Display each line from a file on a statusbar by keypress iniated by a toolbar button.

That's not a good idea to do it by re-reading each line until you find the one needed. besides, there is missing something on this algo to work :
do
  readln(f,s);
  inc(i);
end;
and line should not be a global variable but a parameter.

I would strongly recommend the use of TStringList :
- you create your list object once only (by the main form)
- you destroy it at the detruction of the form
- at some point, you read your while file into it
- and you access it line by line at will.

TForm1= class(TForm)
...
private
  _MyStrList:TStringList;
...
end;

procedure TForm1.FormCreate(Sender:TObject);
begin
  _MyStrList:=TStringList.Create;
...
end;

procedure TForm1.FormDestroy(Sender:TObject);
begin
  _MyStrList.Free;
...
end;

procedure TForm1.LoadFile(filename:string);
begin
 _MyStrList.LoadFromFile(filename);
// maybe something like _Line:=0; to reset position when loading a new file
end;

then, instead of calling your getNextLine, you simply use _MyStrList[_Line] to get the line n°_Line
You can test for _MyStrList.Count before, to avoid error

function TForm1.get(L:integer):string;
begin
 if (L>=0) And (L<_MyStrList.Count)
   Then Result:=_MyStrList[L]
   Else Result:='';
end;

the last function 'get' should be called something like 'getLine' .

you allready this question:
https://www.experts-exchange.com/questions/21849969/A-tstringlist-question.html

and you have pulled "line: integer = 0;" out of it's context

personally i don't see any use whatsoever to read a text line using the statusbar
so why do you wanna do that, what's the point ?

and don't come around saying you don't want to use TActionList
this is the easiest way to use shortcut keys
without have to hassle around yourself with keypreview

use F5-F6 alternatively to go up or down the file after loading

--dfm--

object Form1: TForm1
  Left = 0
  Top = 0
  Caption = 'frmFileOnStatusbar'
  ClientHeight = 426
  ClientWidth = 937
  Color = clBtnFace
  Font.Charset = DEFAULT_CHARSET
  Font.Color = clWindowText
  Font.Height = -11
  Font.Name = 'Tahoma'
  Font.Style = []
  KeyPreview = True
  OldCreateOrder = False
  OnKeyDown = FormKeyDown
  PixelsPerInch = 96
  TextHeight = 13
  object sbFile: TStatusBar
    Left = 0
    Top = 407
    Width = 937
    Height = 19
    Panels = <
      item
        Text = 'Line'
        Width = 70
      end
      item
        Width = 50
      end>
  end
  object btnLoadFile: TButton
    Left = 48
    Top = 39
    Width = 75
    Height = 25
    Caption = 'Load File'
    TabOrder = 1
    OnClick = btnLoadFileClick
  end
  object Memo1: TMemo
    Left = 480
    Top = 8
    Width = 257
    Height = 361
    Lines.Strings = (
      'Memo1')
    TabOrder = 2
  end
  object odFile: TOpenDialog
    Filter = 'All files|*.*'
    Title = 'Open file'
    Left = 256
    Top = 24
  end
  object alKeys: TActionList
    Left = 376
    Top = 8
    object actKeyUp: TAction
      Caption = 'Key Up'
      ShortCut = 116
      OnExecute = actKeyUpExecute
    end
    object actKeyDown: TAction
      Caption = 'KeyDown'
      ShortCut = 117
      OnExecute = actKeyDownExecute
    end
  end
end

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>> you like underscores a lot don't you ?
yes, I use it where almost everybody else use f to state it is a private variable. I find it easier to read and never quite understood why f stands for... so if you can explain it to me, I might not change my habits but out of curiosity I would be glad

f stands for field
i'd need to search where that's stated

some delphi code in the beginning had m for method too,
but that was dropped soon

Thanx, Peter kiers