rsegal
23rd March 2005 21:27 UTC

Reading a file in reverse
So I've got a text file I want to read in reverse line by line which I believe I should be able to do using FileSeek however because I'm reading the file in reverse order how will I know when I've reached the beginning of the file? The end of the file has the EOF marker does the start have something similar?

Anders
24th March 2005 03:01 UTC

maybe not the best way to do it, but u could get the size of the file first, then store that in a var and decrease it when u call FileSeek

Instructor
24th March 2005 08:26 UTC

How you with FileSeek found start position of last line, for example (very interesting)?

Instructor
24th March 2005 12:00 UTC

Name "FileReadFromEnd"
OutFile "FileReadFromEnd.exe"

Function FileReadFromEnd
        Exch $0
        Push $1
        Push $2
        ClearErrors

        StrCpy $2 0
        FileOpen $0 $0 r
        IfErrors end
        FileRead $0 $1
        IfErrors +4
        Push $1
        IntOp $2 $2 + 1
        goto -4
        FileClose $0

        nextline:
        StrCmp $2 0 end
        IntOp $2 $2 - 1
        Pop $0
        IntOp $1 $2 + 1
        MessageBox MB_YESNO "$1-[$0]$\n$\nNext line?" IDYES nextline

        StrCmp $2 0 end
        IntOp $2 $2 - 1
        Pop $0
        StrCmp $2 0 0 -2

        end:
        Pop $2
        Pop $1
        Pop $0
FunctionEnd

Section
        Push "C:\File.txt"
        Call FileReadFromEnd
SectionEnd

Instructor
24th March 2005 21:06 UTC

I have completed function: "FileReadFromEnd" v1.0

rsegal
28th March 2005 16:49 UTC

Thanks for the feedback guys. I've been able to come up with a solution involving a few of the functions from the NSIS archive.