How to remove html special chars?

Either decode them using html_entity_decode or remove them using preg_replace:

$Content = preg_replace("/&#?[a-z0-9]+;/i","",$Content); 

(From here)

EDIT: Alternative according to Jacco's comment

might be nice to replace the '+' with {2,8} or something. This will limit the chance of replacing entire sentences when an unencoded '&' is present.

$Content = preg_replace("/&#?[a-z0-9]{2,8};/i","",$Content); 

Use html_entity_decode to convert HTML entities.

You'll need to set charset to make it work correctly.

In addition to the good answers above, PHP also has a built-in filter function that is quite useful: filter-var.

To remove HMTL characters, use:

$cleanString = filter_var($dirtyString, FILTER_SANITIZE_STRING);

More info:

1. function.filter-var
2. filter_sanitize_string

You may want take a look at htmlentities() and html_entity_decode() here

$orig = "I'll \"walk\" the <b>dog</b> now";

$a = htmlentities($orig);

$b = html_entity_decode($a);

echo $a; // I'll &quot;walk&quot; the &lt;b&gt;dog&lt;/b&gt; now

echo $b; // I'll "walk" the <b>dog</b> now