//int trig=8; int echo=7;
//#define trig 8 //here instead  of trig 8 will be replaced //but its not variables //just names 
// we can reduce the number of variable used
#define trig1 8
#define echo1 7
#define trig2 5
#define echo2 4

void setup() {
  // put your setup code here, to run once:
  pinMode(trig1, OUTPUT); pinMode(echo1, INPUT);
  pinMode(trig2, OUTPUT); //pwm pin not a problem
   pinMode(echo2, INPUT);
  Serial.begin(9600);

}

void loop() {
  // triggering
  //digitalWrite(trig, HIGH); delayMicroseconds(10); //we have set atleast 10 microseconds
  //digitalWrite(trig, LOW);

  //echo //the reflection of sound
  //unsigned long t = pulseIn(echo, HIGH); //duration in microseconds //long more size
  //select the best suitable data type
  //distance calculation
  //float d = 340 *(t/1000000.0)/2.0;
   //here 340 is speed of sound in air //1000000 is to convert to seconds 
  //2 is divided for that 2 distance(from start to reflecting point and back to start) 
  //Serial.println(d);
  //delay(100);

  Serial.print(getDistance(trig1, echo1));
  Serial.print(" ");
  Serial.println(getDistance(trig2, echo2));
  delay(100);


}
float getDistance(int trig , int echo)
{
  digitalWrite(trig, HIGH); delayMicroseconds(10); //we have set atleast 10 microseconds
  digitalWrite(trig, LOW);
  unsigned long t = pulseIn(echo, HIGH); //duration in microseconds //long more size
  float d = 340 *(t/1000000.0)/2.0;
  return d;
}