I have the following code :
function removeFilename($url)
{
$file_info = pathinfo($url);
return isset($file_info['extension'])
? str_replace($file_info['filename'] . "." . $file_info['extension'], "", $url)
: $url;
}
$url1 = "http://website.com/folder/filename.php";
$url2 = "http://website.com/folder/";
$url3 = "http://website.com/";
echo removeFilename($url1); //outputs http://website.com/folder/
echo removeFilename($url2);//outputs http://website.com/folder/
echo removeFilename($url3);//outputs http:///
Now my problem is that when there is only only a domain without folders or filenames my function removes website.com too.
My idea is there is any way on php to tell my function to do the work only after third slash or any other solutions you think useful.
UPDATED : ( working and tested )
<?php
function removeFilename($url)
{
$parse_file = parse_url($url);
$file_info = pathinfo($parse_file['path']);
return isset($file_info['extension'])
? str_replace($file_info['filename'] . "." . $file_info['extension'], "", $url)
: $url;
}
$url1 = "http://website.com/folder/filename.com";
$url2 = "http://website.org/folder/";
$url3 = "http://website.com/";
echo removeFilename($url1); echo '<br/>';
echo removeFilename($url2); echo '<br/>';
echo removeFilename($url3);
?>
Output:
http://website.com/folder/
http://website.org/folder/
http://website.com/
Sounds like you are wanting to replace a substring and not the whole thing. This function might help you:
http://php.net/manual/en/function.substr-replace.php
Since filename is at last slash you can use substr and str_replace to remove file name from path.
$PATH = "http://website.com/folder/filename.php";
$file = substr( strrchr( $PATH, "/" ), 1) ;
echo $dir = str_replace( $file, '', $PATH ) ;
OUTPUT
http://website.com/folder/
pathinfo cant recognize only domain and file name. But if without filename url is ended by slash
$a = array(
"http://website.com/folder/filename.php",
"http://website.com/folder/",
"http://website.com",
);
foreach ($a as $item) {
$item = explode('/', $item);
if (count($item) > 3)
$item[count($item)-1] ='';;
echo implode('/', $item) . "\n";
}
result
http://website.com/folder/
http://website.com/folder/
http://website.com
Close to the answer of splash58
function getPath($url) {
$item = explode('/', $url);
if (count($item) > 3) {
if (strpos($item[count($item) - 1], ".") === false) {
return $url;
}
$item[count($item)-1] ='';
return implode('/', $item);
}
return $url;
}
I have a string which contains a url. I am trying to extract the url from the additional text in the most efficient way. So far I have been using explode but I have to explode twice and then rebuild the url. Regex is not something I dominate yet so i placed it out of the question(unless it is the best solution). Is there a way to extract the url in one step?
$url = "/url?q=http://www.somesite.com/sites/pages/page?id=1545778&sa=U&ei=EhHLVL_yJcb-yQSZ7oDgAg&ved=0CBMQFjAA&usg";
$strip1 = explode( '&', $url );
$strip2 = explode('=', $strip1[0]);
$result = $strip2[1].'='.$strip2[2];
result:
http://www.somesite.com/sites/pages/page?id=1545778
Try like this:use preg_split()
$date = "/url?q=http://www.somesite.com/sites/pages/page?id=1545778&sa=U&ei=EhHLVL_yJcb-yQSZ7oDgAg&ved=0CBMQFjAA&usg";
$t =preg_split("/[=&]/", $date);
echo $t[1]."=".$t[2]; //output: http://www.somesite.com/sites/pages/page?id1545778
$strip1 = explode( '/url?q=', $url );
Use this regex $strip1
^((http):\/)?\/?([^:\/\s]+)((\/\w+)*\/)([\w\-\.]+[^#?\s]+)(.*)?(#[\w\-]+)?$
you will get an array of sections in the url
Ugly one-step regex-free solution.
$url = "/url?q=http://www.somesite.com/sites/pages/page?id=1545778&sa=U&ei=EhHLVL_yJcb-yQSZ7oDgAg&ved=0CBMQFjAA&usg";
$result = substr( $url, strpos( $url, '=' ) + 1, strpos( $url, '&' ) - strpos( $url, '=' ) - 1 );
echo $result;
And cleaner two-step variation.
$url = "/url?q=http://www.somesite.com/sites/pages/page?id=1545778&sa=U&ei=EhHLVL_yJcb-yQSZ7oDgAg&ved=0CBMQFjAA&usg";
$start = strpos( $url, '=' ) + 1;
$result = substr( $url, $start, strpos( $url, '&' ) - $start );
echo $result;
Somewhat less-ugly regex solution.
$url = "/url?q=http://www.somesite.com/sites/pages/page?id=1545778&sa=U&ei=EhHLVL_yJcb-yQSZ7oDgAg&ved=0CBMQFjAA&usg";
$result = preg_replace( '/[^=]*=([^&]*).*/', '${1}', $url );
echo $result;
Both produce the following output.
http://www.somesite.com/sites/pages/page?id=1545778
Technically, that second ? in the URL should be URL encoded, but we can get around that. Use parse_url to get the query, then replace ? with a URL encoded version using str_replace. After this, you will have a valid query that you can parse using parse_str.
$query = parse_url($url, PHP_URL_QUERY);
$query = str_replace("?", urlencode("?"), $query);
parse_str($query, $params);
echo $params['q'];
// displays http://www.somesite.com/sites/pages/page?id=1545778
$url = "/url?q=http://www.somesite.com/sites/pages/page?id=1545778&sa=U&ei=EhHLVL_yJcb-yQSZ7oDgAg&ved=0CBMQFjAA&usg";
$strip3 = current(explode('&',end(explode('=', $url,2))));
print_r ($strip3); //output http://www.somesite.com/sites/pages/page?id=1545778
In the preg_match below, I'm comparing against two static strings, $url and $my_folder...
$url = get_bloginfo('url')
//$url = 'http://site.com'
$my_folder = get_option('my_folder');
//$my_folder = 'http://site.com/somefolder;
I'm getting a match when the $my_folder string has a trailing slash
http://somefolder/go/
But this does not create a match...
http://somefolder/go
However, another problem is that this also matches...
http://somefolder/gone
Code is...
$my_folder = get_option('rseo_nofollow_folder');
if($my_folder !=='') $my_folder = trim($my_folder,'/');
$url = trim(get_bloginfo('url'),'/');
preg_match_all('~<a.*>~isU',$content["post_content"],$matches);
for ( $i = 0; $i <= sizeof($matches[0]); $i++){
if($my_folder !=='')
{
//HERES WHERE IM HAVING PROBLEMS
if ( !preg_match( '~nofollow~is',$matches[0][$i])
&& (preg_match('~' . $my_folder . '/?$~', $matches[0][$i])
|| !preg_match( '~'. $url .'/?$~',$matches[0][$i])))
{
$result = trim($matches[0][$i],">");
$result .= ' rel="nofollow">';
$content["post_content"] = str_replace($matches[0][$i], $result, $content["post_content"]);
}
}
else
{
//THIS WORKS FINE, NO PROBLEMS HERE
if ( !preg_match( '~nofollow~is',$matches[0][$i]) && (!preg_match( '~'.$url.'~',$matches[0][$i])))
{
$result = trim($matches[0][$i],">");
$result .= ' rel="nofollow">';
$content["post_content"] = str_replace($matches[0][$i], $result, $content["post_content"]);
}
}
}
return $content;
~^http://somefolder/go(?:/|$)~
You need to first remove the trailing slash and add '/?' at the end of your regexp
$my_folder = trim($my_folder,'/');
$url = trim(get_bloginfo('url'),'/');
if ( !preg_match( '~nofollow~is',$matches[0][$i])
&& (preg_match('~' . $my_folder . '/?$~', $matches[0][$i])
|| !preg_match( '~'. $url .'/?$~',$matches[0][$i])))
This is a shot in the dark, but try:
preg_match( '/' . preg_quote( get_bloginfo('url'), '/' ) . '?/', $matches[0][$i] )
You can use whatever char you want in place of the / chars. I'm guessing that you're using wordpress and guessing that get_bloginfo('url') is normalized to always have a trailing slash. If that is the case, the last slash will be selected optionally by the ? at the end of the regex.
You should just use strstr() or strpos() if it's fixed strings anyway.
Your example rewritten:
if (!strstr($matches[0][$i], "nofollow")
and strstr($matches[0][$i], $my_folder)
or !strstr($matches[0][$i], $url) )
strpos works similarly, but you need an extra boolean check:
if (strpos($matches, "nofollow") === FALSE
or strpos($matches, $my_folder) !== FALSE)
I have some links in a Powerpoint presentation, and for some reason, when those links get clicked, it adds a return parameter to the URL. Well, that return parameter is causing my Joomla site's MVC pattern to get bungled.
What's an efficient way to strip off this return parameter using PHP?
Example:
http://mydomain.example/index.php?id=115&Itemid=283&return=aHR0cDovL2NvbW11bml0
The safest "correct" method would be:
Parse the url into an array with parse_url()
Extract the query portion, decompose that into an array using parse_str()
Delete the query parameters you want by unset() them from the array
Rebuild the original url using http_build_query()
Quick and dirty is to use a string search/replace and/or regex to kill off the value.
In a different thread Justin suggests that the fastest way is to use strtok()
$url = strtok($url, '?');
See his full answer with speed tests as well here: https://stackoverflow.com/a/1251650/452515
This is to complement Marc B's answer with an example, while it may look quite long, it's a safe way to remove a parameter. In this example we remove page_number
<?php
$x = 'http://url.example/search/?location=london&page_number=1';
$parsed = parse_url($x);
$query = $parsed['query'];
parse_str($query, $params);
unset($params['page_number']);
$string = http_build_query($params);
var_dump($string);
function removeParam($url, $param) {
$url = preg_replace('/(&|\?)'.preg_quote($param).'=[^&]*$/', '', $url);
$url = preg_replace('/(&|\?)'.preg_quote($param).'=[^&]*&/', '$1', $url);
return $url;
}
parse_str($queryString, $vars);
unset($vars['return']);
$queryString = http_build_query($vars);
parse_str parses a query string, http_build_query creates a query string.
Procedural Implementation of Marc B's Answer after refining Sergey Telshevsky's Answer.
function strip_param_from_url($url, $param)
{
$base_url = strtok($url, '?'); // Get the base URL
$parsed_url = parse_url($url); // Parse it
// Add missing {
if(array_key_exists('query',$parsed_url)) { // Only execute if there are parameters
$query = $parsed_url['query']; // Get the query string
parse_str($query, $parameters); // Convert Parameters into array
unset($parameters[$param]); // Delete the one you want
$new_query = http_build_query($parameters); // Rebuilt query string
$url =$base_url.'?'.$new_query; // Finally URL is ready
}
return $url;
}
// Usage
echo strip_param_from_url( 'http://url.example/search/?location=london&page_number=1', 'location' )
You could do a preg_replace like:
$new_url = preg_replace('/&?return=[^&]*/', '', $old_url);
Here is the actual code for what's described above as the "the safest 'correct' method"...
function reduce_query($uri = '') {
$kill_params = array('gclid');
$uri_array = parse_url($uri);
if (isset($uri_array['query'])) {
// Do the chopping.
$params = array();
foreach (explode('&', $uri_array['query']) as $param) {
$item = explode('=', $param);
if (!in_array($item[0], $kill_params)) {
$params[$item[0]] = isset($item[1]) ? $item[1] : '';
}
}
// Sort the parameter array to maximize cache hits.
ksort($params);
// Build new URL (no hosts, domains, or fragments involved).
$new_uri = '';
if ($uri_array['path']) {
$new_uri = $uri_array['path'];
}
if (count($params) > 0) {
// Wish there was a more elegant option.
$new_uri .= '?' . urldecode(http_build_query($params));
}
return $new_uri;
}
return $uri;
}
$_SERVER['REQUEST_URI'] = reduce_query($_SERVER['REQUEST_URI']);
However, since this will likely exist prior to the bootstrap of your application, you should probably put it into an anonymous function. Like this...
call_user_func(function($uri) {
$kill_params = array('gclid');
$uri_array = parse_url($uri);
if (isset($uri_array['query'])) {
// Do the chopping.
$params = array();
foreach (explode('&', $uri_array['query']) as $param) {
$item = explode('=', $param);
if (!in_array($item[0], $kill_params)) {
$params[$item[0]] = isset($item[1]) ? $item[1] : '';
}
}
// Sort the parameter array to maximize cache hits.
ksort($params);
// Build new URL (no hosts, domains, or fragments involved).
$new_uri = '';
if ($uri_array['path']) {
$new_uri = $uri_array['path'];
}
if (count($params) > 0) {
// Wish there was a more elegant option.
$new_uri .= '?' . urldecode(http_build_query($params));
}
// Update server variable.
$_SERVER['REQUEST_URI'] = $new_uri;
}
}, $_SERVER['REQUEST_URI']);
NOTE: Updated with urldecode() to avoid double encoding via http_build_query() function.
NOTE: Updated with ksort() to allow params with no value without an error.
This one of many ways, not tested, but should work.
$link = 'http://mydomain.example/index.php?id=115&Itemid=283&return=aHR0cDovL2NvbW11bml0';
$linkParts = explode('&return=', $link);
$link = $linkParts[0];
Wow, there are a lot of examples here. I am providing one that does some error handling. It rebuilds and returns the entire URL with the query-string-param-to-be-removed, removed. It also provides a bonus function that builds the current URL on the fly. Tested, works!
Credit to Mark B for the steps. This is a complete solution to tpow's "strip off this return parameter" original question -- might be handy for beginners, trying to avoid PHP gotchas. :-)
<?php
function currenturl_without_queryparam( $queryparamkey ) {
$current_url = current_url();
$parsed_url = parse_url( $current_url );
if( array_key_exists( 'query', $parsed_url )) {
$query_portion = $parsed_url['query'];
} else {
return $current_url;
}
parse_str( $query_portion, $query_array );
if( array_key_exists( $queryparamkey , $query_array ) ) {
unset( $query_array[$queryparamkey] );
$q = ( count( $query_array ) === 0 ) ? '' : '?';
return $parsed_url['scheme'] . '://' . $parsed_url['host'] . $parsed_url['path'] . $q . http_build_query( $query_array );
} else {
return $current_url;
}
}
function current_url() {
$current_url = 'http' . (isset($_SERVER['HTTPS']) ? 's' : '') . '://' . "{$_SERVER['HTTP_HOST']}{$_SERVER['REQUEST_URI']}";
return $current_url;
}
echo currenturl_without_queryparam( 'key' );
?>
$var = preg_replace( "/return=[^&]+/", "", $var );
$var = preg_replace( "/&{2,}/", "&", $var );
Second line will just replace && to &
very simple
$link = "http://example.com/index.php?id=115&Itemid=283&return=aHR0cDovL2NvbW11bml0"
echo substr($link, 0, strpos($link, "return") - 1);
//output : http://example.com/index.php?id=115&Itemid=283
#MarcB mentioned that it is dirty to use regex to remove an url parameter. And yes it is, because it's not as easy as it looks:
$urls = array(
'example.com/?foo=bar',
'example.com/?bar=foo&foo=bar',
'example.com/?foo=bar&bar=foo',
);
echo 'Original' . PHP_EOL;
foreach ($urls as $url) {
echo $url . PHP_EOL;
}
echo PHP_EOL . '#AaronHathaway' . PHP_EOL;
foreach ($urls as $url) {
echo preg_replace('#&?foo=[^&]*#', null, $url) . PHP_EOL;
}
echo PHP_EOL . '#SergeS' . PHP_EOL;
foreach ($urls as $url) {
echo preg_replace( "/&{2,}/", "&", preg_replace( "/foo=[^&]+/", "", $url)) . PHP_EOL;
}
echo PHP_EOL . '#Justin' . PHP_EOL;
foreach ($urls as $url) {
echo preg_replace('/([?&])foo=[^&]+(&|$)/', '$1', $url) . PHP_EOL;
}
echo PHP_EOL . '#kraftb' . PHP_EOL;
foreach ($urls as $url) {
echo preg_replace('/(&|\?)foo=[^&]*&/', '$1', preg_replace('/(&|\?)foo=[^&]*$/', '', $url)) . PHP_EOL;
}
echo PHP_EOL . 'My version' . PHP_EOL;
foreach ($urls as $url) {
echo str_replace('/&', '/?', preg_replace('#[&?]foo=[^&]*#', null, $url)) . PHP_EOL;
}
returns:
Original
example.com/?foo=bar
example.com/?bar=foo&foo=bar
example.com/?foo=bar&bar=foo
#AaronHathaway
example.com/?
example.com/?bar=foo
example.com/?&bar=foo
#SergeS
example.com/?
example.com/?bar=foo&
example.com/?&bar=foo
#Justin
example.com/?
example.com/?bar=foo&
example.com/?bar=foo
#kraftb
example.com/
example.com/?bar=foo
example.com/?bar=foo
My version
example.com/
example.com/?bar=foo
example.com/?bar=foo
As you can see only #kraftb posted a correct answer using regex and my version is a little bit smaller.
Remove Get Parameters From Current Page
<?php
$url_dir=$_SERVER['REQUEST_URI'];
$url_dir_no_get_param= explode("?",$url_dir)[0];
echo $_SERVER['HTTP_HOST'].$url_dir_no_get_param;
This should do it:
public function removeQueryParam(string $url, string $param): string
{
$parsedUrl = parse_url($url);
if (isset($parsedUrl[$param])) {
$baseUrl = strtok($url, '?');
parse_str(parse_url($url)['query'], $query);
unset($query[$param]);
return sprintf('%s?%s',
$baseUrl,
http_build_query($query)
);
}
return $url;
}
Simple solution that will work for every url
With this solution $url format or parameter position doesn't matter, as an example I added another parameter and anchor at the end of $url:
https://example.com/index.php?id=115&Itemid=283&return=aHR0cDovL2NvbW11bml0&bonus=test#test2
Here is the simple solution:
$url = 'https://example.com/index.php?id=115&Itemid=283&return=aHR0cDovL2NvbW11bml0&bonus=test#test2';
$url_query_stirng = parse_url($url, PHP_URL_QUERY);
parse_str( $url_query_stirng, $url_parsed_query );
unset($url_parsed_query['return']);
$url = str_replace( $url_query_stirng, http_build_query( $url_parsed_query ), $url );
echo $url;
Final result for $url string is:
https://example.com/index.php?id=115&Itemid=283&bonus=test#test2
Some of the examples posted are so extensive. This is what I use on my projects.
function removeQueryParameter($url, $param){
list($baseUrl, $urlQuery) = explode('?', $url, 2);
parse_str($urlQuery, $urlQueryArr);
unset($urlQueryArr[$param]);
if(count($urlQueryArr))
return $baseUrl.'?'.http_build_query($urlQueryArr);
else
return $baseUrl;
}
function remove_attribute($url,$attribute)
{
$url=explode('?',$url);
$new_parameters=false;
if(isset($url[1]))
{
$params=explode('&',$url[1]);
$new_parameters=ra($params,$attribute);
}
$construct_parameters=($new_parameters && $new_parameters!='' ) ? ('?'.$new_parameters):'';
return $new_url=$url[0].$construct_parameters;
}
function ra($params,$attr)
{ $attr=$attr.'=';
$new_params=array();
for($i=0;$i<count($params);$i++)
{
$pos=strpos($params[$i],$attr);
if($pos===false)
$new_params[]=$params[$i];
}
if(count($new_params)>0)
return implode('&',$new_params);
else
return false;
}
//just copy the above code and just call this function like this to get new url without particular parameter
echo remove_attribute($url,'delete_params'); // gives new url without that parameter
I know this is an old question but if you only want to remove one or few named url parameter you can use this function:
function RemoveGet_Regex($variable, $rewritten_url): string {
$rewritten_url = preg_replace("/(\?)$/", "", preg_replace("/\?&/", "?", preg_replace("/((?<=\?)|&){$variable}=[\w]*/i", "", $rewritten_url)));
return $rewritten_url;
}
function RemoveGet($name): void {
$rewritten_url = "https://$_SERVER[HTTP_HOST]$_SERVER[REQUEST_URI]";
if(is_array($name)) {
for($i = 0; $i < count($name); $i++) {
$rewritten_url = RemoveGet_Regex($name[$i], $rewritten_url);
$is_set[] = isset($_GET[$name[$i]]);
}
$array_filtered = array_filter($is_set);
if (!empty($array_filtered)) {
header("Location: ".$rewritten_url);
}
}
else {
$rewritten_url = RemoveGet_Regex($name, $rewritten_url);
if(isset($_GET[$name])) {
header("Location: ".$rewritten_url);
}
}
}
In the first function preg_replace("/((?<=\?)|&){$variable}=[\w]*/i", "", $rewritten_url) will remove the get parameter, and the others will tidy it up. The second function will then redirect.
RemoveGet("id"); will remove the id=whatever from the url. The function can also work with arrays. For your example,
Remove(array("id","Item","return"));
To strip any parameter from the url using PHP script you need to follow this script:
function getNewArray($array,$k){
$dataArray = $array;
unset($array[$k]);
$dataArray = $array;
return $dataArray;
}
function getFullURL(){
return (isset($_SERVER['HTTPS']) && $_SERVER['HTTPS'] === 'on' ? "https" : "http") . "://$_SERVER[HTTP_HOST]$_SERVER[REQUEST_URI]";
}
$url = getFullURL();
$url_components = parse_url($url);
// Use parse_str() function to parse the
// string passed via URL
parse_str($url_components['query'], $params);
print_r($params);
<ul>
<?php foreach($params as $k=>$v){?>
<?php
$newArray = getNewArray($params,$k);
$parameters = http_build_query($newArray);
$newURL = $_SERVER['PHP_SELF']."?".$parameters;
?>
<li><?=$v;?> X
<?php }?>
</ul>
here is functions optimized for speed. But this functions DO NOT remove arrays like a[]=x&a[1]bb=y&a[2]=z by array name.
function removeQueryParam($query, $param)
{
$quoted_param = preg_quote($param, '/');
$pattern = "/(^$quoted_param=[^&]*&?)|(&$quoted_param=[^&]*)/";
return preg_replace($pattern, '', $query);
}
function removeQueryParams($query, array $params)
{
if ($params)
{
$pattern = '/';
foreach ($params as $param)
{
$quoted_param = preg_quote($param, '/');
$pattern .= "(^$quoted_param=[^&]*&?)|(&$quoted_param=[^&]*)|";
}
$pattern[-1] = '/';
return preg_replace($pattern, '', $query);
}
return $query;
}
<? if(isset($_GET['i'])){unset($_GET['i']); header('location:/');} ?>
This will remove the 'i' parameter from the URL. Change the 'i's to whatever you need.
I'm building a little Twitter thing in PHP and I'm trying to parse URLs, #replies and #hashtags and make them into clickable links.
The #replies would link to http://twitter.com/replies
Hashtags would like to http://search.twitter.com/search?q=%23hashtags
I've found a class for parsing URLs and I'm wondering if this could also be used to parse #replies and #hashtags as well:
// http://josephscott.org/archives/2008/11/makeitlink-detecting-urls-in-text-and-making-them-links/
class MakeItLink {
protected function _link_www( $matches ) {
$url = $matches[2];
$url = MakeItLink::cleanURL( $url );
if( empty( $url ) ) {
return $matches[0];
}
return "{$matches[1]}<a href='{$url}'>{$url}</a>";
}
public function cleanURL( $url ) {
if( $url == '' ) {
return $url;
}
$url = preg_replace( "|[^a-z0-9-~+_.?#=!&;,/:%#$*'()x80-xff]|i", '', $url );
$url = str_replace( array( "%0d", "%0a" ), '', $url );
$url = str_replace( ";//", "://", $url );
/* If the URL doesn't appear to contain a scheme, we
* presume it needs http:// appended (unless a relative
* link starting with / or a php file).
*/
if(
strpos( $url, ":" ) === false
&& substr( $url, 0, 1 ) != "/"
&& !preg_match( "|^[a-z0-9-]+?.php|i", $url )
) {
$url = "http://{$url}";
}
// Replace ampersans and single quotes
$url = preg_replace( "|&([^#])(?![a-z]{2,8};)|", "&$1", $url );
$url = str_replace( "'", "'", $url );
return $url;
}
public function transform( $text ) {
$text = " {$text}";
$text = preg_replace_callback(
'#(?<=[\s>])(\()?([\w]+?://(?:[\w\\x80-\\xff\#$%&~/\-=?#\[\](+]|[.,;:](?![\s<])|(?(1)\)(?![\s<])|\)))*)#is',
array( 'MakeItLink', '_link_www' ),
$text
);
$text = preg_replace( '#(<a( [^>]+?>|>))<a [^>]+?>([^>]+?)</a></a>#i', "$1$3</a>", $text );
$text = trim( $text );
return $text;
}
}
I think what you're looking to do is essentially what I've included below. You'd add these two statements in transform method, just before the return statement.
$text = preg_replace('##(\w+)#', '$0', $text);
$text = preg_replace('/#(\w+)/', '$0', $text);
Is that what you're looking for?
Twitter recently released to open source both java and ruby (gem) implementations of the code they use for finding user names, hash tags, lists and urls.
It is very regular expression oriented.