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

YOU CAN’T!!

Strings containing valid integers will be cast to the integer type. E.g. the key “8” will actually be stored under 8. On the other hand “08” will not be cast, as it isn’t a valid decimal integer.

Edit:

ACTUALLY YOU CAN!!
Cast sequential array to associative array

$obj = new stdClass;
foreach($array as $key => $value){
    $obj->{$key} = $value;
}
$array = (array) $obj;

In most cases, the following quote is true:

Strings containing valid integers will be cast to the integer type. E.g. the key “8” will actually be stored under 8. On the other hand “08” will not be cast, as it isn’t a valid decimal integer.

This examples from the PHP Docs

 <?php
    $array = array(
        1    => "a",
        "1"  => "b",
        1.5  => "c",
        true => "d",
    );
    var_dump($array);
?>

The above example will output:

array(1) {
  [1]=> string(1) "d"
}

So even if you were to create an array with numbered keys they would just get casted back to integers.

Unfortunately for me I was not aware of this until recently but I thought I would share my failed attempts.

Failed attempts

$arr = array_​change_​key_​case($arr); // worth a try. 

Returns an array with all keys from array lowercased or uppercased. Numbered indices are left as is.

My next attempts was to create a new array by array_combineing the old values the new (string)keys.

I tried several ways of making the $keys array contain numeric values of type string.

range("A", "Z" ) works for the alphabet so I though I would try it with a numeric string.

$keys = range("0", (string) count($arr) ); // integers

This resulted in an array full of keys but were all of int type.

Here’s a couple of successful attempts of creating an array with the values of type string.

$keys = explode(',', implode(",", array_keys($arr))); // values strings

$keys = array_map('strval', array_keys($arr)); // values strings

Now just to combine the two.

$arr = array_combine( $keys, $arr); 

This is when I discovered numeric strings are casted to integers.

$arr = array_combine( $keys, $arr); // int strings
//assert($arr === array_values($arr)) // true. 

The only way to change the keys to strings and maintain their literal values would be to prefix the key with a suffix it with a decimal point "00","01","02" or "0.","1.","2.".

You can achieve this like so.

$keys = explode(',', implode(".,", array_keys($arr)) . '.'); // added decimal point 
$arr = array_combine($keys, $arr);

Of course this is less than ideal as you will need to target array elements like this.

$arr["280."]   

I’ve created a little function which will target the correct array element even if you only enter the integer and not the new string.

function array_value($array, $key){

    if(array_key_exists($key, $array)){
        return $array[ $key ];
    }
    if(is_numeric($key) && array_key_exists('.' . $key, $array)){
        return $array[ '.' . $key ];
    } 
    return null;
}

Usage

echo array_value($array, "208"); // "abc"

Edit:

ACTUALLY YOU CAN!!
Cast sequential array to associative array

All that for nothing