A numeric value based on a radix of 16.

A hexadecimal value is an integer composed of only the following characters:

0 1 2 3 4 5 6 7 8 9

A B C D E F

a b c d e f

Note the use of the alphabetic characters to extend the decimal number digit set.

Hexadecimal values are always prefixed by a zero and X character.

The sequence carries over for the next increment when each column reaches the value F. Thus:

0x00 0x01 0x02 0x03 0x04 0x05 0x06 0x07

0x08 0x09 0x0A 0x0B 0x0C 0x0D 0x0E 0x0F

0x10 0x11 0x12 0x13 0x14 0x15 0x16 0x17

Hexadecimal values have a historical significance, having been used in the earliest computer systems. However, these days they are particularly useful since they map quite conveniently to the binary system. Each hexadecimal digit corresponds to four binary digits. Two hex digits map to a byte and four to a word. This is particularly useful and is evidenced by hexadecimal values being used to generate Unicode escape sequences.

There are several hexadecimal values that are useful. These are summarized in the following table:

 Value Description 0x0 All bits clear 0x20 The single bit to toggle between upper and lower case letters 0x7F A seven bit character mask 0x8000 The sign bit of a 16 bit integer value 0x80000000 The sign bit of a 32 bit integer value 0xDF A mask that excludes the upper/lower case bit 0xFF All bits set in a byte 0xFFFF All bits set in a 16 bit word 0xFFFFFFFF All bits set in a 32 bit word