Help w/ regular expressions for banned words

$num=count($bannedwords); for($i=0;$i<$num-1;$i++) { $string = eregi_replace("\b$bannedwords[$i]\b","[censored]",$string); } For whatever reason, no word in $bannedwords will match in the string. I've tested it with simple expressions like "\btest\b" and it will not match the word "test". Does it have something to do with the 2 "\b"s found in the code? After removing them, it replaces all instances of $bannedwords, even in the middle of words, which is not good. Any suggestions? TIA, Neal