Regular Expression that Matches Any Number or Letter or Dash

Question

Given searchString = "23423asdfa-''"

This regular expression should evaluate to false but it does not! Any ideas?

Regex rgx = new Regex(@"[\w-]*");
rgx.IsMatch(searchString)

Answer 1

It's because you haven't constrained it to match the entire string. Hence it is allowed to consider matches on subsets of the string. A very large subset of the string matches the data hence the regex returns true.

Try the following to force it to match the entire input.

Regex rgx = new Regex(@"^[\w-]*$");
rgx.IsMatch(searchString)

Answer 2

You need to anchor your expression. If you don't, then if any substring of the input matches, the regex match is considered successful. Change the regex to "^[\w-]*$" where the ^ and $ will match the beginning and end of the string, respectively.