Convert a floating point into a character string (dtostrf)

Generally, sprintf is used to convert numbers such as floating points (float, double) to strings. However, as printf functions are large in scale, it is often unsuitable for microcontrollers such as Arduino. In fact, using sprintf on Arduino, %f will return ?.

char str[10];
sprintf(str, "%f", 10.8f);
// str == "?"

Instead, dtostrf provides an avr-libcfunction.

char str[10];
sprintf(10.8f, -1, 2, str);
// str == "10.80"

The parameters are, dtostrf(<number>, <right align>, <number of decimal places>, <string name>). Character string that are set to right align will be aligned to the right, and filled in with spaces to fulfill the total number of characters defined in the right align parameter. Numbers, periods and symbols all are counted as characters. number of decimal places is the number of digits to display after the decimal point. If right alignment is unnecessary, then set it as -1. This will make the string left aligned.