Using Rotary Encoders with Arduino interrupts

int counter=5;
String dir="";
unsigned long last_run=0;


void setup() {
  Serial.begin(9600);
  attachInterrupt(digitalPinToInterrupt(3), shaft_moved, FALLING);
  pinMode(4,INPUT);
}

void shaft_moved(){
  if (millis()-last_run>5){
    if (digitalRead(4)==1){
      if(counter<10) counter++;
      dir="CW";
      }
    if (digitalRead(4)==0){
      if (counter>5) counter--; 
      dir="CCW";}
    last_run=millis();
  }
}

void loop() {
  Serial.print("counter : ");
  Serial.print(counter);
  Serial.print(" direction : ");
  Serial.println(dir);  
}

int DS1_pin = 6;
int STCP1_pin =9;
int SHCP1_pin = 8 ;
int DT_pin = 5;

int counter=0;
unsigned long last_run=0;

int digits [10][8]{
  {0,1,1,1,1,1,1,0}, // digit 0
  {0,0,1,1,0,0,0,0}, // digit 1
  {0,1,1,0,1,1,0,1}, // digit 2
  {0,1,1,1,1,0,0,1}, // digit 3
  {0,0,1,1,0,0,1,1}, // digit 4
  {0,1,0,1,1,0,1,1}, // digit 5
  {0,1,0,1,1,1,1,1}, // digit 6
  {0,1,1,1,0,0,0,0}, // digit 7
  {0,1,1,1,1,1,1,1}, // digit 8
  {0,1,1,1,1,0,1,1}  // digit 9
};


void DisplayDigit(int Digit)
{
    digitalWrite(STCP1_pin,LOW);
    for (int i = 7; i>=0; i--)
   {
    digitalWrite(SHCP1_pin,LOW);
    if (digits[Digit][i]==1) digitalWrite(DS1_pin, LOW); 
    if (digits[Digit][i]==0) digitalWrite(DS1_pin, HIGH);
    digitalWrite(SHCP1_pin,HIGH);
   }
   digitalWrite(STCP1_pin, HIGH); 
}

void shaft_moved(){
  if (millis()-last_run>5){
    if (digitalRead(4)==1){
      if (counter<9) counter++; 
    }
    if (digitalRead(4)==0){
      if(counter>0) counter--; 
    }
  last_run=millis();
  }
}

void reset_to_0(){
  counter=0;
}

void setup() {  
  pinMode(DS1_pin, OUTPUT);
  pinMode(STCP1_pin, OUTPUT);
  pinMode(SHCP1_pin, OUTPUT);
  attachInterrupt(digitalPinToInterrupt(3), shaft_moved, LOW);
  attachInterrupt(digitalPinToInterrupt(2), reset_to_0, FALLING);
  pinMode(2,INPUT_PULLUP);
  pinMode(DT_pin,INPUT);
}

void loop() {  
  DisplayDigit(counter);  
}