The printed form of an integer consists of a sequence of digits optionally preceded by a minus sign (`-'). These are normally interpreted as base 10 integers. It is also possible to enter integers in base 2 (binary), 8 (octal), and 16 (hexadecimal); this is done by preceding the digit string by the string `0b', `0o', or `0x' respectively. The characters A-F or a-f stand for digits greater than 9. For example, the following tokens all represent the integer fifteen:
15 0b1111 0o17 0xf
Note that
+525
is not a valid integer.
There is also a special notation for character constants. E.g.:
0'A 0'\x41\ 0'\101\
are all equivalent to 65 (the character code for `A').
`0'' followed by any character except `\' (backslash) is
thus read as an integer. If `0'' is followed by `\', the
`\' denotes the start of an escape sequence with special meaning
(see ref-syn-syn-esc).