In PHP, how do you change the key of an array element?

Question

I have an associative array in the form key => value where key is a numerical value, however it is not a sequential numerical value. The key is actually an I

Answer 1

Easy stuff:

this function will accept the target $hash and $replacements is also a hash containing newkey=>oldkey associations.

This function will preserve original order, but could be problematic for very large (like above 10k records) arrays regarding performance & memory.

function keyRename(array $hash, array $replacements) {
    $new=array();
    foreach($hash as $k=>$v)
    {
        if($ok=array_search($k,$replacements))
            $k=$ok;
        $new[$k]=$v;
    }
    return $new;    
}

this alternative function would do the same, with far better performance & memory usage, at the cost of loosing original order (which should not be a problem since it is hashtable!)

function keyRename(array $hash, array $replacements) {

    foreach($hash as $k=>$v)
        if($ok=array_search($k,$replacements))
        {
          $hash[$ok]=$v;
          unset($hash[$k]);
        }

    return $hash;       
}