const int relayPin = 2; //the base of the transistor attach to
int comdata = 0;

void setup()
{
  pinMode(relayPin, OUTPUT);  //initialize the LED as output
  Serial.begin(9600);  // start serial port at 9600 bps:
  while (! Serial);
  Serial.println("Please input your command to control this Lamp:");  //print message on serial monitor
}
void loop()
{
 //read string from serial monitor
  if(Serial.available())    // check if data has been sent from the computer
  {  comdata= Serial.read();
       if(comdata == 49)
    {
      digitalWrite(relayPin, HIGH);//turn the lamp on
      Serial.println("light is on");
    }
    else if(comdata == 48)
    {
      digitalWrite(relayPin, LOW);//turn the lamp off
      Serial.println("light is off");
    } 
  }
}