title: dynamic array declaration in arduino
body: <p>I am trying to make a code that unlocks a door when a correct passcode is given. But, while doing that, I came across a problem. I had to store the passcode entered in a dynamic array. I know that there is a package for making a dynamic array But I don't know the code for making the dynamic array. I am posting the code I have done till now that is, only starting up the keypad.</p>
  <pre><code>#include &lt;Keypad.h&gt;
  const byte ROWS = 4;
  const byte COLS = 4;
  char keys[ROWS][COLS] = {
  {'1','2','3','A'},
  {'4','5','6','B'},
  {'7','8','9','C'},
  {'*','0','#','D'}
  };
  
  byte rowPins[ROWS] = { 8, 7, 6, 9 };
  byte colPins[COLS] = { 5, 4, 3, 2 };
  Keypad keypad = Keypad( makeKeymap(keys), rowPins, colPins, ROWS, COLS );
  
  void setup() {
  
    // put your setup code here, to run once:
    Serial.begin(9600);
  
  }
  
  void loop() {
  
    // put your main code here, to run repeatedly:
  
  }
  </code></pre>