Lazarus Pascal - Quicksort an Array of string, by the length of the strings - Delphi, Lazarus, Free Pascal https://www.tweaking4all.com/forum/delphi-lazarus-free-pascal/lazarus-pascal-quicksort-an-array-of-string-by-the-length-of-the-strings/ Tweaking4All.com Discussion Board en-US Tue, 21 Jul 2026 01:53:53 +0000 wpForo 60 Lazarus Pascal - Quicksort an Array of string, by the length of the strings https://www.tweaking4all.com/forum/delphi-lazarus-free-pascal/lazarus-pascal-quicksort-an-array-of-string-by-the-length-of-the-strings/#post-6142 Fri, 10 Oct 2025 16:46:51 +0000 Had to write a procedure that sorts an array of strings (dynamic) by the length of the individual strings.
Thought someone may find this useful:

// QuickSort array of string by string length
procedure QuickSortByLength(ListOfStrings: array of string; Start: integer = -1; Stop: Integer = -1);
var
  i, j, PivotLen: Integer;
  Pivot: string;
  Temp: string;
begin
  if (Start=-1) or (Stop=-1) then
    begin
      Start := 0;
      Stop  := Length(ListOfStrings)-1;
    end;

  i := Start;
  j := Stop;
  Pivot := ListOfStrings;
  PivotLen := Length(Pivot);

  repeat
    while Length(ListOfStrings) < PivotLen do Inc(i);
    while Length(ListOfStrings) > PivotLen do Dec(j);

    if i <= j then
      begin
        Temp := ListOfStrings;
        ListOfStrings := ListOfStrings;
        ListOfStrings := Temp;
        Inc(i);
        Dec(j);
      end;
  until i > j;

  if Start < j then QuickSortByLength(ListOfStrings, Start, j);
  if i < Stop then QuickSortByLength(ListOfStrings, i, Stop);
end;

I did write it so that when you pass only an array, it will sort the entire array.

Calling this function:

...
var
   MyStrings : array of string;
...

// sort entire list automatically
QuickSortByLength(MyStrings);
...

// sort entire list manually
QuickSortByLength(MyStrings, 0, length(MyStrings)-1);
...

// sort only a section
QuickSortByLength(MyStrings, 5, 10);
...

 

]]> Delphi, Lazarus, Free Pascal Hans https://www.tweaking4all.com/forum/delphi-lazarus-free-pascal/lazarus-pascal-quicksort-an-array-of-string-by-the-length-of-the-strings/#post-6142