Infrared Matrix Password Input System with Arduino

I would like to introduce the Infrared Matrix Password Input System with Arduino, for more details:http://www.instructables.com/id/Infrared-Matrix-Password-Input-System-with-Arduino/

the code for this system as following:

#include <LiquidCrystal.h> //LCD library header files
#include <IRremote.h>//Infrared library header files
#include <Password.h> //Matrix keyboard password library header files
#include <Keypad.h> //Matrix keyboard library header files
#define uchar unsigned char
#define uint unsigned int
LiquidCrystal lcd(12, 11, 5, 4, 3, 2);//Define the LCD1602 pin connection
Password password = Password( "1234" );//Set up the matrix keyboard password

int RECV_PIN = 7;//Infrared receiver tube feet
const byte ROWS = 4; // Four rows
const byte COLS = 4; //  columns
char keys[ROWS][COLS] =
{
  {'1','2','3','A'},
  {'4','5','6','B'},
  {'7','8','9','C'},
  {'*','0','#','D'}
};// Create the Keypad

byte rowPins[ROWS] = { 31,33,35,37};// Connect keypad ROW0, ROW1, ROW2 and ROW3 to these Arduino pins.
byte colPins[COLS] = { 39,41,43,45};// Connect keypad COL0, COL1 and COL2 to these Arduino pins.

Keypad keypad = Keypad( makeKeymap(keys), rowPins, colPins, ROWS, COLS );
//Initializes the internal keymap to be equal to userKeymap

IRrecv irrecv(RECV_PIN);//Define a receiver input pin

decode_results results;//Save the decoding of variables results

int i=0;
long code_1,code_2,code_3,code_4,code_5;


void setup()
{
  lcd.begin(16, 2);
  lcd.setCursor(4,0);
  lcd.print("welcome");
  lcd.setCursor(4,1);
  irrecv.enableIRIn(); // Start the receiver
  keypad.addEventListener(keypadEvent); //add an event listener for this keypad
}

void loop()
{
  keypad.getKey();
  infrared();
}

void infrared()//Infrared password input
{
  if (irrecv.decode(&results)) //Decoding is successful, the data in the results variables
      {
        if(results.value!=4294967295)//Whether the infrared remote control has been hold
        {
          if(i==0)
          {
            code_1=results.value;
            infrareddisplay(code_1);//LCD display the corresponding infrared buttons
            i=1;
           }
       else  if(i==1)
          {
            code_2=results.value;
            infrareddisplay(code_2);
            i=2;
           }
       else  if(i==2)
          {
            code_3=results.value;
            infrareddisplay(code_3);
            i=3;
           }
       else  if(i==3)
          {
            code_4=results.value;
            infrareddisplay(code_4);
            i=4;
           }
        else  if(i==4)
          {
            if(results.value==16748655)
             {
               infrared_password();
             }
            i=0;
            lcd.clear();
            lcd.setCursor(4,0);
            lcd.print("welcome");
            lcd.setCursor(4,1);
           }
        }
        irrecv.resume(); // Receive the next value
       }
}

void infrared_password()//Infrared password comparison
{
  if(code_1==16724175)//The first value is 1
  {
    if(code_2==16718055)//The second value of 2
    {
      if(code_3==16743045)//The third value is 3
      {
        if(code_4==16716015)//The fourth value is 4
        {
          lcd.clear();
          lcd.setCursor(4,0);
          lcd.print("Success!");
          delay(2000);
          lcd.clear();
          lcd.setCursor(4,0);
          lcd.print("welcome");
          lcd.setCursor(4,1);
        }
        else
          {
            lcd.clear();
            lcd.setCursor(4,0);
            lcd.print("Wrong");
            delay(2000);
            lcd.clear();
            lcd.setCursor(4,0);
            lcd.print("welcome");
            lcd.setCursor(4,1);
          }
      }
      else
          {
            lcd.clear();
            lcd.setCursor(4,0);
            lcd.print("Wrong");
            delay(2000);
            lcd.clear();
            lcd.setCursor(4,0);
            lcd.print("welcome");
            lcd.setCursor(4,1);
          }
    }
    else
      {
        lcd.clear();
        lcd.setCursor(4,0);
        lcd.print("Wrong");
        delay(2000);
        lcd.clear();
        lcd.setCursor(4,0);
        lcd.print("welcome");
        lcd.setCursor(4,1);
      }
    }
    else
      {
        lcd.clear();
        lcd.setCursor(4,0);
        lcd.print("Wrong");
        delay(2000);
        lcd.clear();
        lcd.setCursor(4,0);
        lcd.print("welcome");
        lcd.setCursor(4,1);
      }
}
void infrareddisplay(long x)//LCD display the corresponding infrared buttons
{
  if(x==16738455)
  {
    lcd.print('0');
  }
  if(x==16724175)
   {
     lcd.print('1');
   }
   if(x==16718055)
   {
     lcd.print('2');
   }
   if(x==16743045)
  {
    lcd.print('3');
  }
  if(x==16716015)
  {
    lcd.print('4');
  }
  if(x==16726215)
   {
     lcd.print('5');
  }
  if(x==16734885)
   {
     lcd.print('6');
  }
  if(x==16728765)
   {
     lcd.print('7');
  }
  if(x==16730805)
   {
     lcd.print('8');
   }
   if(x==16732845)
    {
    lcd.print('9');
  }
  if(x==16748655)
  {
    infrared_password();
  }
}

void keypadEvent(KeypadEvent eKey)//Matrix keyboard password
{
  switch (keypad.getState())
  {
    case PRESSED:
        lcd.print(eKey);
	switch (eKey)
      {
	  case '#': checkPassword(); break;
	  case '*': password.reset(); break;
	  default: password.append(eKey);
       }
  }
}

void checkPassword()//Matrix keyboard password display
{
  if (password.evaluate())
  {
    lcd.clear();
        lcd.setCursor(5,0);
        lcd.print("Success!");
        delay(2000);
        lcd.clear();
        lcd.setCursor(5,0);
        lcd.print("welcome");
        lcd.setCursor(5,1);
  }
  else
  {
          lcd.clear();
          lcd.setCursor(5,0);
          lcd.print("Wrong");
          delay(2000);
          lcd.clear();
          lcd.setCursor(5,0);
          lcd.print("welcome");
          lcd.setCursor(5,1);
  }
}