Seven Segment counter(0~15)

byte ccCode[16]={0x3F,0x06,0x5B,0x4F,0x66,0x6D,0x7D,0x07,0x7F,0x6F,0x77,0x7C,0x39,0x5E,0x79,0x71};
byte counter=0;

void setup() 
{
  //setting direction of PORTB & partial PORTD registers
  DDRB=B00111111;
  DDRD=B11000001;
  pinMode(3,INPUT_PULLUP);
  digitalWrite(0,LOW);
}

void loop() 
{
  bool buttonReleased=false;
  if(!digitalRead(3))
  {
    while(!buttonReleased)
    {
      delay(10); //delay added to avoid switch bouncing problem
      if(digitalRead(3)) buttonReleased = true;
    }
  }
  if(buttonReleased && counter<16) counter++;
  else if(counter == 16) counter=0;

  byte y=ccCode[counter];
  PORTB=y;
  bitWrite(PORTD,6,bitRead(y,6));
  bitWrite(PORTD,7,bitRead(y,7));
}