How to Add Element(s) to the Beginning of an Array in PHP?

Problem:

You have an array(ex. the following one) which has all even numbers as values. Now, you want to a new item(suppose 2) in the first position of the array.

<?php
$even_nos = array(4, 6, 8, 10, 12, 14, 16);
?>

 

Solution:

You can use array_unshift() function to prepend 2 in the beginning of the above array. Let’s see how in the following example –

<pre>
<?php
$even_nos = array(4, 6, 8, 10, 12, 14, 16);
array_unshift($even_nos, 2);
print_r($even_nos);
?>
</pre>

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Output:

Array
(   
    [0] => 2   
    [1] => 4   
    [2] => 6   
    [3] => 8   
    [4] => 10   
    [5] => 12   
    [6] => 14   
    [7] => 16
)

How it works:

Line 3	The array $even_nos contains some even numbers. We’ll add 2 in the first index of this array.
Line 4	array_shift() function takes the $even_nos array in its first parameter and the 2 as its second parameter which we want to add in the first index of the $even_no array. The function adds 2 in the array and returns it.
Line 5	Here we print the array.

 

array_unshift() also allows to prepend multiple items at a time

The following example prepends 1, 2, and 3 in the beginning of the $number array-

<pre>
<?php
$numbers = array(4, 5, 6, 7, 8, 9, 10);
array_unshift($numbers, 1, 2, 3);
print_r($numbers);
?>
</pre>

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Output:

Array
(   
    [0] => 1   
    [1] => 2   
    [2] => 3   
    [3] => 4   
    [4] => 5   
    [5] => 6   
    [6] => 7   
    [7] => 8   
    [8] => 9   
    [9] => 10
)

 Things to remember about array_unshift() array

• In the order you write multiple items those are to be added inside the array_unshift() array, the order those elements will be prepended in the array. See the second example above·
• If the supplied array is an indexed array, after prepending new element(s) the keys of the supplied array are modified and serialized from 0. See examples above example.
• If the supplied array is an associative array, after prepending new item(s) the keys of the associative array will not be changed. See the example below-

  <pre>
  <?php
  $numbers = array("first"=>4, "second"=>5, "third"=>6);
  array_unshift($numbers, 1, 2, 3);
  print_r($numbers);
  ?>
  </pre>
  

  
  Output:

  Array
  (
      [0] => 1
      [1] => 2
      [2] => 3
      [first] => 4
      [second] => 5
      [third] => 6
  )

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