PHP 7 Data Structures and Algorithms

Implementing a queue using PHP array

We are now going to implement the queue data structure using a PHP array. We have already seen that we can use the array_push() function to add an element at the end of the array. In order to remove the first element of the array, we can use the array_shift() function of PHP, and for the peek function, we can use the current() function of PHP. Here is how the code will look, based on our discussion:

class AgentQueue implements Queue {    private $limit;     private $queue;     public function __construct(int $limit = 20) {       $this->limit = $limit;       $this->queue = [];     }     public function dequeue(): string {       if ($this->isEmpty()) {           throw new UnderflowException('Queue is empty');       } else {  return array_shift($this->queue); ...