[jorge82]

Hola, a ver si te sirve esto:

Código Delphi [-]
function Buscar(const S1, S2: string): string;
var
  I, J: Integer;
  STemp: string;
begin
  Result := '';
  for I := 1 to Length(S1) do
  begin
    for J := 1 to Length(S2) do
    begin
      if (S1[i] = S2[J]) then
      begin
        STemp := UpperCase(S1[i]);
        Break;
      end
      else
        STemp := S1[i];
    end;
    Result := Result + STemp;
  end;
end;