byte digits[] = {0x7e, 0x30, 0x6d, 0x79, 0x33, 0x5b, 0x5f, 0x70, 0x7f, 0x7b};
byte cathodePins[] = {0x70, 0xb0, 0xd0, 0xe0};

int dataPin = 2;
int clockPin = 3;
int latchPin = 4;

void setup() {
  // put your setup code here, to run once:
  pinMode(dataPin, OUTPUT);
  pinMode(clockPin, OUTPUT);
  pinMode(latchPin, OUTPUT);

}

void loop() {
   for(int i = 0; i < 100; i++){
      printDigits(i);

      delay(100);
   }
}
void printDigits(int num){
   
    if(num >= 0 || num <=99){
        
         digitalWrite(latchPin, LOW);
         shiftOut(dataPin, clockPin, MSBFIRST, digits[num % 10]);
         shiftOut(dataPin, clockPin, MSBFIRST, cathodePins[0]);
         digitalWrite(latchPin, HIGH);
         delay(33);
    
        if(num > 9 ){
        
           digitalWrite(latchPin, LOW);
           shiftOut(dataPin, clockPin, MSBFIRST, digits[(num/10) % 10]);
           shiftOut(dataPin, clockPin, MSBFIRST, cathodePins[1]);
           digitalWrite(latchPin, HIGH);
           delay(33);
           if(num > 99){
             
              digitalWrite(latchPin, LOW);
              shiftOut(dataPin, clockPin, MSBFIRST, digits[(num/100) % 10]);
              shiftOut(dataPin, clockPin, MSBFIRST, cathodePins[2]);
              delay(33);

           }
        }
    }
}
/*void printDigits(int num){

       digitalWrite(latchPin, LOW);
       shiftOut(dataPin, clockPin, MSBFIRST, digits[num % 10]);
       shiftOut(dataPin, clockPin, MSBFIRST, cathodePins[0]);
       digitalWrite(latchPin, HIGH);
       delay(33);
       digitalWrite(latchPin, LOW);
       shiftOut(dataPin, clockPin, MSBFIRST, digits[(num/10) % 10]);
       shiftOut(dataPin, clockPin, MSBFIRST, cathodePins[1]);
       digitalWrite(latchPin, HIGH);
       delay(33);
       digitalWrite(latchPin, LOW);
       shiftOut(dataPin, clockPin, MSBFIRST, digits[(num/100) % 10]);
       shiftOut(dataPin, clockPin, MSBFIRST, cathodePins[2]);
       digitalWrite(latchPin, HIGH);
       delay(33);
       digitalWrite(latchPin, LOW);
       shiftOut(dataPin, clockPin, MSBFIRST, digits[(num/1000) % 10]);
       shiftOut(dataPin, clockPin, MSBFIRST, cathodePins[3]);
       digitalWrite(latchPin, HIGH);
       delay(33);
  }*/