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Last updated: Thu, 21 Aug 2003

CIV. URL Functions


Dealing with URL strings: encoding, decoding and parsing.


No external libraries are needed to build this extension.


There is no installation needed to use these functions; they are part of the PHP core.

Runtime Configuration

This extension has no configuration directives defined in php.ini.

Resource Types

This extension has no resource types defined.

Predefined Constants

This extension has no constants defined.

Table of Contents
base64_decode -- Decodes data encoded with MIME base64
base64_encode -- Encodes data with MIME base64
get_meta_tags --  Extracts all meta tag content attributes from a file and returns an array
parse_url -- Parse a URL and return its components
rawurldecode -- Decode URL-encoded strings
rawurlencode -- URL-encode according to RFC 1738
urldecode -- Decodes URL-encoded string
urlencode -- URL-encodes string

add a note add a note User Contributed Notes
URL Functions
chemanfit at hotmail
07-Jun-2003 07:24
just a side note to the above you will need to add the ?


ignacio paz posse
13-Mar-2003 09:31
Note on the above: the point is that is that using $_SERVER['QUERY_STRING'] along with $PHP_SELF we will have passed whatever variables are already appended (as they might be needed for database queries)

example, given the following url: http://www.your_domain/somepage.php?variable=1;

using $PHP_SELF" we are passing
[scheme]:(http://), [host]: www.your_domain/  and [path]: somepage.php

adding $_SERVER['QUERY_STRING'], we pass that, plus [query]: variable=1
13-Mar-2003 02:16
May be this is obvious but helps me since I found it:
If I want to append a variable to the url and pass it to the same page. ( in this example I'm using action=email to include an email form on the user click) i do:

// ...

<a href="<? echo $PHP_SELF,'?',$_SERVER['QUERY_STRING'],'&action=email' ?>">email to us</a>

// ...

/* somewhere in the the page (in my case at the bottom) I have: */

<? if ($action=='email') include('emailForm.htm'); ?>
jrg45 at pantheon dot yale dot edu
11-Jul-2002 04:14
Note that $_SERVER["HTTP_REFERER"] may not include GET data that was included in the referring address, depending on the browser.  So if you rely on GET variables to generate a page, it's not a good idea to use HTTP_REFERER to smoothly "bounce" someone back to the page he/she came from.
postmaster at asmatic dot ch
29-Apr-2002 11:15
If you want to get the filename requested on a global error page like a 404, just use this code...

// get the full var...

// part[1] is the url...
// part[0] is the http code (404, etc).
if(strpos($page,";")>0) {
   $pageParts = explode(";",$page);
   $page = $pageParts[1];

// get only the filename...
$page = basename($page);
stephane-wantiez at tiscalinet dot be
07-Feb-2002 10:29
if you do this, it will be easier :
echo "http://{$HTTP_HOST}{$REQUEST_URI}";
verdy_p at wanadoo dot fr
27-May-2001 12:47
Note also that the URL shown in $HTTP_REFERER is not always the URL of the web page where the user clicked to invoke the PHP script.
This may instead be a document of your own web site, which contains an HTML element whose one attribute references the script. Note also that the current page fragment (#anchor) may be transmitted or not with the URL, depending on the browser.
<FRAME src="your-page-script.php"8>
<IMAGE src="your-image-script.php">

In such case, browsers should transmit the URL of the container document, but some still persist in using the previous document in the browser history, and this could cause a different $HTTP_REFERER value be sent when the user comes back to the document referencing your script. If you wanna be sure that the actual current document or previous document in the history is sent, use client-side JavaScript to send it to your script:

<SCRIPT language="JavaScript"><!--
document.writeln('<FRAME src="your-page-script.php?js=1&amp;ref=' +
document.location + '">');
<FRAME src="your-page-script.php?js=0">

And then check the value of $js in your page script to generate appropriate content when the remote user agent does not support client-side scripts (such as most index/scan robots, some old or special simplified browsers, or browsers with JavaScript disabled by their users).
verdy_p at wanadoo dot fr
26-May-2001 11:55
Warning: when the PHP engine runs for your hosted web site, it may execute on a domain name which is completely different than the one the user requested in its browser. Many free web hosting site use proxies and/or multiple DNS entries for your hosted web site. This means that:
- the IP of the web server can change if multiple DNS entries are present (there may be several web servers running concurrently)
- reverse DNS name from the IP may give different domain name over time, or if the domain name is a CNAME only for a virtual web server hosting many domains
- the server running PHP may be different than the web server
- the web server may be hidden behind a proxy which balances the load between a farm of servers
- the queried host name in the HTTP headers may be different than the queried host name in the browser, if behind a redirecting proxy
- the actual path name of the ressource may be also different, with additional path elements: this is very common on free hosting servers, where you get a virtual CNAME domain, which gets translated by a proxy into an actual web server, and a domain-specific document root directory

So when thinking about using absolute path names you can retreive from PHP, beware that this may not be accurate to insert as absolute URL's in the HTML code built with PHP.

The best solution is then to ALWAYS USE relative URLs to reference documents and form scripts on your local server !

This applies to $PHP_SELF too, because it's an absolute pathname: don't use it directly but you can safely use basename($PHP_SELF) to reference your script within HTML forms:

<FORM method="GET" action="$self">
cgmckeever at yahoo dot com
19-Aug-2000 07:20
$HTTP_HOST still grabs the redirected server name.

jphilbin at portcitymail dot com
19-Aug-2000 02:56
To get the full url of what should be currently
in a users browser, try this:
$url = sprintf("%s%s%s","http://",$HTTP_HOST,$REQUEST_URI);
echo "$url";
tumor at kkt dot bme dot hu
02-Apr-2000 01:18
To check if a URL is valid, try to fopen() it. If fopen() results an error (returns false), then PHP cannot open the URL you asked. This is usually because it is not valid...

 Last updated: Thu, 21 Aug 2003
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