PHP - Ds\PriorityQueue::isEmpty() Function

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The PHP Ds\PriorityQueue::isEmpty() function is used to check whether the queue is empty or not. This function does not take any arguments. And it return true the queue is empty and false if the queue is not empty.

Syntax

Below is the syntax of the PHP Ds\PriorityQueue::isEmpty() function −

public bool Ds\PriorityQueue::isEmpty( void )

Parameters

This function doesn't have any parameters.

Return Value

The isEmpty() function can return true if the queue is empty, or FALSE on failure.

PHP Version

This function is available from version 1.0.0 of the Ds extension onwards.

Example 1

Here we will show you the basic example of the PHP Ds\PriorityQueue::isEmpty() function to check whether the queue is empty or not and print the message accordingly.

<?php
   // Create a new PriorityQueue
   $pqueue = new \Ds\PriorityQueue();

   // Check if the queue is empty
   echo $pqueue->isEmpty() ? 'The queue is empty' : 'The queue is not empty'; 
?> 

Output

Following is the output of the above code −

The queue is empty

Example 2

In the below PHP code we will try to use the isEmpty() function after inserting elements in the created queue and check whether the queue is empty and print the message.

<?php
   // Create a new PriorityQueue
   $pqueue = new \Ds\PriorityQueue();
   $pqueue->push('A', 1);
   $pqueue->push('B', 2);
   
   echo $pqueue->isEmpty() ? 'The queue is empty' : 'The queue is not empty'; 
?> 

Output

This will generate the below output −

The queue is not empty

Example 3

Now in the below code we will add new elements to the queue and pop every element and then use isEmpty() function to check the emptiness of the queue.

<?php
   // Create a new PriorityQueue
   $pqueue = new \Ds\PriorityQueue();
   $pqueue->push('A', 1);
   $pqueue->push('B', 2);
   
   $pqueue->pop();
   $pqueue->pop();
   
   echo $pqueue->isEmpty() ? 'The queue is empty' : 'The queue is not empty';
?> 

Output

This will create the below output −

The queue is empty

Example 4

In the following example, we use the isEmpty() function to check two queues, one is empty and the second one is not empty.

<?php
   // Create a new PriorityQueue   
   $pqueue = new \Ds\PriorityQueue();  
         
   var_dump($pqueue->isEmpty()); 
        
   $pqueue->push("Tutorials", 1); 
   $pqueue->push("Point", 2); 
   $pqueue->push("India", 3); 
        
   var_dump($pqueue->isEmpty()); 
?>

Output

The above code will result something like this −

bool(true)
bool(false)