How to Extract Array Elements Based on Key Prefixes in PHP?

Keeping Only Array Elements with Specific Key Prefixes

Consider an array with keys prefixed with a specific string, such as "foo-". Removing all elements with keys not matching this prefix can be achieved using various approaches.

Functional Approach

<code class="php">$array = array_filter($array, function($key) {
    return strpos($key, 'foo-') === 0;
}, ARRAY_FILTER_USE_KEY);</code>

Procedural Approach

<code class="php">$only_foo = array();
foreach ($array as $key => $value) {
    if (strpos($key, 'foo-') === 0) {
        $only_foo[$key] = $value;
    }
}</code>

Object-Oriented Procedural Approach

<code class="php">$i = new ArrayIterator($array);
$only_foo = array();
while ($i->valid()) {
    if (strpos($i->key(), 'foo-') === 0) {
        $only_foo[$i->key()] = $i->current();
    }
    $i->next();
}</code>

These approaches allow you to retain only the elements from the original array that have keys beginning with the specified string.

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