Power +Ve (3.3VDC to 5.5VDC Max wrt. GND)
Serial Data Output
Power Ground or Power –Ve
go for this sensor as the other variant DHT-22 costs rs 500 and this one costs rs 200. it has a lesser resolution compared to the DHT-22.one difficulty while trying to interface the sensor was figuring out the corresponding pins. there are 3 pins as seen from the pic but it is unclear which pin is which. Also if u try to search on the net different results gave different pin configurations. if you look closely you will find an S on the signal pin side and a - on the ground pin side. the Vcc pin is unmarked. thats how i figured the pin connections.
Also the sensor has an internal pulldown resistor included to the chip. So no need of adding extra resistor.