Float to Sting help

[ChrisOdom]

I have switched from a Teensy2 to a Teensy3 and now much of my code won't work. I've worked around most of the issues (using "while(!Serial){}", for example, after baud rate is established) but I am stuck on converting floats to strings for simple string concatenation. I was using dtostrf, but this doesn't work on the 3.0. I see that some suggest using sprintf, but I've not been able to make that work.

I would appreciate seeing a *simple* FULL code example to take the number 12.345 and have the message "number = 12.345" appear on the serial monitor.

Any assistance would be greatly appreciated. Thanks in advance!

[ChrisOdom]

"Float to stRing" help, that is.

[el_supremo]

float a = 12.345;

void setup(void)
{
  delay(1000);
  Serial.begin(9600);
  while(!Serial);
  Serial.print("number = ");
  Serial.println(a,3);
  
  char s[20];
  sprintf(s,"number = %6.3f",a);
  Serial.println(s);
}

void loop(void)
{
}

Pete

[ChrisOdom]

el_supremo, your name says it all. Thanks for your help, Pete. I'm not sure what I was doing wrong....

[ChrisOdom]

So after a bit more experimentation, I find that sprintf works fine on my Teensy3, but not on my Teensy2 or on my Arduino Uno. Is this to be expected? I'm not sure I understand what's going on under the hood.

I need code that works with all these boards; am I relegated to working only with print and println functions then?

[el_supremo]

dtostrf worked for me on Teensy3

Pete

[PaulStoffregen]

A recent version added dtostrf (using sprintf). If that function is missing on Teensy3, please upgrade to Teensyduino 1.15.

[ChrisOdom]

Thanks Paul and Pete. dtostrf now works on the Teensy3. I wish sprintf worked on the Teensy2.

[PaulStoffregen]

I wish sprintf worked on the Teensy2.

Perhaps try adding this to hardware/teensy/boards.txt

teensy2.build.linkoption1=-Wl,-u,vfprintf
teensy2.build.linkoption2=-lprintf_flt