TStringList.CustomSort implementation

[Ronan]

Dear All,

I'm trying to implement the CustomSort in TstringList class, with another more efficient sorting algorithm but I'm unable to do so .

// The code declaration is as follow

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function CompareFloat(List: TStringList; Index1, Index2: Integer): Integer;

Code implementation and embedding it into CustomSort as callback function raises the following erros described below

Code: [Select]

var
   SL :TstringList;
SL.CustomSort(CompareFloat);
//SL.CustomSort(@CompareFloat); // Tried this one also
The first function call 'SL.CustomSort(CompareFloat)' retrieves that error from compiler "Error: Wrong number of parameters specified for call to "CompareFloat"

Second function call 'SL.CustomSort(@CompareFloat)' retrieves that error from compiler Error: Only class methods can be referred with class references

Regards,

[howardpc]

The first syntax without "@" indicates that you are in {$mode objfpc} so the address-of operator is required when referencing procedural types.

The second error may mean your sl.Customsort(@...) call is not within a normal

Code: [Select]

begin
...
end;
block as part of 'ordinary' code within a method somewhere (the snippet you give shows the call coming immediately after a var declaration - not sure if this is an exact copy of your code or not).

[Ronan]

Thank you in advance,
original code is as shown below, in any case that issue is solved by setting the mode to delphi,

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SL :TStringList;
 str :string;
 i:Integer;
begin
  SL := TStringList.Create;
  SL.Add('8.3875');
  SL.Add('10.456');
  SL.Add('100');
  SL.Add('15');
  SL.Add('0.005');

  SL.CustomSort(CompareFloat);

Another question arises in mind related with the operation of CustomSort function, what the index1 and index2 indicates in function

Code: [Select]

CompareFloat(List: TStringList; Index1, Index2: Integer): Integer; are those two indices subsequent pointer to the list content?

Regards,

[Leledumbo]

Another question arises in mind related with the operation of CustomSort function, what the index1 and index2 indicates in function

Code: [Select]

CompareFloat(List: TStringList; Index1, Index2: Integer): Integer; are those two indices subsequent pointer to the list content?

http://www.freepascal.org/docs-html/rtl/classes/tstringlist.customsort.html[