Question

I’m trying to create an associative array like this:

$key = '0'
$arr = array((string)$key=>$value);

Later, checking is_string(array_keys($arr)[0]) returns false.

The casting didn’t help, using ” instead of ‘ didn’t help.

Am I doing something wrong, or is there another way around this, or is it impossible to have a numeric string array key?

Answer 1

PHP handles indexes of arrays in a bit more special way than just assigning to variables. Rules are clearly written in manual. Here is excerpt regarding your question.

A key may be either an integer or a string. If a key is the standard representation of an integer, it will be interpreted as such (i.e. “8” will be interpreted as 8, while “08” will be interpreted as “08”). Floats in key are truncated to integer. The indexed and associative array types are the same type in PHP, which can both contain integer and string indices.

Quote from
http://php.net/manual/en/language.types.array.php