PHP URL Validation Functions

Bear in mind that both methods have their own strengths and weaknesses. These will be examined thoroughly in this article. The objective of this article is to recommend the best possible way of validating URLs based on available choices and results.

The Validation Functions to be Evaluated

Searching Google for "validating URL PHP" or "PHP URL validation" (without quotes) yields the following six result,s which any developer can use and integrate into their own application:

#1. Source: http://php.net/manual/en/function.preg-match.php 

Validating Function:

<?php
function validateURL($url){
$regex = "((https?|ftp)://)?";  
$regex .= "([a-z0-9+!*(),;?&=$_.-]+(:[a-z0-9+!*(),;?&=$_.-]+)?@)?"; 
$regex .= "([a-z0-9-.]*).([a-z]{2,3})"; 
$regex .= "(:[0-9]{2,5})?";  
$regex .= "(/([a-z0-9+$_-].?)+)*/?";  
$regex .= "(?[a-z+&$_.-][a-z0-9;:@&%=+/$_.-]*)?";  
$regex .= "(#[a-z_.-][a-z0-9+$_.-]*)?";  
if(preg_match("/^$regex$/", $url)) 
{ 
echo $url."&nbsp;&nbsp;&nbsp;=".'<font color="blue">Valid URL</font>'; 
} 
else {
echo $url."&nbsp;&nbsp;&nbsp;=".'<font color="red">Invalid URL</font>';
}
}
?>

#2. Source: http://phpcentral.com/208-url-validation-in-php.html

Validating Function:

<?php
function validateURL($url){
$regex = "|^http(s)?://[a-z0-9-]+(.[a-z0-9-]+)*(:[0-9]+)?(/.*)?$|i";  
if(preg_match($regex, $url)) 
{ 
echo $url."&nbsp;&nbsp;&nbsp;=".'<font color="blue">Valid URL</font>'; 
} 
else {
echo $url."&nbsp;&nbsp;&nbsp;=".'<font color="red">Invalid URL</font>';
}
}
?>

#3. Source:  http://www.blog.highub.com/regular-expression/php-regex-regular-expression/php-regex-validating-a-url/

Validating Function:

<?php
function validateURL($url){
$regex ="/^(([w]+:)?//)?(([dw]|%[a-fA-fd]{2,2})+(:([dw]|%[a-fA-fd]{2,2})+)?@)?([dw][-dw]{0,253}[dw].)+[w]{2,4}(:[d]+)?(/([-+_~.dw]|%[a-fA-fd]{2,2})*)*(?(&amp;?([-+_~.dw]|%[a-fA-fd]{2,2})=?)*)?(#([-+_~.dw]|%[a-fA-fd]{2,2})*)?$/";  
if(preg_match($regex, $url)) 
{ 
echo $url."&nbsp;&nbsp;&nbsp;=".'<font color="blue">Valid URL</font>'; 
} 
else {
echo $url."&nbsp;&nbsp;&nbsp;=".'<font color="red">Invalid URL</font>';
}
}
?>

#4. Source: Pyro: http://www.webdeveloper.com/forum/archive/index.php/t-11290.html

Validating Function:

<?php
function validateURL($url){
$regex = "/^(http(s?)://|ftp://{1})((w+.){1,})w{2,}$/i";  
if(preg_match($regex, $url)) 
{ 
echo $url."&nbsp;&nbsp;&nbsp;=".'<font color="blue">Valid URL</font>'; 
} 
else {
echo $url."&nbsp;&nbsp;&nbsp;=".'<font color="red">Invalid URL</font>';
}
}
?>

#5. Source: http://php.net/, filter validate URL function: http://php.net/manual/en/filter.filters.validate.php

Validating Function:

<?php
function validateURL($url){
if(filter_var($url, FILTER_VALIDATE_URL))
{ 
echo $url."&nbsp;&nbsp;&nbsp;=".'<font color="blue">Valid URL</font>'; 
} 
else {
echo $url."&nbsp;&nbsp;&nbsp;=".'<font color="red">Invalid URL</font>';
}
}
?>

#6. Source: http://stackoverflow.com/questions/206059/php-validation-regex-for-url

<?php
function validateURL($url){
$regex = "#((http|https|ftp)://(S*?.S*?))(s|;|)|]|[|{|}|,|"|'|:|<|$|.s)#ie";  
if(preg_match($regex, $url)) 
{ 
echo $url."&nbsp;&nbsp;&nbsp;=".'<font color="blue">Valid URL</font>'; 
} 
else {
echo $url."&nbsp;&nbsp;&nbsp;=".'<font color="red">Invalid URL</font>';
}
}
?>

The URLs to be Tested

Below are the URLs to be tested against the above URL validating functions.

Acceptable URLs (one URL per line):

http://www.example.org
http://www.example.org/
www.example.org/
www.example.org
example.org
subdomain.example.org
https://example.org
https://example.subdomain.org
http://www.example.com/discus/messages/131/24297.html
http://php.net/manual/en/function.preg-match.php
http://www.lgts.com/catalog/product_info.php?products_id=6&osCsid=be3
http://192.168.1.1
http://192.168.1.1/
http://64.233.167.99/
http://siteexplorer.search.yahoo.com/search?p=www.x.com&bwmo=d&bwmf=u
http://www.example.com/2009/01/08/rfc-example-url-validation
http://mp3hungama.com/music/genre_albums.php?id=3
www.enfocus.com/product.php?id=855
http://www.example.com/space%20here.html
http://www.example.com/space here.html
osdir.com/ml/unassigned-bugs/2010-04/msg00162.html
forums.asp.net/p/1157859/1905808.aspx
http://forums.asp.net/p/1157859/1905808.aspx
https://forums.asp.net/p/1157859/1905808.aspx
http://url.com/?source=rss_feed
https://www.sound.com/catalog/account.php?osCsid=07b6922f54ed9674582
https://www.thehayexperts.co.uk/index.php?osCsid=xlo8u8nl8m4t725
ftp://example.com
http://example.com/index.asp
http://www.smallnetbuilder.com/component/option,com_chart/Itemid,189/
http://example.org:80
ftp://asmith@ftp.example.org
HTTP://EN.EXAMPLE.ORG/
HTTP://EXAMPLE.ORG/
HTTP://WWW.EXAMPLE.ORG
http://example.com/redirect?url=http%3A%2F%2Fplanio.com
http://www.example.com:8080
www.linux-rules-the-world.com
http://www.google.com/company_secrets.htm
http://askville.amazon.com/phones/AnswerViewer.do?requestId=7665185

Malformed URLs(one URL per line):

C:forums.asp.net/p/1157859/1905808.aspx
dfds://example.com
http://www.example.com.
http://www.example.com/.
http://.example.com
http://example/
http:///example.com
http://www
htp://www.google.com
http//www.google.com
http://example.com/index.php//
http://example.com//
/newfaq/basic/url.html
http://www.example.commain.html
example.123
http://username:password@hostname/path?arg=value#anchor
.example.
example
http://-example.com
http://example-.com
//example.com.
http://www_google_com
http://www-google-com
http:forums.asp.net/p/1157859/1905808.aspx
http://somedomain.com/ind%ex.html
http://....../path/?query#fragment
http://...../