int switchPin =4;
int ledPin = 7;
int ledState = LOW;
int switchState = LOW;

int reading;


void setup() {
  pinMode(switchPin, INPUT);
  pinMode(ledPin, OUTPUT);
}

void loop() {
  reading  = (digitalRead(switchPin));
  if(reading !=switchState)
  {
    delay(25);//debounce method one (software delay),WIHTOUT dealy swithc will bounce
    if(reading==HIGH && switchState == LOW) ledState = ~ledState;
    digitalWrite(ledPin, ledState);
    switchState = reading;
    }
    // delay(25);
  }