const int led = 22;
const int button = 15;
boolean onoff = LOW;

void setup() {
  pinMode (led,OUTPUT);
  pinMode (button,INPUT_PULLUP);
}

void loop() {
  if (digitalRead (button)==LOW){
    delay(50);
    if (digitalRead (button)==LOW){
      onoff =!onoff;
      digitalWrite(led,!digitalRead(led));
    }
    while (digitalRead (button)==LOW);
  }
}