Remove lines from a file: Difference between revisions

=={{header|PureBasic}}==

<lang PureBasic>

; Contents of file 'input.txt' before deletion of lines :

;

; cat

; dog

; giraffe

; lion

; mouse

; pig

; tiger

; zebra

EnableExplicit

#Output$ = "output.txt"; insert path to temporary output file

Procedure RemoveLines(Input$, StartLine, NbLines)

Protected lineCount = 0

Protected endline = StartLine + NbLines - 1

Protected row$

If Not ReadFile(0, Input$)

PrintN("Error opening input file")

ProcedureReturn

EndIf

If Not CreateFile(1, #Output$)

PrintN("Error creating output file")

CloseFile(0)

ProcedureReturn

EndIf

While Not Eof(0)

row$ = ReadString(0)

lineCount + 1

If lineCount < StartLine Or lineCount > endLine

WriteStringN(1, row$)

EndIf

Wend

If endLine > lineCount

PrintN("Attempted to remove lines beyond the end of the file")

; but still allow removal of lines (if any) up to the end of the file

EndIf

CloseFile(0)

CloseFile(1)

If Not DeleteFile(Input$)

PrintN("Unable to delete input file so output file can be renamed")

ProcedureReturn

EndIf

If Not RenameFile(#Output$, Input$)

PrintN("Unable to rename output file")

EndIf

EndProcedure

Define fInput$

If OpenConsole()

; delete lines 2,3 amnd 4 of 'input.txt'

fInput$ = "input.txt"; insert path to input file

RemoveLines(fInput$, 2, 3)

PrintN("")

PrintN("Press any key to close the console")

Repeat: Delay(10) : Until Inkey() <> ""

CloseConsole()

EndIf

</lang>

{{out|Output ('input.txt' after removal of lines}}

<pre>

cat

mouse

pig

tiger

zebra

</pre>