Arduino Define Constant

Description define is a useful C component that allows the programmer to give a name to a constant value before the program is compiled. Defined constants in arduino don't take up any program memory space on the chip. The compiler will replace references to these constants with the defined value at compile time.

Arduino boards have microcontrollers with notoriously small amounts of RAM. The Uno only has 2,048 bytes of static RAM available for your program to store variables. So when you need to keep non-changing variables out of RAM which is best to use const or define? What is define

This article details the basic syntax for defining constants, including libraries, making comments, and using punctuation in your Arduino programs. Defining constants define The define syntax allows the programmer to give a name to a constant value before the program is compiled, allowing any references to the constant to be replaced with the defined value when the program is

Arduino is an odd hybrid, where some C functionality is used in the embedded worldtraditionally a C environment. Indeed, a lot of Arduino code is very C like though. C has traditionally used defines for constants. There are a number of reasons for this You can't set array sizes using const int.

define is a useful C component that allows the programmer to give a name to a constant value before the program is compiled. Defined constants in arduino don't take up any program memory space on the chip. The compiler will replace references to these constants with the defined value at compile time.

Difference Between define and const in Arduino define. define is a pre-processor directive in Arduino programming. It's used to define symbolic constants or macros which can be used throughout the code. The main characteristic of define is that it performs a text replacement before the program is compiled.

For trivial examples, pin numbers and whatever, the const is usually better. But define is better used for calculation, where it looks more like a function.. In those cases, it is usually better to use an actual function, maybe with the inline compiler hint to encourage it to make the program faster by making it bigger.. Like any good tool, it can be used for many purposes, including

const variable. Constants defined with the const keyword obey the rules of variable scoping that govern other variables. This, and the pitfalls of using define, makes the const keyword a superior method for defining constants and is preferred over using define. Example Code

quotconst int PIN 1quot creates a constant variable that the compiler won't let you change, which is stored in the Arduino's memoryl. quotdefine PIN 1quot causes the precompiler to replace every instance of PIN in your code with 1 before the compiler runs saving you the 2 bytes of Arduino memory.

Avoid using define a text-based symbol substitution until you understand the problems that can arise when using it. I use const int to define an integer variable that is not allowed to change. It can catch some types of programming errors or typos. The maximum positive value of an quotintquot depends on the compiler.