Delphi CustomSort with Numbers and Letters [closed]

Question

This question is unlikely to help any future visitors; it is only relevant to a small geographic area, a specific moment in time, or an extraordinarily narrow situation that is not generally applicable to the worldwide audience of the internet. For help making this question more broadly applicable, visit the help center.

Closed 9 years ago.

Delphi used: 2007

Hello,

I have a Listview with several columns. I want to sort one specific column. Items can be numbers or letters.

Basically, the order should be the following: 1->99, A->Z, AA->ZZ, AAA->ZZZ. I found some CustomSort code on the Internet and I modified it. Here's the result (well, the code is bigger, but I'm only putting what's important):

function CustomSortProc(Item1, Item2: TListItem; SortColumn: Integer): Integer; stdcall;
var
 s1, s2: string;
 i1, i2: Integer;
 r1, r2: Boolean;

 function IsValidNumber(AString : string; var AInteger : Integer): Boolean;
 var
  Code: Integer;
 begin
  Val(AString, AInteger, Code);
  Result := (Code = 0);
 end;

 function CompareNumeric(AInt1, AInt2: Integer): Integer;
 begin
  if AInt1 > AInt2 then Result := 1 else
  if AInt1 = AInt2 then Result := 0 else Result := -1;
 end;

begin
 Result := 0;

 if (Item1 = nil) or (Item2 = nil) then Exit;

 r1 := IsValidNumber(s1, i1);
 r2 := IsValidNumber(s2, i2);
 Result := ord(r1 or r2);
 if Result <> 0 then Result := CompareNumeric(i1, i2) else
 begin
  Result := Length(s1) - Length(s2);
  if Result = 0 then Result := lstrcmp(PChar(s1), PChar(s2));
 end;
end;

And here's how the column is sorted:

In other words, the letters and the numbers are correctly sorted. However, I am unable to put all the numbers before the letters. I'm sure it's something simple, but I cannot for the life of me figure it out.

Thank you very much.

Answer 1

If one is a string and one is an int, the value of the string from val is 0 so it will before.

if (Item1 = nil) or (Item2 = nil) then Exit;

 r1 := IsValidNumber(s1, i1);
 r2 := IsValidNumber(s2, i2);
 if (r1 and r2) then
   Result := CompareNumeric(i1, i2)
 else
   if r1 then 
     result := -1
   else
    if r2 then
      result := 1
    else
    begin
     Result := Length(s1) - Length(s2);
     if Result = 0 then 
       Result := lstrcmp(PChar(s1), PChar(s2));
    end;
end;

I think, no Dephi on the machine to check.