PHP - Ds\Collection::clear() Function

ThePHP Ds\Collection::clear()function removes all values from a collection. You can directly invoke this functionon the created collection object to make this collection empty, and later on, you can check using the count() or isEmpty() function whether it is empty.

Syntax

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

abstract public void Ds\Collection::clear( void )

Parameters

This function does not accept any parameter.

Return value

This function doesn't return any values, instead makes the collection empty.

Example 1

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

<?php 
   $collection = new \Ds\Vector(["Mango", "Apple", "Banana", "Orange"]);
   echo "Vector elements are: \n";
   var_dump($collection);
   #using clear() function
   $collection->clear();
   echo "Vector elements after clear() function called:\n";
   var_dump($collection);
?>

Output

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

Vector elements are:
object(Ds\Vector)#1 (4) {
  [0]=>
  string(5) "Mango"
  [1]=>
  string(5) "Apple"
  [2]=>
  string(6) "Banana"
  [3]=>
  string(6) "Orange"
}
Vector elements after clear() function called:
object(Ds\Vector)#1 (0) {
}

Example 2

The following is another example of the PHP Ds\Collection::clear() function. We use this function to remove all the elements of this vector (collection) ([121, 272, 31, 26, 99, 81]) −

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

Output

The above program produces the following output −

Vector elements initial:
Ds\Vector Object
(
)
After adding elements to this collection:
Ds\Vector Object
(
    [0] => 121
    [1] => 272
    [2] => 31
    [3] => 26
    [4] => 99
    [5] => 81
)
After the clear() function called:
Is the collection is empty? bool(true)

Example 3

Let's create another collection named set([]) and use the same clear() function to make it empty by removing all elements from it −

<?php 
   $set = new \Ds\Set();
   $set->add('Sunday');
   $set->add('Monday');
   $set->add('Tuesday');
   $set->add('Wednesday');
   $set->add('Thursday');
   $set->add('Friday');
   $set->add('Saturday');
   echo "Set elements are: \n";
   print_r($set);
   #using clear() function
   $set->clear();
   echo "After clear() function called: \n";
   $res = $set->isEmpty();
   echo "Is the collection is empty? ";
   var_dump($res);
?>

Output

Once the above program is executed, it displays the output as follows:

Set elements are:
Ds\Set Object
(
    [0] => Sunday
    [1] => Monday
    [2] => Tuesday
    [3] => Wednesday
    [4] => Thursday
    [5] => Friday
    [6] => Saturday
)
After clear() function called:
Is the collection is empty? bool(true)