How can I force PHP to use strings for array keys?

In PHP, array keys that look like integers are automatically cast to integers, while non-numeric keys are stored as strings. Because PHP's internal array storage inherently treats numeric keys as integers, you cannot change the type of an existing key. To force all keys to be strings, you must create a new array and explicitly cast the keys during iteration:

Example of explicitly casting array keys to strings in PHP

<‌?php

$array = array("first" => "value1", 2 => "value2");
$new_array = array();
foreach ($array as $key => $value) {
    $new_array[(string) $key] = $value;
}

print_r($new_array);

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This will preserve all values while ensuring every key is stored as a string.

Another approach is to serialize the array to JSON and decode it back. JSON only supports string keys, so this method automatically converts all keys to strings. Note that this approach is less efficient for large arrays due to serialization overhead:

Example of using json_encode() and json_decode functions with assoc option set to true to force PHP to use strings for array keys

<‌?php

$array = array("first" => "value1", 2 => "value2");
$json = json_encode($array);
$new_array = json_decode($json, true);

print_r($new_array);

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Please note that json_encode will convert non-string keys to strings as well.