Match a regular expression against any non-character or number

Answer 1

You can use \b, see Whole word bounderies.

Answer 2

Look up \b (word boundary):

Matches at the position between a word character (anything matched by \w) and a non-word character (anything matched by [^\w] or \W) as well as at the start and/or end of the string if the first and/or last characters in the string are word characters.

(http://www.regular-expressions.info/reference.html)

So: \brob\b matches rob, but not problem.