#include <LiquidCrystal.h>
#include <Keypad.h>
#define pass_len 7

LiquidCrystal lcd(22, 21, 20, 19, 18, 17);
char Data[pass_len]; 
char Master[pass_len] = "BCD246"; 
byte data_count = 0, master_count = 0;
bool pass_true;
char cus_key;

const uint8_t row = 4;
const uint8_t col = 4;

char keys[row][col] = {
  {'1','2','3','A'},
  {'4','5','6','B'},
  {'7','8','9','C'},
  {'*','0','#','D'}
};

uint8_t rowPins[row] = {9, 8, 7, 6}; 
uint8_t colPins[col] = {5, 4, 3, 2};

Keypad keypad = Keypad(makeKeymap(keys), rowPins, colPins, row, col);

void setup() {
}

void loop() {
  lcd.setCursor(0,0);
  lcd.print("Input Password:");
  cus_key = keypad.getKey();

  if (cus_key) // makes sure a key is actually pressed, equal to (customKey != NO_KEY)
  {
    Data[data_count] = cus_key; // store char into data array
    lcd.setCursor(data_count,1); // move cursor to show each new char
    lcd.print(Data[data_count]); // print char at said cursor
    data_count++; // increment data array by 1 to store new char, also keep track of the number of chars entered
  }

  if(data_count == pass_len-1) // if the array index is equal to the number of expected chars, compare data to master
  {
    lcd.clear();
    lcd.setCursor(0,0);
    lcd.print("Pwd ");

    if(!strcmp(Data, Master)) // equal to (strcmp(Data, Master) == 0)
      lcd.print("Accepted");
    else
      lcd.print("Denied");

    delay(1000);// added 1 second delay to make sure the password is completely shown on screen before it gets cleared.   
    lcd.clear();
    clearData();
  }
}

void clearData()
{
  while(data_count !=0)
  {   // This can be used for any array size, 
    Data[data_count--] = 0; //clear array for new data
  }
  return;
}