Replace final occurance of a substring

[mathgod]

I am drawing a blank on this one and I think the solution will be simple. I know how to replace the first occurrence of a substring by using the pos function but how do I replace the final occurrence of a substring? There must be a more efficient way to do this than reversing the string values.

[Kambiz]

The following function works like Pos function except that it begins the search from end of string.

Code: Select all

function RPos(const SubStr, Str: String): Integer;
var
  I, X: Integer;
  LenSubStr: Integer;
begin
  I := Length(Str);
  LenSubStr := Length(SubStr);
  while I >= LenSubStr do
  begin
    if Str[I] = SubStr[LenSubStr] then
    begin
      X := 1;
      while (X < LenSubStr) and (Str[I - X] = SubStr[LenSubStr - X]) do
        Inc(X);
      if X = LenSubStr then
      begin
        Result := I - LenSubStr + 1;
        Exit;
      end;
    end;
    Dec(I);
  end;
  Result := 0;
end;


[mathgod]

Thank you, Kambiz.