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John Fowler wrote:

> In the following regex, what does the '/' in [^/] mean and what does the  '?/' at the end of the string mean?
> 
> Regex r = new Regex(@"^(?<proto>\w+)://[^/]+?(?<port>:\d+)?/" etc.


  [^/]+?		At least 1 character besides '/'. 
			As few non-/ as possible.

  (?<port>:\d+)?/	Optionally, a colon followed by a number. 
			Then a mandatory '/'.
 
> Similarly, this Regular Expression is used to replace invalid characters, EXCEPT "." and "@" and "-" but my reading of it is that it replaces (beginning from the left side, as specified by the "^" ) all word-length characters ( the "\w" ) and the "\", ".", "@" and "-" characters as well.
> 
> // Replace invalid characters with empty strings.
>         return Regex.Replace(strIn, @"[^\w\.@-]", "");
> 
> What am I missing?

You're not. This matches anything except alpha-numeric chars, '.',
'@', and '-'. (Try it in
<http://www.midnightbeach.com/dotnet/regexExplorer.html> or any other
regex workbench.)

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