Call 'path\fileio.kxf'

$File = 'path\filename.txt'           ; specify your source file

$aFileData = FileIO($File, 'R')       ; load the UDF from the correct path, or copy/paste it here instead

; enumerate the data to find the longest line - unnecessary if you want all at a known fixed length
$Longest = 0
For $R = 0 to UBound($aFileData)
  $L = Len($aFileData[$R]
  If $L > $Longest $Longest = $L EndIf
Next

; Create a "pad string"
$Pad = ''
For $R = 1 to $Longest
  $Pad = $Pad + ' '
Next

; Pad the array values to the desired length
For $R = 0 to UBound($aFileData)
  $aFileData[$R] = Left($aFileData + $Pad, $Longest)
Next

; Write the file data back
$aFileData = FileIO($File, 'W', $aFileData)

; done
Exit 0