PHP - Ds\Collection::copy() Function

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The PHPDs\Collection::copy() function is used to create a shallow copy of a current collection such as vector, set, etc.

When this function is invoked on a collection, a shallow copy of that collection is created and the same shallow copy is returned in the output.

A shallow copy of a collection is a copy where the properties share the same references as those of the source object from which the copy was made.

Syntax

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

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

Parameters

This function does not accept any parameter.

Return value

This function returns a collection, which is a shallow copy of the current collection.

Example 1

The following program demonstrates the usage of the PHP Ds\Collection::copy() function −

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

Output

The above program produces the following output −

The original collection elements:
Ds\Vector Object
(
    [0] => 1
    [1] => 2
    [2] => 3
    [3] => 4
    [4] => 5
)
The shallow copy of this original collection is:
object(Ds\Vector)#2 (5) {
  [0]=>
  int(1)
  [1]=>
  int(2)
  [2]=>
  int(3)
  [3]=>
  int(4)
  [4]=>
  int(5)
}

Example 2

Following is another example of the PHP Ds\Collection::copy() function. We use this function to create a shallow copy of this vector(collection) −

<?php 
   $vect = new \Ds\Vector();
   echo "Before adding elements: \n";
   print_r($vect);
   $vect->push(121);
   $vect->push(272);
   $vect->push(31);
   $vect->push(26);
   $vect->push(99);
   $vect->push(81);
   echo "After adding elements: \n";
   print_r($vect);
   #using copy() function
   $res = $vect->copy();
   echo "The shallow copy of this original collection is: \n";
   print_r($res);
?>

Output

After executing the above program, it generates the following output −

Before adding elements:
Ds\Vector Object
(
)
After adding elements:
Ds\Vector Object
(
    [0] => 121
    [1] => 272
    [2] => 31
    [3] => 26
    [4] => 99
    [5] => 81
)
The shallow copy of this original collection is:
Ds\Vector Object
(
    [0] => 121
    [1] => 272
    [2] => 31
    [3] => 26
    [4] => 99
    [5] => 81
)

Example 3

Let's create another collection named set([]) and use the same copy() function to create a shallow of this set (['Sunday', 'Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday', 'Saturday']) −

<?php 
   $set = new \Ds\Set();
   $set->add('Sunday');
   $set->add('Monday');
   $set->add('Tuesday');
   $set->add('Wednesday');
   $set->add('Thursday');
   $set->add('Friday');
   $set->add('Saturday');
   echo "Original set elements are: \n";
   print_r($set);
   #using copy() function
   $res = $set->copy();
   echo "The shallow copy of this original collection is: \n";
   print_r($res);
?>

Output

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

Original set elements are:
Ds\Set Object
(
    [0] => Sunday
    [1] => Monday
    [2] => Tuesday
    [3] => Wednesday
    [4] => Thursday
    [5] => Friday
    [6] => Saturday
)
The shallow copy of this original collection is:
Ds\Set Object
(
    [0] => Sunday
    [1] => Monday
    [2] => Tuesday
    [3] => Wednesday
    [4] => Thursday
    [5] => Friday
    [6] => Saturday
)

Example 4

In the example below, we use the PHP Ds\Collection::copy() to create a shallow copy to this vector (collection) (["test_string", 1525, false]) −

<?php
   $seq = new \Ds\Vector(["test_string", 1525, false]);
   echo "Original vector elements are: \n";
   print_r($seq);
   $res = $seq->copy();
   echo "The shallow copy of this original collection is: \n";
   var_dump($res);	
?>

Output

On executing the above program, it displays the following output:

Original vector elements are:
Ds\Vector Object
(
    [0] => test_string
    [1] => 1525
    [2] =>
)
The shallow copy of this original collection is:
object(Ds\Vector)#2 (3) {
  [0]=>
  string(11) "test_string"
  [1]=>
  int(1525)
  [2]=>
  bool(false)
}