Php title regular expression - php

Question

I'm trying to replace a title tag from |title|Page title| to <title>Page Title</title>, using this regular expression. But being a complete amateur, it's not gone to well..
'^|title|^[a-zA-Z0-9_]{1,}|$' => '<title>$1</title>'
I would love to know how to fix it, and more importantly, what I did wrong and why it was wrong.

Answer 1

You almost got it:
You should escape the | characters as they have special meaning in a
regex and you are using it as a plain character.
You should add the space character to your search group
$string = '|title|Page title|';
$pattern = '/\|title\|([a-zA-Z0-9_ ]{1,})\|/';
$replacement = '<title>$1</title>';
echo preg_replace($pattern, $replacement, $string); //echoes <title>Page title</title>
See working demo
OP posted some code in comments which is wrong, try this version:
$regular_expressions = array( array( '/\|title\|([a-zA-Z0-9_ ]{1,})\|/' , '<title>$1</title>' ));
foreach($regular_expressions as $regexp){
$data = preg_replace($regexp[0], $regexp[1], $data);
}

Answer 2

Heres a little function I came up with a while back to essentially scrape the titles of a page when users submitted links through my service. What this function does is will get the contents of a provided URL. Seek a title tag, if found, get whats between the title tag and dump it's result. With a little tweaking I am sure you can use a replace method for whatever your doing, and make it work for your needs. So this is more of a starting point rather than an answer but overall I hope it helps to some extent.
$url = 'http://www.chrishacia.com';
function get_page_title($url){
if( !($data = file_get_contents($url)) ) return false;
if( preg_match("#<title>(.+)<\/title>#iU", $data, $t)) {
return trim($t[1]);
} else {
return false;
}
}
var_dump(get_page_title($url));

Answer 3

<?php
$s = "|title|Page title|";
$s = preg_replace('/^\|title\|([^\|]+)\|/', "<title>$1</title>", $s);
echo $s;
?>