How to detect usernames in a comment using preg_match? - php

Question

I am trying to design a comment/reply system like the one in stackoverflow where if #username is mentioned in a comment then a notification is send to him.
As an example take the comment
$comment="hello #myname and #my-name and #my+name and #my%name and #my&name and #my_name and #my name #my/name and #3535 and #12";
the problem is my code
if(preg_match('~#([^\s]+)~', $comment, $matches)){
print_r($matches);
}
only finds the username #myname. Is there a way to fix this so that it detects all usernames?
Also, which of the usernames mentioned in the comment above are valid usernames in stackoverflow for example are my-name, my%name valid usernames and are they detected when they are mensioned in a stackoverflow comment.
Finally, is it possible to replace every valid username in my comment example by <strong>username</strong>?

Answer 1

The problem with your code is that the preg_match() function finds the first matched pattern and returns true or false without moving ahead along the rest of the string. So it won't go through the next usernames.
For this wrapping the preg_match() conditional in a loop can be a good deal.
This code should get it done!
$comment="hello #myname and #my-name and #my+name and #my%name and #my&name and #my_name and #my name #my/name and #3535 and #12";
$comment_arr = explode(' ', $comment);
// echo '<pre>';
// print_r($comment_arr);
// echo '</pre>';
$usernames = [];
$new_comment_arr = [];
for ($i=0; $i < count($comment_arr) ; $i++)
{
if( preg_match('/^#(.*)/', $comment_arr[$i]) )
{
array_push($usernames, $comment_arr[$i]); // push the usernames
array_push($new_comment_arr, '<strong>'.$comment_arr[$i].'</strong>'); // push the usernames with '<strong>' wrapped around in the new comments array
}
else
array_push($new_comment_arr, $comment_arr[$i]); // push the unmatched words(other words) in the new comments array
}
echo '<pre>';
print_r($new_comment_arr);
print_r($usernames);
echo '</pre>';
$new_comment = implode(' ', $new_comment_arr); // implode the new array
echo $new_comment; // the new comment with '<strong>' wrapped around the usernames
The username #my name shouldn't be allowed.
In some cases if you want the username to be in URL then such a username gets converted to #my%20name.
Also do not allow '/' in a username as, if you Rewrite the URL, it will be treated as an argument and can lead to 404 Errors.
As far as I'm concerned, you should allow only letters, numbers and underscores( '_' ) in a username.

Answer 2

Why not try Social Plugin for comments
I suggest you to use Facebook plugin for comments
for more details http://developers.facebook.com/docs/plugins/comments

Answer 3

I think you must collect all the name that started sit char # in array so you can use the array for everything you want like send notification to all of them by loop the array.
I have made a code to accommodate it.
<?php
$comment="hello #myname and #my-name and #my+name and #my%name and #my&name and #my_name and #my name #my/name and #3535 and #12";
$keywords = preg_split("/[\s]+/", $comment);
foreach($keywords as $row=>$value){
if(preg_match("/^#/",$value)==0){
unset($keywords[$row]);
}
}
print_r($keywords);
?>