How to Efficiently Prepend a Prefix to Array Keys in PHP?

Prepending a Prefix to Array Keys Efficiently

When manipulating arrays, it's often necessary to add a prefix to all keys. This operation can be performed in several ways, but not all approaches are equally efficient.

Fastest Solution

The fastest solution is to use array_combine() in conjunction with array_map():

<code class="php">$prefix = "prefix";
$array = array_combine(
    array_map(fn($k) => $prefix . $k, array_keys($array)),
    $array
);</code>

This method iterates over the original array keys, appends the prefix, and creates a new array using array_combine() to reassign the keys and values accordingly.

Other Solutions

Other solutions include:

• Using a foreach loop to iterate over each key and manually append the prefix, followed by unsetting the original key:

<code class="php">foreach ($array as $k => $v)
{
    $array[$prefix . $k] = $v;
    unset($array[$k]);
}</code>

• Utilizing a custom KeyPrefixer class with an __construct() method and mapArray() method for efficiently performing the prefix operation:

<code class="php">$prefix = "prefix";
$array = KeyPrefixer::prefix($array, $prefix);</code>

Historical Perspective

Prior to PHP 5.3, a different approach was necessary:

<code class="php">$prefixer = new KeyPrefixer($prefix);
return $prefixer->mapArray($array);</code>

This method utilized a custom class and array_map() with an anonymous function to manipulate the keys and values.

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