What is the main issue the user is facing with PHP in converting CoPro format to HTML?

The main issue the user is facing is that they need to convert CoPro format to HTML using PHP. To do this, they can use regular expressions to match and replace the CoPro format with HTML tags. By defining the CoPro format patterns and their corresponding HTML tags, they can easily convert the text.

<?php
// Define CoPro format patterns and their corresponding HTML tags
$patterns = array(
    '/\[b\](.*?)\[\/b\]/' => '<strong>$1</strong>', // bold
    '/\[i\](.*?)\[\/i\]/' => '<em>$1</em>', // italic
    '/\[u\](.*?)\[\/u\]/' => '<u>$1</u>', // underline
);

// Sample CoPro format text
$coproText = "[b]This[/b] is [i]some[/i] [u]text[/u] in CoPro format.";

// Convert CoPro format to HTML
$htmlText = preg_replace(array_keys($patterns), array_values($patterns), $coproText);

echo $htmlText;
?>