char* dtostrf(double __val, signed char __width, unsigned char __prec, char
*__s)
The dtostrf() function converts the double value passed in
val into an ASCII representationthat will be stored
under s. The caller is responsible for providing
sufficient storage in s.
Conversion is done in the format "[-]d.ddd". The
minimum field width of the output string (including the possible
'.' and the possible sign for negative values) is
given in width, and
prec determines the number of digits after the
decimal sign. width is signed value, negative for left
adjustment.
The dtostrf() function returns the pointer to the converted string
s.