"<" and ">" impact

[markjia]

I need to display strings stored in mySQL tables, but the problem I'm having is with converting special characters into valid HTML. The thing is that the strings also store html tags (like "bold", "italic", etc), so I don't know how to convert "<" and ">" into "&lt;" and "&gt;" without also destroying the tags like "&lt;h1&gt;".

[markjia]

I forgot to mention the other part of the question...
What is the impact of leaving "<" and ">" untouched? will it display properly on all browsers?

[Anon]

I would suggest you to use htmlentities(), then to use eregi_replace()...

Ex :
$string = htmlentities($string);
$string = eregi_replace("&lt;h1&gt;", "<h1>", $string);
$string = eregi_replace("&lt;h2&gt;", "<h2>", $string);

You could make an array to simplify the job...

$tags = array("h1", "h2", "h3", "h4", "h5", "h6", "b", "i", "u", .........);
$string = htmlentities($string);
for($i = 0; $i < count($tags); $i++) {
eregi_replace("&lt;" . $tags[$i] . "&gt;", "<" . $tags[$i] . ">", $string);
}