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PHP Ds\Set Functions Complete Reference

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Set is the collection of unique values. The implementation of Ds\Set is similar to the Ds\Map which creates a hash table. The values of Ds\Set are used as key and the mapped values are ignored.

Requirements: PHP 7 is required for both extension and the compatibility polyfill. 

Installation: The easiest way to install data structure by using the PECL extension.

pecl install ds


public Ds\Set::functionName()

Example: Below programs illustrate the Ds\Set::count() function:


// Declare new Set
$set = new \Ds\Set([10, 15, 21]);
// Display the Set element
// Display count of elements
// present in the Set
echo "Count is : ";


object(Ds\Set)#1 (3) {
Count is : 3

Complete list of data structure DS\Set:



add()It is used to add values to the set.
allocate()Allocate memory for required capacity.
capacity()Return the capacity of the set.
clear()Remove all values from the set.
__construct()Create new instance of set.
contains()Check the given value exists in the set or not.
copy()Return the copy of the set element.
count()Count the number of values present in the Set.
diff()Create a set that contains the elements of the first set which are not present in the second set.
filter()Create new set using filter function.
first()Returns the first element of the Set.
get()Get a value from the Set instance. 
intersect()Create a new set that contains the intersection of two sets.
isEmpty()Check whether a set is empty or not.
join()It is used to join all values as string
last()Return the last element from the Set instance.
merge()Returns a set after adding all given values to the set.
reduce()Set to a single value by applying operations using the callback function.
remove()Remove specific values from a Set instance..
reverse()Reverse the order of elements present in the Set instance.
reversed()Create a copy of the original Set with values arranged in reverse order.
slice()Return the sub-set of a given range.
sort()Sort the elements of a specified Set instance according to the values.
sorted()Return a sorted copy of a given set. 
sum()Find the sum of all of the elements present in a Set.
toArray()Convert the Set into an associative array.
union()Create a new set that contains the union of two sets
xor()Create a new set that contains the value either in the first set or second set but not both.
Last Updated : 25 Jan, 2023
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