Detecting emails in a text - php

Question

I'm trying to create a function that translates every occurrence of a plain text email address in a given string into it's htmlized version.
Let's say I have the following code, where htmlizeEmails is the function I'm looking for:
$str = "Send me an email to bob#example.com.";
echo htmlizeEmails($str); // Echoes "Send me an email to bob#example.com."
If possible, I'd like this function to use the filter_var function to check if the email is valid.
Does anyone know how to do this? Thanks!
Edit:
Thanks for the answers, I used Shocker's regex to match potential email addresses and then, only if the filter_var validates it, it gets replaced.
function htmlizeEmails($text)
preg_match_all('/([a-zA-Z0-9._%+-]+#[a-zA-Z0-9.-]+\.[a-zA-Z]{2,6})/', $text, $potentialEmails, PREG_SET_ORDER);
$potentialEmailsCount = count($potentialEmails);
for ($i = 0; $i < $potentialEmailsCount; $i++) {
if (filter_var($potentialEmails[$i][0], FILTER_VALIDATE_EMAIL)) {
$text = str_replace($potentialEmails[$i][0], '' . $potentialEmails[$i][0] .'', $text);
}
}
}

Answer 1

$str = preg_replace('/([a-zA-Z0-9._%+-]+#[a-zA-Z0-9.-]+\.[a-zA-Z]{2,6})/', '$1', $str);
where ([a-zA-Z0-9._%+-]+#[a-zA-Z0-9.-]+\.[a-zA-Z]{2,6}) is the regular expression used for detecting an email address (this is a general example, email addresses may be more complicated than this and not all addresses may be covered, but finding the perfect regex for emails is up to you)

Answer 2

There's always matching every sequence of non-space characters and testing those with filter_var, but this is probably one of those cases where it's just better to use regular expressions.
echo preg_replace('/(([\w!#$%&\'*+\-\/=?^`{|}~]|\\\\\\\\|\\\\?"|\\\\ )+\.)*([\w!#$%&\'*+\-\/=?^`{|}~]|\\\\\\\\|\\\\?"|\\\\ )+#((\w+[\.-])*[a-zA-Z]{2,}|\[(\d{1,3}\.){3}\d{1,3}\])/', '$0', $str);
I've tried to follow the standard as best I could without making it ridiculously compliant. And anybody who puts comments in his or her e-mail address can just be forgotten safely, I think. And it definitely works for common e-mails.
EDIT: After a long, difficult struggle, here's my regular expression to match everything:
((([a-zA-Z0-9!\#\$%&'*+\-\/=?^_`{|}~]+|"([a-zA-Z0-9!\#\$%&'*+\-\/=?^_`{|}~(),:;<>#\[\]]|\\[ \\"])+")\.)*([a-zA-Z0-9!\#\$%&'*+\-\/=?^_`{|}~]+|"([a-zA-Z0-9!\#\$%&'*+\-\/=?^_`{|}~(),:;<>#\[\]]|\\[ \\"])+"))#((([a-zA-Z0-9]([a-zA-Z0-9]*(\-[a-zA-Z0-9]*)*)?\.)*[a-zA-Z]{2,}|\[((0?\d{1,2}|1\d{2}|2[0-4]\d|25[0-5])\.){3}(0?\d{1,2}|1\d{2}|2[0-4]\d|25[0-5])\]|\[[Ii][Pp][vV]6(:[0-9a-fA-F]{0,4}){6}\]))
Enjoy escaping it!

Answer 3

The code below should work fine, but it regex is easier to go with.
$str = "Send me an email to bob#example.com.";
function htmlizestring($a){
if(substr_count($a,"#") != 1){
return false;
}else{
$b4 = stristr($a,"#",true);
$b4pos = strripos($b4," ")+1;
$b4 = trim(substr($b4,$b4pos));
$after = stristr($a,"#");
if(substr_count($after, " ") == 0){
$after=rtrim($after," .,");
}else{
$after=trim(stristr($after," ",true));
}
$email = $b4.$after;
echo $email;
if(filter_var($email, FILTER_VALIDATE_EMAIL)){
echo "Send me an email at: <a href='mailto:".$email."'>".$email."</a>";
}else{
return false;
}
}
}
htmlizestring($str);
I happen to use stristr() with the third parameter TRUE, which only works on php 5.3+

Answer 4

filter_var is nice to validate an email, but Dominic Sayers' is_email is even better, and my personal choice.
source code: http://code.google.com/p/isemail/source/browse/PHP/trunk/is_email.php
about: http://isemail.info/about