5. switch case

// C++ code
//
int i=0;
const int ledM=11;
const int ledK=12;
const int ledH=10;
const int pbKanan=6;
const int pbKiri=5;
int hasilpbKanan;
int hasilpbKiri;

void setup()
{
  Serial.begin(9600);
  pinMode(ledM,OUTPUT);
  pinMode(ledK,OUTPUT);
  pinMode(ledH,OUTPUT);
  pinMode(pbKanan,INPUT);
  pinMode(pbKiri,INPUT);
}

void loop()
{
  hasilpbKiri=digitalRead(pbKiri);
  if(hasilpbKiri==1){
    i++;
    delay(300);
  } 
  hasilpbKanan=digitalRead(pbKanan);
  if(hasilpbKanan==1){
    i--;
    delay(300);
  } 
  switch(i){
    case 1:
    	digitalWrite(ledM, HIGH);
    	digitalWrite(ledH, LOW);
    	digitalWrite(ledK, LOW);
    	break;
    case 2:
    	digitalWrite(ledK, HIGH);
    	digitalWrite(ledM, LOW);
    	digitalWrite(ledH, LOW);
    	break;
    case 3:
    	digitalWrite(ledH, HIGH);
    	digitalWrite(ledM, LOW);
    	digitalWrite(ledK, LOW);
    	break;
    default:
    	digitalWrite(ledM, LOW);	// jawaban dari PR nih
    	digitalWrite(ledK, LOW);
    	digitalWrite(ledH, LOW);
    	if(i>=4){					// improvisasi biar ngga bablas
      		i=4;
    	} 
    	if(i<=0){
      		i=0;
    	} 
    	break;
  } 
  Serial.println(i);
}

Source : Youtube Life Tech