PHP: How to resolve a relative url

Question

I need a function that given a relative URL and a base returns an absolute URL. I've searched and found many functions that do it different ways.

resolve("../abc.png", "http://example.com/path/thing?foo=bar") # returns http://example.com/abc.png 

Is there a canonical way?

On this site I see great examples for python and c#, lets get a PHP solution.

Answer 1

Perhaps this article could help?

http:// nashruddin.com/PHP_Script_for_Converting_Relative_to_Absolute_URL

Edit: reproduced code below for convenience

<?php     function rel2abs($rel, $base)     {         /* return if already absolute URL */         if (parse_url($rel, PHP_URL_SCHEME) != '' || substr($rel, 0, 2) == '//') return $rel;          /* queries and anchors */         if ($rel[0]=='#' || $rel[0]=='?') return $base.$rel;          /* parse base URL and convert to local variables:          $scheme, $host, $path */         extract(parse_url($base));          /* remove non-directory element from path */         $path = preg_replace('#/[^/]*$#', '', $path);          /* destroy path if relative url points to root */         if ($rel[0] == '/') $path = '';          /* dirty absolute URL */         $abs = "$host$path/$rel";          /* replace '//' or '/./' or '/foo/../' with '/' */         $re = array('#(/\.?/)#', '#/(?!\.\.)[^/]+/\.\./#');         for($n=1; $n>0; $abs=preg_replace($re, '/', $abs, -1, $n)) {}          /* absolute URL is ready! */         return $scheme.'://'.$abs;     } ?>