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Online Sandbox for SQL and PHP: Write, Run, Test, and Share SQL Queries and PHP Code
<?php
$string = "<h1>Hello, <b>World!</b></h1> <p>This is a <a href='#'>link</a>. <img src='image.jpg' /></p>";
$whitelist = ['b', 'a', 'p', 'img'];
preg_match_all('/<([a-zA-Z0-9]+)(\s[^>]*)?>/i', $string, $matches);
array_walk($matches[1], function($tag) use ($whitelist) {
if (!in_array(strtolower($tag), $whitelist)) {
die($tag . ' is not allowed!!');
}
});