Arduino: printf/fprintf prints question mark instead of float

Question

I have the following code for an Arduino sketch:

#include 

LiquidCrystal lcd(12, 11, 5, 4, 3, 2);
static FILE lcdout = {0} ;

static          


        

Answer 1

From avr-libc documentation:

If the full functionality including the floating point conversions is required, the following options should be used:

-Wl,-u,vfprintf -lprintf_flt -l

Note that if your MCU doesn't have any floating point support, you should try to avoid floating point operations completely. The floating point operations will be done in software which is very inefficient and needs a lot a flash memory.