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.

1 2 3

<?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 –

1 2 3 4 5 6 7

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

Output:

1 2 3 4 5 6 7 8 9 10 11

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-

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

Output:

1 2 3 4 5 6 7 8 9 10 11 12 13

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-

  1 2 3 4 5 6 7

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

  
  Output:
  1 2 3 4 5 6 7 8 9

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