int a = 2;
int b = 3;
int c = 4;
int d = 5;
int e = 6;
int f = 7;
int g = 8;
int dp = 9;

void setup()
{
  pinMode(a, OUTPUT);
  pinMode(b, OUTPUT);
  pinMode(c, OUTPUT);
  pinMode(d, OUTPUT);
  pinMode(e, OUTPUT);
  pinMode(f, OUTPUT);
  pinMode(g, OUTPUT);
  pinMode(dp, OUTPUT);
}

void loop()
{
  clearDisplay();
  delay(1000);

  displayNumber(1);
  delay(1000);

  displayNumber(2);
  delay(1000);

  displayNumber(3);
  delay(1000);

  displayNumber(4);
  delay(1000);

  displayNumber(5);
  delay(1000);

  displayNumber(6);
  delay(1000);

  displayNumber(7);
  delay(1000);

  displayNumber(8);
  delay(1000);

  displayNumber(9);
  delay(1000);
}

void clearDisplay()
{
  digitalWrite(a, HIGH);
  digitalWrite(b, HIGH);
  digitalWrite(c, HIGH);
  digitalWrite(d, HIGH);
  digitalWrite(e, HIGH);
  digitalWrite(f, HIGH);
  digitalWrite(g, HIGH);
  digitalWrite(dp, HIGH);
}

void displayNumber(int number)
{
  switch (number)
  {
    case 0:
      digitalWrite(a, LOW);
      digitalWrite(b, LOW);
      digitalWrite(c, LOW);
      digitalWrite(d, LOW);
      digitalWrite(e, LOW);
      digitalWrite(f, LOW);
      digitalWrite(g, HIGH);
      digitalWrite(dp, HIGH);
      break;
    case 1:
      digitalWrite(a, HIGH);
      digitalWrite(b, LOW);
      digitalWrite(c, LOW);
      digitalWrite(d, HIGH);
      digitalWrite(e, HIGH);
      digitalWrite(f, HIGH);
      digitalWrite(g, HIGH);
      digitalWrite(dp, HIGH);
      break;
    case 2:
      digitalWrite(a, LOW);
      digitalWrite(b, LOW);
      digitalWrite(c, HIGH);
      digitalWrite(d, LOW);
      digitalWrite(e, LOW);
      digitalWrite(f, HIGH);
      digitalWrite(g, LOW);
      digitalWrite(dp, HIGH);
      break;
    case 3:
      digitalWrite(a, LOW);
      digitalWrite(b, LOW);
      digitalWrite(c, LOW);
      digitalWrite(d, LOW);
      digitalWrite(e, HIGH);
      digitalWrite(f, HIGH);
      digitalWrite(g, LOW);
      digitalWrite(dp, HIGH);
      break;
    case 4:
      digitalWrite(a, HIGH);
      digitalWrite(b, LOW);
      digitalWrite(c, LOW);
      digitalWrite(d, HIGH);
      digitalWrite(e, HIGH);
      digitalWrite(f, LOW);
      digitalWrite(g, LOW);
      digitalWrite(dp, HIGH);
      break;
    case 5:
      digitalWrite(a, LOW);
      digitalWrite(b, HIGH);
      digitalWrite(c, LOW);
      digitalWrite(d, LOW);
      digitalWrite(e, HIGH);
      digitalWrite(f, LOW);
      digitalWrite(g, LOW);
      digitalWrite(dp, HIGH);
      break;
    case 6:
      digitalWrite(a, LOW);
      digitalWrite(b, HIGH);
      digitalWrite(c, LOW);
      digitalWrite(d, LOW);
      digitalWrite(e, LOW);
      digitalWrite(f, LOW);
      digitalWrite(g, LOW);
      digitalWrite(dp, HIGH);
      break;
    case 7:
      digitalWrite(a, LOW);
      digitalWrite(b, LOW);
      digitalWrite(c, LOW);
      digitalWrite(d, HIGH);
      digitalWrite(e, HIGH);
      digitalWrite(f, HIGH);
      digitalWrite(g, HIGH);
      digitalWrite(dp, HIGH);
      break;
    case 8:
      digitalWrite(a, LOW);
      digitalWrite(b, LOW);
      digitalWrite(c, LOW);
      digitalWrite(d, LOW);
      digitalWrite(e, LOW);
      digitalWrite(f, LOW);
      digitalWrite(g, LOW);
      digitalWrite(dp, HIGH);
      break;
    case 9:
      digitalWrite(a, LOW);
      digitalWrite(b, LOW);
      digitalWrite(c, LOW);
      digitalWrite(d, LOW);
      digitalWrite(e, HIGH);
      digitalWrite(f, LOW);
      digitalWrite(g, LOW);
      digitalWrite(dp, HIGH);
      break;
    default:
      clearDisplay();
      break;
  }
}