PHP array_shift Function | Remove From Beginning From Array

PHP array_shift is an inbuilt Function in PHP. It removes an element from the beginning of the array and returns it. Also, if the keys of the array are numerical, it re-indexes the remaining elements again from 0. However, it does not change literal keys. In this article, we will discuss the PHP array_shift Function. Also, we will discuss a few examples of using it.

Syntax

array_shift($array)

Parameters

The array_shift Function in PHP expects only one parameter. The array from which you need to remove the first element is passed as the parameter.

Return Value

The PHP array_shift Function returns the element it shifts from the beginning. However, if the input array is empty or invalid, it returns a NULL value.

Examples

Let’s discuss a few examples of using the PHP array_shift function.

Example 1: Simple Integer Array

For instance, consider a simple array.

<?php
	$testArray = array(1, 2, 3, 4);

	//Original Array
	print_r($testArray);
	/*
	Array
	(
	    [0] => 1
	    [1] => 2
	    [2] => 3
	    [3] => 4
	)
	*/

	$shiftedElement = array_shift($testArray);
	//Shifted Element
	var_dump($shiftedElement);
	//int(1)

	//Reindexed Array
	print_r($testArray);
	/*
	Array
	(
	    [0] => 2
	    [1] => 3
	    [2] => 4
	)
	*/
?>

In the above example you can observe the following:

• The original array contains 4 elements.
• The Function returns the first element from the original array.
• The remaining elements are numerically re-indexed again starting from 0.

Example 2: Associative Array

For example, consider an associative array.

<?php
	$testArray = array('a' => 1, 'b' => 2, 'c' => 3, 'd' => 4);

	//Original Array
	print_r($testArray);
	/*
	Array
	(
	    [a] => 1
	    [b] => 2
	    [c] => 3
	    [d] => 4
	)
	*/

	$shiftedElement = array_shift($testArray);
	//Shifted Element
	var_dump($shiftedElement);
	//int(1)

	//Reindexed Array
	print_r($testArray);
	/*
	Array
	(
	    [b] => 2
	    [c] => 3
	    [d] => 4
	)
	*/
?>

You can observe the following:

• The original array contain 4 elements with string keys.
• The function returns the first element from the original array.
• The function does not change the literal keys of the original array.

Example 3: Multi-Dimensional Array

Similarly, you can also pass multi-dimensional arrays to the function.

<?php
	$testArray = array(
		array('Monica', 'Chandler'),
		array('Chandler'),
		array('Joey')
	);

	$shiftedElement = array_shift($testArray);
	//Shifted Element
	print_r($shiftedElement);
	/*
	Array
	(
	    [0] => Monica
	    [1] => Chandler
	)
	*/

	//Reindexed Array
	print_r($testArray);
	/*
	Array
	(
	    [0] => Array
	        (
	            [0] => Chandler
	        )
	    [1] => Array
	        (
	            [0] => Joey
	        )
	)
	*/
?>

Likewise, the function returns the first element of the original array. Also, it re-arranges all the remaining elements starting from index 0.

Expert Tip

This function is not very fast when it comes to big arrays. This is because, it re-indexes all the elements in the remaining array which takes linear time.

Conclusion

In this article, we discussed the array_shift Function. You can read more about it on the Official PHP Documentation. Also, you can read more about PHP Array Functions on Concatly.