Question

How to write regular expression that matches only numbers,text and only these two special characters # and –
[a-zA-Z0-9#-\s]+ anything else should be rejected

Answer 1

You could a regular expression similar to this

^(\d|[a-z]|[A-Z]|#|-)*$

Below the code I used for checking the regular expression in c#:

string input = @"343243-2df---ds#SFD#FD";
string pattern = @"^(\d|[a-z]|[A-Z]|#|-)*$";

Console.WriteLine(Regex.Match(input, pattern).Success);
Console.ReadLine();

Also, for future reference material, you could see this regular expression site: http://www.regular-expressions.info/