'dtostrf' was not declared in this scope

Troubleshooting
1

I am trying to converting float to string , the code works fine with standard Arduino IDE but throwing the error in Spark IDE , my code looks like this… I have include #include “spark_wiring_string.h” , still no luck…

float h = dht.getHumidity();
float t = dht.getTempCelcius();

char floatTempString[10];

dtostrf(t,2,2,floatTempString);

please help me…

2

It is not declared in the header, so compiler can’t find it.

Why don’t you just use sprintf(floatTempString, "%2.2f", t)? It would be the same.

3

Thank You, I fixed this in diff. route , thanks to Dave’s prev. post. ,

float f = 43.0;
String s = String(f);
and do String concatenation , it is working now…

4

So dtostrf() is defined as a helper function in spark_wiring_string.cpp, but since it is not declared in the .h file, you would need to extern it to gain access.

It does not seem to be doc’ed in Arduino land, so I think the Spark team would have followed the doc in this case.

5

Still doesn’t seem to work without some tricks on Photon.

issues-with-converting-float-to-string-with-sprintf

I’m not sure if it is part of Arduino, but is found here AVR libc

If anyone has any updates on this issue that’d be great.