PHP | Ds\Set filter() Function

The Ds\Set::filter() function is an inbuilt function in PHP which is used to create new set using filter function.

Syntax:

Ds\Set public Ds\Set::filter( $callback )

Parameters: This function accepts single parameter $callback which is optional and it returns True if the value should be included, False otherwise.

Return value: This function returns a new set containing all the values for which either the callback returned True or all values that convert to True if a callback was not provided.

Below programs illustrate the Ds\Set::filter() function in PHP:

Program 1:

<?php

// Create new set
$set = new \Ds\Set([10, 20, 30, 40, 50]);

// Display new set using filter function
var_dump($set->filter(function($val) {
    return $val % 4 == 0;
}));

?>

Output:

object(Ds\Set)#3 (2) {
  [0]=>
  int(20)
  [1]=>
  int(40)
}

Program 2:

<?php

// Create new set
$set = new \Ds\Set([2, 5, 4, 8, 3, 9]);

// Display new set using filter function
var_dump($set->filter(function($val) {
    return $val;
}));

?>

Output:

object(Ds\Set)#3 (6) {
  [0]=>
  int(2)
  [1]=>
  int(5)
  [2]=>
  int(4)
  [3]=>
  int(8)
  [4]=>
  int(3)
  [5]=>
  int(9)
}

Reference: https://www.php.net/manual/en/ds-set.filter.php