constrain()

(Macro) Constrains a number to be within a range.

Syntax

constrain(x, a, b)

Parameters

x: the number to constrain

a: the lower end of the range

b: the upper end of the range

Returns

x: if x is between a and b

a: if x is less than a

b: if x is greater than b

Example

// limits range of sensor values to between 10 and 150:
sensVal = constrain(sensVal, 10, 150);

Warning

Because of the way constrain() is implemented, avoid using other functions or causing side effects inside the parentheses, as it may lead to incorrect results:

constrain(x,a++,b);   // avoid this - yields incorrect results

constrain(x,a,b);     // use this instead-
a++;                  // keep other math outside constrain()

Arduino Compatibility

Maple’s implementation of constrain() is compatible with Arduino.

See also

• min()
• max()

License and Attribution

This documentation page was adapted from the Arduino Reference Documentation, which is released under a Creative Commons Attribution-ShareAlike 3.0 License.