const uint8_t digit[] = {
  //PGFEDCBA  Segments      7-segment map:
  0b00111111, // 0   "0"          AAA
  0b00000110, // 1   "1"         F   B
  0b01011011, // 2   "2"         F   B
  0b01001111, // 3   "3"          GGG
  0b01100110, // 4   "4"         E   C
  0b01101101, // 5   "5"         E   C
  0b01111101, // 6   "6"          DDD
  0b00000111, // 7   "7"
  0b01111111, // 8   "8"
  0b01101111  // 9   "9"
};
const uint8_t segmentPins[] = {7, 8, 2, 3, 4, 6, 5};// in simulator are resistors omitted
const uint8_t butPin = 12;
const uint8_t seg = 7;

void setup() {
  for (uint8_t i = 0; i < seg; i++) pinMode(segmentPins[i], OUTPUT);
  pinMode(butPin, INPUT_PULLUP);
  display(0);
}

void display(uint8_t num) {
  for (uint8_t i = 0; i < seg; i++)digitalWrite(segmentPins[i], digit[num] & (1 << i));
}

void loop() {
  static uint8_t var = 0;

  if (digitalRead(butPin) == LOW) {
    var++;
    if (var == 10)var = 0;
    display(var);
    delay(100);
    while (digitalRead(butPin) == LOW);
    delay(100);
  }

}