7 segment

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

void setup() {
  pinMode(a, OUTPUT);
  pinMode(b, OUTPUT);
  pinMode(c, OUTPUT);
  pinMode(d, OUTPUT);
  pinMode(e, OUTPUT);
  pinMode(f, OUTPUT);
  pinMode(g, OUTPUT);
}
void displayDigit(int digit)
{
 if(digit!=1 && digit != 4)
 digitalWrite(a,HIGH);

 if(digit != 5 && digit != 6)
 digitalWrite(b,HIGH);

 if(digit !=2)
 digitalWrite(c,HIGH);

 if(digit != 1 && digit !=4 && digit !=7)
 digitalWrite(d,HIGH);

 if(digit == 2 || digit ==6 || digit == 8 || digit==0)
 digitalWrite(e,HIGH);

 if(digit != 1 && digit !=2 && digit!=3 && digit !=7)
 digitalWrite(f,HIGH);
 if (digit!=0 && digit!=1 && digit !=7)
 digitalWrite(g,HIGH);

}
void turnOff()
{
  digitalWrite(a,LOW);
  digitalWrite(b,LOW);
  digitalWrite(c,LOW);
  digitalWrite(d,LOW);
  digitalWrite(e,LOW);
  digitalWrite(f,LOW);
  digitalWrite(g,LOW);
}
void loop()
{
int i;
 for(i=0;i<10;i++)
 {
   displayDigit(i);
   delay(1000);
   turnOff();
 }
}