PHP和XML - 在文档中设置唯一ID

Question

i have this script example:

while (count($xml->xpath('*[@id="' . $id . '"]/@id')) > 0)
{
    $id = 'example_' . ++$x;
}

But if i check this with 1.000 Childrens in the element, i must wait more than a hour for an response.

How i could quicker check if a id exists?

Thank's in Advance for your Tip!

Answer 1

Thanks @michi:

I modified the example and this is the final answer:

$ids = $xml->xpath('*[@id="' . $id . '"]/@id');
if(count($ids) > 0)
{
    $ids = $xml->xpath('*[starts-with(@id, "example_")]/@id');
    $id = max(array_map(
            function($a)
            {
                list(, $id) = explode('_', $a);
                return intval($id);
            }, $ids)) + 1;
    $id = 'example_' . $id;
}

=}