Install WiringPi on Rpi

wiringpi.com

RPi GPIO

$ gpio readall

BCM	wPi	Name	Mode	V	Physical	Physical	V	Mode	Name	wPi	BCM
		3.3v			1	2			5v
2	8	SDA.1	ALT0	1	3	4			5v
3	9	SCL.1	ALT0	1	5	6			0v
4	7	GPIO. 7	IN	1	7	8	1	ALT5	TxD	15	14
		0v			9	10	1	ALT5	RxD	16	15
17	0	GPIO. 0	IN	0	11	12	0	IN	GPIO. 1	1	18
27	2	GPIO. 2	IN	0	13	14			0v
22	3	GPIO. 3	IN	0	15	16	0	IN	GPIO. 4	4	23
		3.3v			17	18	0	IN	GPIO. 5	5	24
10	12	MOSI	ALT0	0	19	20			0v
9	13	MISO	ALT0	0	21	22	0	IN	GPIO. 6	6	25
11	14	SCLK	ALT0	0	23	24	1	OUT	CE0	10	8
		0v			25	26	1	OUT	CE1	11	7
0	30	SDA.0	IN	1	27	28	1	IN	SCL.0	31	1
5	21	GPIO.21	IN	1	29	30			0v
6	22	GPIO.22	IN	1	31	32	0	IN	GPIO.26	26	12
13	23	GPIO.23	IN	0	33	34			0v
19	24	GPIO.24	IN	0	35	36	0	IN	GPIO.27	27	16
26	25	GPIO.25	IN	0	37	38	0	IN	GPIO.28	28	20
		0v			39	40	0	IN	GPIO.29	29	21

Connect cables

DHT11	RPi GPIO
+	PIN1(3.3V)
DATA	PIN 7(GPIO7)
-	PIN 6(GND)

Compile on RPi

$ gcc dht11.c -l wiringPi -lm

$ ./a.out