ultrasonic sensor program

I wanted to make a suitable program for measuring distance using a Hc-sr04 (ultrasonic sensor) and Arduino Uno . The arduino board is showing a HIGH reading even when no LOAD is connected.Please also explain why cm and inch are return right after the variable long .

I used the following code:

int trigPin = 11;
int echoPin = 12;
long duration, cm, inches;

void setup() {
//Serial Port begin
Serial.begin (9600);
//Define inputs and outputs
pinMode(trigPin, OUTPUT);
pinMode(echoPin, INPUT);
}

void loop()
{

digitalWrite(trigPin, LOW);
delayMicroseconds(5);
digitalWrite(trigPin, HIGH);
delayMicroseconds(10);
digitalWrite(trigPin, LOW);

duration = pulseIn(echoPin, HIGH);

// convert the time into a distance
cm = (duration/2) / 29.1;

Serial.print(cm);
Serial.print("cm");

delay(250);
}

codeultrasonic.ino (947 Bytes)

Hi,
Try the software HERE HERE
I know it works...