int buttonPin = 4; // the number of the pushbutton pin
int ledPin = 8; // the number of the LED pin
// variables will change:
int buttonState = 0; // variable for reading the pushbutton status
void setup() {
 // initialize the LED pin as an output:
 pinMode(ledPin, OUTPUT);
 // initialize the pushbutton pin as an input:
 pinMode(buttonPin, INPUT);
}
void loop() {
 // read the state of the pushbutton value:
 buttonState = digitalRead(buttonPin);
 // check if the pushbutton is pressed. If it is, the buttonState is HIGH:
 if (buttonState == HIGH) {
 // turn LED on:
 digitalWrite(ledPin, HIGH);
 } else {
 // turn LED off:
 digitalWrite(ledPin, LOW);
 }
}