pushbutton arduino with led code example

Example: arduino rgb led with pushbutton

#define button 11
#define redLED 8
#define greenLED 9
#define blueLED 10
int state = 0;
int old = 0;
int buttonPoll = 0;

void setup() {
 pinMode(button,INPUT);
 //RGB LED set as output
 pinMode(redLED,OUTPUT);
 pinMode(greenLED,OUTPUT);
 pinMode(blueLED,OUTPUT);

 digitalWrite(redLED,LOW);
 digitalWrite(greenLED,LOW);
 digitalWrite(blueLED,LOW);
}

void loop() {
 buttonPoll = digitalRead(button);
 if(buttonPoll == 1) {
 delay(50);
 buttonPoll = digitalRead(button);
 if(buttonPoll == 0) {
 state = old + 1;
 }
 }
 else {
 delay(100);
}

switch (state) {
 case 1: //Red color
 digitalWrite(redLED,HIGH);
 digitalWrite(greenLED,LOW);
 digitalWrite(blueLED,LOW);
 old = state;
 break;
 case 2: //Green color
 digitalWrite(redLED,LOW);
 digitalWrite(greenLED,HIGH);
 digitalWrite(blueLED,LOW);
 old = state;
 break;
 case 3: //Blue color
 digitalWrite(redLED,LOW);
 digitalWrite(greenLED,LOW);
 digitalWrite(blueLED,HIGH);
 old = state; 
 break;
 case 4: //Purple color
 digitalWrite(redLED,HIGH);
 digitalWrite(greenLED,LOW);
 digitalWrite(blueLED,HIGH);
 old = state; 
 break;
 case 5: //White color
 digitalWrite(redLED,HIGH);
 digitalWrite(greenLED,HIGH);
 digitalWrite(blueLED,HIGH);
 old = state; 
 break;
 default:
 digitalWrite(redLED,LOW);
 digitalWrite(greenLED,LOW);
 digitalWrite(blueLED,LOW);
 old = 0;
 break;
 }
}