Simulation of Home Automation Project using Arduino

1String voice;
2void setup() {
3Serial.begin(9600);
4pinMode(6, OUTPUT);
5pinMode(5,  OUTPUT);
6pinMode(4, OUTPUT);
7}
8
9void loop() {
10while(Serial.available()){
11  delay(3);
12  char c = Serial.read();
13  voice+=c;}
14
15if(voice.length()  >0){
16  Serial.println(voice);
17  if(voice == "light on")
18  {digitalWrite(6,  HIGH);}
19  else if(voice == "light off")
20  {digitalWrite(6, LOW);}
21  else  if(voice == "fan on")
22  {digitalWrite(5, HIGH);}
23  else if(voice == "fan  off")
24  {digitalWrite(5, LOW);}
25  else if(voice == "night lamp on")
26  {digitalWrite(4, HIGH);}
27  else if(voice == "night lamp off")
28  {digitalWrite(4,  LOW);}
29  else if(voice == "all on")
30  {digitalWrite(4, HIGH);
31    digitalWrite(5,  HIGH);
32  digitalWrite(6, HIGH);}
33  else if(voice == "all off")
34  {digitalWrite(4,  LOW);
35    digitalWrite(5, LOW);
36  digitalWrite(6, LOW);}
37  voice = "";}
38}
39