Converting between decimal, binary, and hexadecimal representation

USES
   StrUtils, SysUtils;

FUNCTION DecToBin(N: int64): STRING;
VAR
   i: integer;
   neg: boolean;
BEGIN
   IF N = 0 THEN BEGIN
      result := ’0’;
      exit
   END;
   SetLength(result, SizeOf(N) * 8);
   neg := N < 0;
   9
      N := Abs(N);
   i := 1;
   WHILE N <> 0 DO BEGIN
      IF N AND 1 = 1 THEN
         result[i] := ’1’
      ELSE
         result[i] := ’0’;
      N := N SHR 1;
      Inc(i);
   END;
   IF neg THEN BEGIN
      result[i] := ’’;
      Inc(i);
   END;
   Delete(result, i, length(result));
   result := ReverseString(result);
END;

FUNCTION DecToHex(N: int64): STRING;
BEGIN
   IF N < 0 THEN
      result := ’’
         + Format(’%0x’, [Abs(N)])
   ELSE
      result := Format(’%0x’, [N]);
END;