Reading a file in reverse

rsegalMarch 23, 2005 at 7:27 PM#

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?

AndersMarch 24, 2005 at 1:01 AM#

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

InstructorMarch 24, 2005 at 6:26 AM#

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

InstructorMarch 24, 2005 at 10:00 AM#edited March 24, 2005 at 10:20 AM

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

InstructorMarch 24, 2005 at 7:06 PM#

I have completed function: "FileReadFromEnd" v1.0

rsegalMarch 28, 2005 at 1:49 PM#

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.