如何在PHP中获取实际的URL？

Question

I have the url http://www.wolframalpha.com/entities/zip_codes/AL_36574/9t/ej/3z/

when you go to this url it go to http://www.wolframalpha.com/input/?i=AL+36574 here.

Now i want this url from the previous one. therefore i created the code like this

<?php
$url="http://www.wolframalpha.com/entities/zip_codes/AL_36574/9t/ej/3z/";
    $headers = get_headers($url, 1);



// will echo http://www.wolframalpha.com/input/?i=AL+36574
echo $headers[0];
?>

but it does not works Plz help me

Answer 1

Curl would be the best way to find out the redirect. I had this code for my own purposes a while ago, it is not my own. You will have to work out the regex yourself.

<?php
$url="http://www.wolframalpha.com/entities/zip_codes/AL_36574/9t/ej/3z/";

$ch = curl_init($url);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, TRUE);
curl_setopt($ch, CURLOPT_HEADER, TRUE); // We'll parse redirect url from header.
curl_setopt($ch, CURLOPT_FOLLOWLOCATION, FALSE); // We want to just get redirect url but not to follow it.
$response = curl_exec($ch);
preg_match_all('^0;url=\'(.*?)[$\']+^', $response, $matches);
curl_close($ch);
echo !empty($matches[1]) ? "http://www.wolframalpha.com".trim($matches[1][0]) : 'No redirect found';
?>

You can see it working here http://viper-7.com/TPqpJ8