SHT 75 sensor

Other Hardware Sensors
1

Could some one explain me what is this:

extern "C" { // AVR LibC Includes
#include <stddef.h>
#include <stdint.h>
#include <math.h>
}
// Wiring Core Includes
#include "Sensirion.h"
#if defined(ARDUINO) && ARDUINO >= 100
#include "Arduino.h"
#else
#include "WProgram.h"
#endif

i think this is because some libraries like "Wconstans.h" are included in one "arduino.h"
Am I right ? how is it working?

2

The "WProgram.h" was an inheritance from the past. With version 1.00 the common Arduino include file is called "Arduino.h".

You don't have to include that in your sketch. A library might have to include it.

This is Arduino.h : https://github.com/arduino/Arduino/blob/master/hardware/arduino/avr/cores/arduino/Arduino.h