Printing a zero value uint64_t number fails.

[greiman]

Here is a test case:

void setup() {
  Serial.begin(9600);
  while (!Serial) {}
  uint64_t n = 123;
  uint64_t m = n;
  Serial.print("n - m = ");
  Serial.println(n - m);
  n++;
  Serial.print("n - m = ");
  Serial.println(n - m);
}
void loop() {}

The output is:

n - m =
n - m = 1

The problem is in printULLNumber here

I can see how zero fails but am not sure of the best fix.

Probably the while needs to be a do while loop.

[earlephilhower]

Can you give an MCVE? It works fine as far as I can tell:

void setup() {
}
uint64_t uz = 0;
void loop() {
    Serial.printf("%" PRIu64 "\n", uz);
    delay(500);
}

gives

0
0
0
...

[greiman]

Sorry, I accidentally hit comment too soon. see the above example.

[earlephilhower]

Ah, thanks. Arduino reinventing vfprintf and not actual printf which makes sense (the Serial.printf bit is handled by Newlib which I'm sure is good).

You might want to push this upstream to the main ArduinoCore-API repo since this is untouched Arduino.cc code.

[earlephilhower]

arduino/ArduinoCore-API#178

Already opened 9 months ago.