Alle nicht numerischen Zeichen aus String entfernen

[shmia]

Kopiert aus der JCL, Unit JclStrings:

Delphi-Quellcode:

function StrKeepChars(const S: string; const Chars: TSysCharSet): string;
{$IFDEF CLR}
var
  I: Integer;
  sb: StringBuilder;
begin
  sb := StringBuilder.Create(Length(S));
  for I := 0 to S.Length - 1 do
    if AnsiChar(S[I]) in Chars then
      sb.Append(S[I]);
  Result := sb.ToString();
end;
{$ELSE}
var
  Source, Dest: PChar;
  Len, Index: Integer;
begin
  Len := Length(S);
  SetLength(Result, Len);
  UniqueString(Result);
  Source := PChar(S);
  Dest := PChar(Result);
  for Index := 0 to Len-1 do
  begin
    if Source^ in Chars then
    begin
      Dest^ := Source^;
      Inc(Dest,SizeOf(Char));
    end;
    Inc(Source,SizeOf(Char));
  end;
  SetLength(Result, (Longint(Dest) - Longint(PChar(Result))) div SizeOf(Char));
end;

  b := StrStrKeepChars(a, ['0'..'9', '.', ',']);