compare strings problem

[adunphy]

if (ereg("[[url]http://[/url]]",$url))
{
print "Error: Your website may not contain [url]http://[/url]";
}

what's wrong with that? I want it to flag if the user puts in [url]http://[/url] in their website

TIA

[uidzer0]

you need to escape the special characters