arduino:constants:integerconstants
Differences
This shows you the differences between two versions of the page.
|
arduino:constants:integerconstants [2013/02/15 20:45] |
arduino:constants:integerconstants [2024/02/16 01:04] (current) |
||
|---|---|---|---|
| Line 1: | Line 1: | ||
| + | ======Integer Constants ====== | ||
| + | |||
| + | Integer constants are numbers used directly in a sketch, like //123//. By default, these numbers are treated as [[arduino:data_types:int|int]]'s but 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. | ||
| + | |||
| + | |||
| + | <code arduino> | ||
| + | Base Example Formatter Comment | ||
| + | |||
| + | 10 (decimal) 123 none | ||
| + | |||
| + | 2 (binary) B1111011 leading 'B' only works with 8 bit values (0 to 255) | ||
| + | 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 | ||
| + | </code> | ||
| + | |||
| + | |||
| + | **Decimal** is 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 arduino> | ||
| + | 101 // same as 101 decimal ((1 * 10^2) + (0 * 10^1) + 1) | ||
| + | </code> | ||
| + | \\ | ||
| + | |||
| + | **Binary** is base two. Only characters 0 and 1 are valid. | ||
| + | |||
| + | Example:<code arduino> | ||
| + | B101 // same as 5 decimal ((1 * 2^2) + (0 * 2^1) + 1) | ||
| + | </code> | ||
| + | The binary formatter only works on bytes (8 bits) between 0 (B0) and 255 (B11111111). If it is convenient to input an int (16 bits) in binary form you can do it a two-step procedure such as: | ||
| + | |||
| + | <code arduino> | ||
| + | myInt = (B11001100 * 256) + B10101010; // B11001100 is the high byte | ||
| + | </code> | ||
| + | |||
| + | |||
| + | **Octal** is base eight. Only characters 0 through 7 are valid. Octal values are indicated by the prefix "0" | ||
| + | |||
| + | Example: | ||
| + | <code arduino> | ||
| + | 0101 // same as 65 decimal ((1 * 8^2) + (0 * 8^1) + 1) </code> | ||
| + | ->Warning | ||
| + | ->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 (or hex)** is base sixteen. 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 syted in upper or lower case (a-f). | ||
| + | |||
| + | Example: | ||
| + | <code arduino> | ||
| + | 0x101 // same as 257 decimal ((1 * 16^2) + (0 * 16^1) + 1) | ||
| + | </code> | ||
| + | |||
| + | |||
| + | |||
| + | ==== U & L formatters ==== | ||
| + | |||
| + | By default, an integer constant is treated as an [[arduino:data_types:int|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// | ||
| + | \\ | ||
| + | |||
| + | |||
| + | ====See also ==== | ||
| + | * [[arduino:constants:Constants]] | ||
| + | * [[arduino:further_syntax:define|#define]] | ||
| + | * [[arduino:data_types:byte|byte]] | ||
| + | * [[arduino:data_types:int|int]] | ||
| + | * [[arduino:data_types:unsignedint| unsigned int]] | ||
| + | * [[arduino:data_types:long|long]] | ||
| + | * [[UnsignedLong | unsigned long]] | ||
| + | |||
| + | |||
| + | Source: arduino.cc | ||
on the occasion of the current invasion of Russia in Ukraine
Page Tools
Except where otherwise noted, content on this wiki is licensed under the following license: CC Attribution-Share Alike 3.0 Unported
