const — Maple v0.0.12 Documentation

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# `const`

The `const` keyword stands for “constant”. It is a variable qualifier that modifies the behavior of the variable, making a variable “read-only”. This means that the variable can be used just as any other variable of its type, but its value cannot be changed. You will get a compiler error if you try to assign a value to a `const` variable.

Constants defined with the `const` keyword obey the same rules of variable scoping that govern other variables. This, and the pitfalls of using #define, often makes using the `const` keyword a superior method for defining constants than `#define`.

## Example

>     // this defines a variable called "pi", which cannot be changed:
>     const float pi = 3.14;
>     float x;

>     // ....

>     x = pi * 2;    // it's fine to find the value of a const variable

>     pi = 7;        // illegal - you can't write to (modify) a constant

## #define or const

You can use either `const` or `#define` for creating numeric or string constants. For arrays, you will need to use `const`. In general, `const` is preferred over `#define` for defining constants.

## See Also

- #define
- volatile

License and Attribution

Portions of this page were adapted from the Arduino Reference Documentation, which is released under a Creative Commons Attribution-ShareAlike 3.0 License.

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