INTEGER CONSTANT

  An integer constant is a sequence of digits representing an integer
  value in the range -2147483648 to 2147483647. An integer constant
  must start with a digit from 0 to 9 or the negative sign (-) fol-
  lowed by a digit. The following are all valid integer constants:

       10
       -400067
       999

  An integer constant may also be entered in hexadecimal form (base
  16, where each digit may be from '0' to '9' or 'a' to 'f', to repre-
  sent 16 values). Hex values must be preceded by '0x' for the com-
  piler to interpret them as such, and case is not important. The fol-
  lowing are all valid integer constants enter in hexadecimal form:

       0xff00
       0Xa2
       0x7D
       0x1AbCdEf