const byte a = 6, b = 5, c = 4, d = 3, e = 2, f = 1, g = 0;
void setup() {
for (byte i = 0; i <= 6; i++)
{
 pinMode(i, OUTPUT); // 0 - 6 pinleri çıkış yap.
}
}
void loop() {
for (byte rakam = 0; rakam <= 9; rakam++) { // Rakamları yukarı say.
 switch (rakam) { // Rakam değişkenini seçeneklerden bul.
 case 0 :
 digitalWrite(a, HIGH);
 digitalWrite(b, HIGH);
 digitalWrite(c, HIGH);
 digitalWrite(d, HIGH);
 digitalWrite(e, HIGH);
 digitalWrite(f, HIGH);
 digitalWrite(g, LOW);
 break;
 case 1:
 digitalWrite(a, LOW);
 digitalWrite(b, HIGH);
 digitalWrite(c, HIGH);
 digitalWrite(d, LOW);
 digitalWrite(e, LOW);
 digitalWrite(f, LOW);
 digitalWrite(g, LOW);
 break;
case 2:
 digitalWrite(a, HIGH);
 digitalWrite(b, HIGH);
 digitalWrite(c, LOW);
 digitalWrite(d, HIGH);
 digitalWrite(e, HIGH);
 digitalWrite(f, LOW);
 digitalWrite(g, HIGH);
 break;
 case 3:
 digitalWrite(a, HIGH);
 digitalWrite(b, HIGH);
 digitalWrite(c, HIGH);
 digitalWrite(d, HIGH);
 digitalWrite(e, LOW);
 digitalWrite(f, LOW);
 digitalWrite(g, HIGH);
 break;
 case 4:
 digitalWrite(a, LOW);
 digitalWrite(b, HIGH);
 digitalWrite(c, HIGH);
 digitalWrite(d, LOW);
 digitalWrite(e, LOW);
 digitalWrite(f, HIGH);
 digitalWrite(g, HIGH);
 break;
 case 5:
 digitalWrite(a, HIGH);
 digitalWrite(b, LOW);
 digitalWrite(c, HIGH);
 digitalWrite(d, HIGH);
 digitalWrite(e, LOW);
 digitalWrite(f, HIGH);
 digitalWrite(g, HIGH);
 break;
 case 6:
 digitalWrite(a, HIGH);
 digitalWrite(b, LOW);
 digitalWrite(c, HIGH);
 digitalWrite(d, HIGH);
 digitalWrite(e, HIGH);
 digitalWrite(f, HIGH);
 digitalWrite(g, HIGH);
 break;
case 7:
 digitalWrite(a, HIGH);
 digitalWrite(b, HIGH);
 digitalWrite(c, HIGH);
 digitalWrite(d, LOW);
 digitalWrite(e, LOW);
 digitalWrite(f, LOW);
 digitalWrite(g, LOW);
 break;
 case 8:
 digitalWrite(a, HIGH);
 digitalWrite(b, HIGH);
 digitalWrite(c, HIGH);
 digitalWrite(d, HIGH);
 digitalWrite(e, HIGH);
 digitalWrite(f, HIGH);
 digitalWrite(g, HIGH);
 break;
 case 9:
 digitalWrite(a, HIGH);
 digitalWrite(b, HIGH);
 digitalWrite(c, HIGH);
 digitalWrite(d, HIGH);
 digitalWrite(e, LOW);
 digitalWrite(f, HIGH);
 digitalWrite(g, HIGH);
 break;
 } // switch case bitti.
} // for döngüsü bitti.
}