Ereg expert needed

i have a slight problem i am making a forum and want the user not to be able to input html code. they can make an image by typing

they can make by just typing:

i use the code:

$text = eregi_replace("((http|mailto|ftp):\/\/[^{[:space:]<>]{1,})",} "<a href=\"\1\">\1</a>",$text);

i want to know how to check to see if there is an [img] tag before the url so that the image doesn't get all screwed up?

You can use:

(\[img\])?

to test for an optional "[img]" tag.