Arguments

 

nptr

   A pointer to the character string to be converted to an unsigned
   long.
 

endptr

   The address of an object where the function can store a pointer
   to a pointer to the first unrecognized character encountered in
   the conversion process (that is, the character that follows the
   last character in the string being converted). If endptr is a
   NULL pointer, the address of the first unrecognized character is
   not retained.
 

base

   The value, 2 through 36, to use as the base for the conversion.
   Leading zeros after the optional sign are ignored, and 0x or 0X
   is ignored if the base is 16.

   If the base is 0, the sequence of characters is interpreted by
   the same rules used to interpret an integer constant: after
   the optional sign, a leading 0 indicates octal conversion, a
   leading 0x or 0X indicates hexadecimal conversion, and any other
   combination of leading characters indicates decimal conversion.