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How to use assertions with Arduino.
#include <assert.h>
// Pin 13 has an LED connected on most Arduino boards.
// give it a name:
int led = 13;
// the setup routine runs once when you press reset:
void setup() {
// initialize the digital pin as an output.
pinMode(led, OUTPUT);
// initialize serial communication at 9600 bits per second.
// the loop routine runs over and over again forever:
void loop() {
for (uint8_t i = 0; i < 3; i++) {
digitalWrite(led, HIGH); // turn the LED on (HIGH is the voltage level)
delay(1000); // wait for a second
digitalWrite(led, LOW); // turn the LED off by making the voltage LOW
delay(1000); // wait for a second
// make assertion failed.
// handle diagnostic informations given by assertion and abort program execution:
void __assert(const char *__func, const char *__file, int __lineno, const char *__sexp) {
// transmit diagnostic informations through serial link.
Serial.println(__lineno, DEC);
// abort program execution.

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@zacsketches zacsketches commented Mar 21, 2016

Thanks for documenting this. I was able to put it to use today.
Plus 1 star!


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@gundamlh gundamlh commented Sep 10, 2016

Many thanks for sharing! It works!


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@Pigeo Pigeo commented Jan 28, 2017

Unfortunately, it doesn't work on Arduino DUE :
__assert() function isn't called and I get the standard error message instead :

assertion "false" failed: file "/assert.ino", line 31, function: void loop()
Exiting with status 1.

Do you have any idea why it doesn't work on Arduino DUE ?
(However I successfully tested it on Arduino MEGA by the way)

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