Integer Constants
[Constants]
Description
Integer constants are numbers that are used directly in a sketch, like 123. By default, these numbers are treated as intbut you can change this with the U and L modifiers (see below).
Normally, integer constants are treated as base 10 (decimal) integers, but special notation (formatters) may be used to enter numbers in other bases.
| BASE | EXAMPLE | FORMATTER | COMMENT |
|---|---|---|---|
|
10 (decimal) |
123 |
none |
|
|
2 (binary) |
0b1111011 |
leading "0b" |
characters 0&1 valid |
|
8 (octal) |
0173 |
leading "0" |
characters 0-7 valid |
|
16 (hexadecimal) |
0x7B |
leading "0x" |
characters 0-9, A-F, a-f valid |
Decimal (base 10)
This is the common-sense math with which you are acquainted. Constants without other prefixes are assumed to be in decimal format.
Example Code:
n = 101; // same as 101 decimal ((1 * 10^2) + (0 * 10^1) + 1)Binary (base 2)
Only the characters 0 and 1 are valid.
Example Code:
n = 0b101; // same as 5 decimal ((1 * 2^2) + (0 * 2^1) + 1)Octal (base 8)
Only the characters 0 through 7 are valid. Octal values are indicated by the prefix "0" (zero).
Example Code:
n = 0101; // same as 65 decimal ((1 * 8^2) + (0 * 8^1) + 1)It is possible to generate a hard-to-find bug by (unintentionally) including a leading zero before a constant and having the compiler unintentionally interpret your constant as octal.
Hexadecimal (base 16)
Valid characters are 0 through 9 and letters A through F; A has the value 10, B is 11, up to F, which is 15. Hex values are indicated by the prefix "0x". Note that A-F may be upper (A-F) or lower case (a-f).
Example Code:
n = 0x101; // same as 257 decimal ((1 * 16^2) + (0 * 16^1) + 1)Notes and Warnings
U & L formatters:
By default, an integer constant is treated as an int with the attendant limitations in values. To specify an integer constant with another data type, follow it with:
-
a 'u' or 'U' to force the constant into an unsigned data format. Example: 33u
-
a 'l' or 'L' to force the constant into a long data format. Example: 100000L
-
a 'ul' or 'UL' to force the constant into an unsigned long constant. Example: 32767ul