Integer

An integer can be specified using one of three formats.

Decimal Integer Constants

A decimal integer constant is a stream of digits with non-leading zero, for example:

`123`	valid
`A123`	invalid (begins with non-digit)
`0123`	invalid (begins with zero but is a valid octal)

Octal Integer Constants

An octal integer constant is a stream of digits with a leading zero. The digits 8 and 9 have octal values 10 and 11 respectively. For example:

`0456`	valid (= 302 decimal)
`018`	valid (= 020 octal = 16 decimal)
`456`	invalid (but is a valid decimal)
`A456`	invalid (begins with non-digit)

Hexadecimal Integer Constants

An hexadecimal integer constant is a stream of hexadecimal digits starting with 0x (zero followed by the character x). Letters A to F have the hexadecimal values 10 to 15 respectively. Lowercase letters a to f are equivalent to their corresponding uppercase letters, for instance:

`0xAB`	valid (= 171 decimal)
`0x1f`	valid (= 31 decimal)
`AB`	invalid (begins with an alphabet letter)
`01f`	invalid (missing x)