Page 1 of 1
Forum

Welcome to the Tweaking4All community forums!
When participating, please keep the Forum Rules in mind!

Topics for particular software or systems: Start your topic link with the name of the application or system.
For example “MacOS X – Your question“, or “MS Word – Your Tip or Trick“.

Please note that switching to another language when reading a post will not bring you to the same post, in Dutch, as there is no translation for that post!




Share:
Notifications
Clear all

[Solved] Lazarus Pascal - QuickSort TStringList to QuickSort Array of Records

1 Posts
1 Users
0 Likes
4,447 Views
 Hans
(@hans)
Famed Member Admin
Joined: 11 years ago
Posts: 2660
Topic starter  

I ran into this very nice looking code for a QuickSort routine in Lazarus Pascal:

procedure QuickSort(var A: TStringList);
  procedure Sort(L, R: Integer);
  var
    I, J: Integer;
    Y, X:string;
  begin
    I:= L; J:= R; X:= A[(L+R) DIV 2];
    repeat
      while StrIcomp(pchar(A),pchar(X))<0 do inc(I);
      while StrIComp(pchar(X),pchar(A[J]))<0 do dec(J); 
      if I <= J then
      begin
        Y:= A; A:= A[J]; A[J]:= Y;
        inc(I); dec(J);
      end;
    until I > J;
    if L < J then Sort(L,J);
    if I < R then Sort(I,R);
  end;
begin
  Sort(0,A.Count-1);
end;

It's written to sort a TStringList and called as such:

QuickSort(MyStringList);

Unfortunately, this is not what I needed.
I wanted to sort an array of records.

So below my adapted version of this code for an array:

TSomeLanguage = record
    abbreviation: string;
    name: string;
    englishName: string;
  end;
...
SomeLanguages : array of TSomeLanguage;
...
procedure TNMTVForm.QuickSortLanguages(var A: array of TSomeLanguage);
    procedure Sort(L, R: Integer);
    var
      I, J: Integer;
      Y, X: TTVDBSeries;
    begin
      I:= L; J:= R; X:= A[(L+R) DIV 2];
      repeat
        while StrIcomp(pchar(A.englishName),pchar(X.englishName))<0 do inc(I); // <-- adapt to your array
        while StrIComp(pchar(X.englishName),pchar(A[J].englishName))<0 do dec(J); // <-- adapt to your array 
        if I <= J then
        begin
          Y:= A; A:= A[J]; A[J]:= Y;
          inc(I); dec(J);
        end;
      until I > J;
      if L < J then Sort(L,J);
      if I < R then Sort(I,R);
    end;
begin
  Sort(0,length(A)-1);
end;

...

QuickSortLanguages(SomeLanguages);

...

This will sort the array "SomeLanguages" based on the field "englishName".
You can see the 2 lines in the code which you may have to alter for the array you'd defined.

Hope this is helpful for anyone looking to sort their arrays ... 


   
ReplyQuote

Like what you see and you'd like to help out? 

The best way to help is of course by assisting others with their questions here in the forum, but you can also help us out in other ways:

- Do your shopping at Amazon, it will not cost you anything extra but may generate a small commission for us,
- send a cup of coffee through PayPal ($5, $10, $20, or custom amount),
- become a Patreon,
- donate BitCoin (BTC), or BitCoinCash (BCH).

Share: