include <File.au3>
$sFile = @ScriptDir & "Testfile.txt"

$iLines = 3957 ;3957 - 4096 is crashing the script and above 4096 the whole string will be displayed
$hFile = FileOpen($sFile, 2)
Global $sTxt
For $i = 1 To $iLines
    $sTxt &= "Line number " & $i & @CRLF
Next
FileWrite($hFile, $sTxt)
FileClose($hFile)

$hFile = FileOpen($sFile)
$sString = FileRead($hFile)
FileClose($hFile)

MsgBox(0, "Test", GetLineContent($sString, $iLines - 1))

Func GetLineContent($sString, $iLineNum)
    Return StringRegExpReplace($sString, "^(.*v+?|$){" & $iLineNum & "}(?s).*", "$1")
EndFunc

$iLines from 3957 up to 4096 is crashing the script and above 4096 returns the whole string. Strange.

Seems to be a problem with StringRegExpReplace() and the iLineNum value. {x} seems to be limited to 3956.

Edit: {x} has a limited recursion stack which runs out of stack and crashes when the limit is reached!

Nice to have a one liner but not working properly for larger than 3956 lines So better forget this idea!

Br,

UEZ

Edited August 14, 2012 by UEZ

[kiffab]

Hi GUys

Thanks for all the great feedback. What i've done works but I also have all these options available to me.

So... which is the best? ;-)

Oh, and regarding my earlier question re event logs - I am still using my batch file method but with a string at the end of the file which must be present for my function to continue.

[Biatu]

On 8/14/2012 at 10:29 AM, UEZ said:

I never tested it with huge lines!

 

Anyway, when I run this I get an error: AutoIT3.exe ended.rc:-1073741571 (0xC00000FD).

 

 

#include <File.au3>
$sFile = @ScriptDir & "Testfile.txt"

$iLines = 3957 ;3957 - 4096 is crashing the script and above 4096 the whole string will be displayed
$hFile = FileOpen($sFile, 2)
Global $sTxt
For $i = 1 To $iLines
    $sTxt &= "Line number " & $i & @CRLF
Next
FileWrite($hFile, $sTxt)
FileClose($hFile)

$hFile = FileOpen($sFile)
$sString = FileRead($hFile)
FileClose($hFile)

MsgBox(0, "Test", GetLineContent($sString, $iLines - 1))

Func GetLineContent($sString, $iLineNum)
    Return StringRegExpReplace($sString, "^(.*v+?|$){" & $iLineNum & "}(?s).*", "$1")
EndFunc

 

$iLines from 3957 up to 4096 is crashing the script and above 4096 returns the whole string. Strange.

 

Seems to be a problem with StringRegExpReplace() and the iLineNum value. {x} seems to be limited to 3956.

 

 

Edit: {x} has a limited recursion stack which runs out of stack and crashes when the limit is reached!

Nice to have a one liner but not working properly for larger than 3956 lines So better forget this idea!

 

 

 

Br,

UEZ

Exactly, as in the first post, the best solution is for big files, sometimes exceeding the AutoIt memory limits. So anything that Reads the whole file is not perferred, such as ReadFile($hFile) or _FileReadToArray()

 

On page 1 water already posted what looks like the best solution, and the fastest?

Edited January 29, 2017 by Biatu