PHP - 如何解析外部URL以查找未知的get参数

Question

I'm trying to create a script that can find and identify an Amazon Affiliate ID from the URL.

I know the Affiliate ID appears after the parameter "&tag=" but it's location in the URL is not always consistent. Sometimes it's in the middle:

http://www.amazon.com/gp/goldbox?&tag=adamcarolla09-20&camp=217705&creative=406565&linkCode=ur1&adid=1S1WPEJM5M1Y1RRW2875&

Sometimes it's at the end:

http://www.amazon.com/?_encoding=UTF8&camp=1789&creative=9325&linkCode=ur2&tag=schlockmercenary

How can I write a script that goes through the URL and returns just the tag, regardless of it's position in the string?

Answer 1

You can use PHP parse str:

<?php
    // ...
    parse_str($url, $output);
    echo $output['tag'];
?>