Regex to remove all (non numeric OR period)

Question

I need for text like \"joe ($3,004.50)\" to be filtered down to 3004.50 but am terrible at regex and can\'t find a suitable solution. So only numbers and periods should stay -

Answer 1

For the accepted answer, MatthewGunn raises a valid point in that all digits, commas, and periods in the entire string will be condensed together. This will avoid that:

string s = "joe.smith ($3,004.50)";
Regex r = new Regex(@"(?:^|[^w.,])(\d[\d,.]+)(?=\W|$)/)");
Match m = r.match(s);
string v = null;
if (m.Success) {
  v = m.Groups[1].Value;
  v = Regex.Replace(v, ",", "");
}