Regular Expressions: low-caps, dots, zero spaces

Question

how do I write an expression which checks for lowcaps, dots, and without any white space in the string?

the code below so far was trying to check for lowcaps and dots (i

Answer 1

I think you want this:

if ( preg_match( '/[^a-z0-9.]/' ) ) {
    $error = true;
}

Keep in mind, I removed the !. Now if this matches, you get the error. VolkerK reversed it but forgot to remove the !, I think.

Also, http://regexpal.com/ is your friend.