Unsigned long printed as long

[pinps]

Hi,
I am trying to print an unsigned long value ID on Arduin Uno, but it seems to print it as a long:
Code:
void setup() {
Serial.begin(9600);
StaticJsonBuffer<200> jsonBuffer;
JsonObject& root = jsonBuffer.createObject();
root["id"] = 2345678901;
root.printTo(Serial);
}
Output:
{"id":-1949288395}

Do I need to specify some how it is an unsigned or how to fix this behavior?

-Pinps

[bblanchon]

Hi,

Internally, every value of an integral type is casted to long.
Currently, there is no plan to add support for unsigned long, because it'd increase the size of the code significantly.

Here are two workarounds:

root["id"] = double_with_n_digits(2345678901, 0);
root["id"] = ArduinoJson::Internals::Unparsed("2345678901");

Sorry about that.

[bblanchon]

After thinking about it, I think I can change the internal storage to be unsigned long and add a variant type for negative value.
That way the impact on code size would be reasonable.

Anyway, I'm adding support for long long right now, I'll see how I can add this feature whe it's done.

[pinps]

Thanks for workaround. The double_with_n_digits truncated last bits but unparsed worked great:

unsigned long id = 2345678901;
char buf[11];
sprintf(buf,"%lu",id);
root["id"] = ArduinoJson::Internals::Unparsed(buf);

Output now: {"id":2345678901}

[bblanchon]

You may have to write:

root["id"] = ArduinoJson::Internals::Unparsed(jsonBuffer.strdup(buf));

if buf goes out of scope.

[bblanchon]

I fixed the issue one month ago, but I was waiting for this pull request to be merged.
Without this fix in the Arduino core, this feature will increase the size of the code.