ltoa != itoa

[mongozmaki]

Hi,
I discovered, that the non-ISO ltoa function is not equal to itoa for the maximal negative value case (-2147483648 or LONG_MIN).

I'm not sure if this is a bug or this behaviour is ok.

The reason is the implementation (usage of the abs function) of ltoa which cannot convert the maximal negative value to a positive integer (--2147483648 not representable).

Test code:

    Serial.print("INT_MIN String: ");
    Serial.println(String(std::numeric_limits<int>::min())); //-2147483648

    Serial.print("LONG_MIN String: ");
    Serial.println(String(std::numeric_limits<long>::min())); //Weird String

    Serial.print("size long: ");
    Serial.println(sizeof(long));

    Serial.print("size int: ");
    Serial.println(sizeof(int));

One workaround would be to add a switch in core_esp8266_noniso.c::ltoa:

if (sizeof(long) == sizeof(int) {
  return itoa(...);
}
else {
  //Current code ...
}

or to handle this border-case separately.

[devyte]

@igrr do you have any comments on the proposed fix?

[earlephilhower]

@mongozmaki There's a very recent commit fixing this in String. Should be clean, now.

[mongozmaki]

I saw it, Thanks a lot!

[earlephilhower]

I'll close this, then. Thx