PHP - Ds\Collection::isEmpty() Function

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The PHP Ds\Collection::isEmpty() function is used to determine whether the current collection is empty or not.

You can directly call this function on various collections such as a set, stack, vector, dequeue, etc. This function returns a boolean value 'true' if the current collection is empty and 'false' if it is not.

Syntax

Following is the syntax of the PHP Ds\Collection::isEmpty() function −

 abstract public bool Ds\Collection::isEmpty( void ) 

Parameters

This function does not accept any parameter.

Return value

This function returns 'true' if the current collection is empty, otherwise, it returns 'false'.

Example 1

If the current collection is empty, this function returns 'true'.

Following is a basic example of the PHP Ds\Collection::isEmpty() function −

 <?php $collection = new \Ds\Vector(); echo "Vector elements: \n"; print_r($collection); #using isEmpty() function $res = $collection->isEmpty(); print_r("Is this collection is empty? "); var_dump($res); ?> 

Output

The above program returns 'true' as shown in the output below −

 Vector elements: Ds\Vector Object ( ) Is this collection is empty? bool(true) 

Example 2

If the current collection is non-empty, this function returns 'false'.

Following is another example of the PHP Ds\Collection::isEmpty() function. We use this function to check whether this vector ([1, 2, 3, 4, 5]) (collection) is empty −

 <?php $collection = new \Ds\Vector([1, 2, 3, 4, 5]); echo "Vector elements: \n"; print_r($collection); #using isEmpty() function $res = $collection->isEmpty(); print_r("Is this collection is empty? "); var_dump($res); ?> 

Output

After executing the above program, it will return 'false' as shown in the below output −

 Vector elements: Ds\Vector Object ( [0] => 1 [1] => 2 [2] => 3 [3] => 4 [4] => 5 ) Is this collection is empty? bool(false) 

Example 3

In the example below of PHP Ds\Collection::isEmpty() function, we create a new empty vector (collection) and invoke the isEmpty() function on it before and after adding elements to see the results −

 <?php $vect = new \Ds\Vector(); echo "Before adding elements: \n"; $res = $vect->isEmpty(); echo "Is this collection is empty? "; var_dump($res); #adding elements $vect->push(121); $vect->push(272); $vect->push(31); $vect->push(26); $vect->push(99); $vect->push(81); echo "Vector elements are: \n"; print_r($vect); $res = $vect->isEmpty(); echo "After adding element to this collection: \n"; echo "Is this collection is empty? "; var_dump($res); ?> 

Output

Once the above program is executed, it will display the following output −

 Before adding elements: Is this collection is empty? bool(true) Vector elements are: Ds\Vector Object ( [0] => 121 [1] => 272 [2] => 31 [3] => 26 [4] => 99 [5] => 81 ) After adding element to this collection: Is this collection is empty? bool(false) 

Example 4

Let's use the isEmpty() function result in the conditional statement to check whether the current collection is empty or non-empty −

 <?php $seq = new \Ds\Vector(["test_string", 1525, false]); echo "Vector elements are: \n"; var_dump($seq); $res = $seq->isEmpty(); if($res){ print("Collection is empty"); }else{ print("Collection is not empty"); } ?> 

Output

On executing the above program, it will generate the following output −

 Vector elements are: object(Ds\Vector)#1 (3) { [0]=> string(11) "test_string" [1]=> int(1525) [2]=> bool(false) } Collection is not empty