LED blinking as much as button counter

Using Arduino Programming Questions
#1

Please explain me how this code works…

const int switchPin=2;
const int ledPin=13;
int state=0;
int lastState=0;
int count=0;
unsigned long a=0; 
const long b=1000; 

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

void loop() {
  state=digitalRead(switchPin);
  if(state!=lastState){
    if(state==HIGH){
      count++;
      a=millis();     
    }
    lastState=state;
  }
  if(a+b<millis()){
    switch(count){
      case 1:
      digitalWrite(ledPin, HIGH);
      delay(200);
      digitalWrite(ledPin, LOW);
      delay(200);
      break;
      case 2:
      for(int i=0;i<2;i++){
        digitalWrite(ledPin, HIGH);
        delay(200);
        digitalWrite(ledPin, LOW);
        delay(200);
      }
      break;
      case 3:
      for(int i=0;i<3;i++){
        digitalWrite(ledPin, HIGH);
        delay(200);
        digitalWrite(ledPin, LOW);
        delay(200);
      }
      break;
      case 4:
      for(int i=0;i<4;i++){
        digitalWrite(ledPin, HIGH);
        delay(200);
        digitalWrite(ledPin, LOW);
        delay(200);
      }
      break;
      case 5:
      for(int i=0;i<5;i++){
        digitalWrite(ledPin, HIGH);
        delay(200);
        digitalWrite(ledPin, LOW);
        delay(200);
      }
    }
    count=0;
  }
  delay(20);
}

Thanks

#2

That question is too broad.

Where did you get the sketch?

What part of the sketch are you not understanding?

What is not working for you?

#3

#4

The code sets ledPin HIGH and then later LOW and then does it again. That's why the LED is blinking.

Steve

#5