PHP Cookbook

4.5. Deleting Elements from an Array

Problem

You want to remove one or more elements from an array.

Solution

To delete one element, use unset( ):

unset($array[3]);
unset($array['foo']);

To delete multiple noncontiguous elements, also use unset( ):

unset($array[3], $array[5]);
unset($array['foo'], $array['bar']);

To delete multiple contiguous elements, use array_splice( ):

array_splice($array, $offset, $length);

Discussion

Using these functions removes all references to these elements from PHP. If you want to keep a key in the array, but with an empty value, assign the empty string to the element:

$array[3] = $array['foo'] = '';

Besides syntax, there’s a logical difference between using unset( ) and assigning '' to the element. The first says “This doesn’t exist anymore,” while the second says “This still exists, but its value is the empty string.”

If you’re dealing with numbers, assigning 0 may be a better alternative. So, if a company stopped production of the model XL1000 sprocket, it would update its inventory with:

unset($products['XL1000']);

However, if it temporarily ran out of XL1000 sprockets, but was planning to receive a new shipment from the plant later this week, this is better:

$products['XL1000'] = 0;

If you unset( ) an element, PHP adjusts the array so that looping still works correctly. It doesn’t compact the array to fill in the missing holes. This is what we mean when we say that all arrays are associative, even when they appear to be numeric. Here’s an example:

// create ...