constrain

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Description

Clips a number to a specified value range.

Notes:

• Because of the way the constrain() function is implemented, using other functions inside the brackets may lead to incorrect results. For example, avoid constrain(x++,a,b).

Inclusion

• defined in misc.h
• auto-loaded in main_general.h
• no #define required

Syntax

y = constrain(x, a, b)

Parameters

• input:

  • x: the number to constrain
  • a: lower range limit
  • b: upper range limit

• output:

  • none

Returns

• x: if x is between a and b
• a: if x is less than a
• b: if x is greater than b

Example Code

The below code prints the values from -10..10, clipped to [-5;5].

#include "main_general.h"
#include "uart1.h"
#include "putchar.h"
    
void setup()
{
  int i;

  // init UART1 to 115.2kBaud, 8N1, full duplex
  UART1_begin(115200);

  // use UART1 for printf() output
  putcharAttach(UART1_write);

  // allow terminal to launch
  sw_delay(1000);

  // print values
  for (i=-10; i<=10; i++)
    printf("%d  %d\n", i, constrain(i,-5,5));

}

void loop()
{
  // dummy
}

Relevant Tutorial

• tbd

See also

• inRange()
• map()
• scale()