Insert items at beginning of an array in PHP

This post will discuss how to insert items at the beginning of an array in PHP.

1. Using `array_unshift()` function

A simple and efficient solution is to use the array_unshift() function, which prepends one or more elements to the beginning of an array while maintaining the order of the prepended elements.

Following is a simple example demonstrating usage of this function for numerical key array:

<?php

$arr = ['a', 'b', 'c'];

$item = 'd';

array_unshift($arr , $item);

print_r($arr);

/* Output:

Array

(

[0] => d

[1] => a

[2] => b

[3] => c

)

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Note that the numerical keys in the array are re-indexed starting with zero. However, the literal keys won’t be changed, as demonstrated below:

<?php

$arr = ['b' => 'two', 'c' => 'three'];

$item = 'one';

array_unshift($arr, $item);

print_r($arr);

/* Output:

Array

(

[0] => one

[b] => two

[c] => three

)

Download Run Code

2. Using `array_splice()` function

Alternatively, you can use the array_splice() function, which replaces a part of an array with the elements of the specified array.

Here’s an example of its usage to insert an element at the specified position in an array:

<?php

$arr = ['b', 'c'];

$pos = 0;

$item = 'a';

array_splice($arr, $pos, 0, $item);

print_r($arr);

/* Output:

Array

(

[0] => a

[1] => b

[2] => c

)

Download Run Code

Note that, like array_unshift() function, array_splice() does not preserve numeric keys.

<?php

$arr = ['one', 'b' => 'two', 'c' => 'three'];

$pos = 0;

$item = 'zero';

array_splice($arr, $pos, 0, $item);

print_r($arr);

/* Output:

Array

(

[0] => zero

[1] => one

[b] => two

[c] => three

)

Download Run Code

3. Using `+` operator

In some cases, the above functions do not work since they always re-index the array. If you need to prepend an item to an array without re-indexing the keys or need to prepend a key-value pair to an associative array, you can + operator:

<?php

$arr = ['b' => 'two', 'c' => 'three'];

$item = array('a' => 'one');

$arr = $item + $arr;

print_r($arr);

/* Output:

Array

(

[a] => one

[b] => two

[c] => three

)

Download Run Code

This however creates a new array and doesn’t modify the array in-place.

4. Using `array_reverse()` function

Another plausible way to insert an item at the beginning of an associative array is to reverse the array, insert a key and value pair using the $arr[$key] = $val syntax, and then reverse it back to get the desired order.

This approach is demonstrated below:

<?php

$arr = ['b' => 'two', 'c' => 'three'];

$arr = array_reverse($arr);

$arr['a'] = 'one';

$arr = array_reverse($arr);

print_r($arr);

/* Output:

Array

(

[a] => one

[b] => two

[c] => three

)

Download Run Code

Like the + operator, this doesn’t modify the array in-place and creates a new array instead.

That’s all about inserting items at the beginning of an array in PHP.

Insert items at beginning of an array in PHP

1. Using array_unshift() function

2. Using array_splice() function

3. Using + operator

4. Using array_reverse() function

Share this:

1. Using `array_unshift()` function

2. Using `array_splice()` function

3. Using `+` operator

4. Using `array_reverse()` function