this is the code i an using
void loop() {
unsigned long t;
unsigned long t2;
unsigned long pulse_width;
float cm;
float inches;
// Hold the trigger pin high for at least 10 us
digitalWrite(TRIG_PIN, HIGH);
delayMicroseconds(10);
digitalWrite(TRIG_PIN, LOW);
// Wait for pulse on echo pin
while ( digitalRead(ECHO_PIN) == 0 );
// Measure how long the echo pin was held high (pulse width)
t = micros();
while ( digitalRead(ECHO_PIN) == 1);
//t22 = micros();
t2 = micros();
pulse_width = t2 – t;// this line is giving stray in program error
// i do not know why?
//
cm = pulse_width / 58.0;
inches = pulse_width / 148.0;