DWORD __stdcall HexaToDecimal(const char* pszHexa)
{
  DWORD ret = 0, t = 0, n = 8, c;
  while(c = *pszHexa) {
    if((c >= '0') && (c <= '9')) t = (c - '0');
    else if((c >= 'A') && (c <= 'F')) t = (c - 'A' + 10);
    else if((c >= 'a') && (c <= 'f')) t = (c - 'a' + 10);
    else break;
    ret *= 16; ret += t;
    pszHexa++;
    if(--n == 0) break;
  }
  return ret;
}

PROCEDURE HexaToDec( ValHex )
 RENVOYER Val( NumeriqueVersChaine( ValHex, "8d" )
PROCEDURE DecToHexa ( ValNumerique )
 RENVOYER NumeriqueVersChaine( ValNumerique, "x" )

# Decimal à hexadecimal
dh = lambda d: '%X' % d
# Hexadecimal à Decimal
hd = lambda h: int(h,16)

let rec hex_of_int n=
    let x=n mod 16
    and r=n/16
    in let prec=(
       if r=0 then ""
       else hex_of_int (n/16))
    in prec^
    (match x with
           10 ->  "A"
          |11->  "B"
          |12->  "C"
          |13->  "D"
          |14->  "E"
          |15->  "F"
          |nb-> string_of_int nb)
;;
hex_of_int 15;;(* string : F *)
let rec int_of_hex h=
    let len=string_length h
    in if len > 0
    then
        let x=h.[0]
        and m=int_of_hex (sub_string h 1 (len-1))
        in (match x with
             `A` -> 10
             |`B`-> 11
             |`C`-> 12
             |`D`-> 13
             |`E`-> 14
             |`F`-> 15
             | c -> int_of_char c)
        + m*16
    else 0
;;
int_of_hex "FF";;(* int : 255 *)

hex("deadbeef") # donne 3735928559