Question

I’m working on a program where I need to match a regular expression and a string. The string is pretty simple actually but I’m having problems with my current regex (I’m using the .net regex engine)

My current regular expression is “^[VvEeTtPp][^a-zA-Z0-9\s]\d{0,12}?$”

Now, the string I want to match always follows this pattern

1. First a single letter (only letters allowed are V, E, P, T in either case)
2. Then, a dash
3. Finally from 4 to 12 digits.

There is a final restriction that is that the regex must match any substring that complies the rules (for example “V” or “E-” or “P-123”)

The regex works fairly well, but it will accept things like “V–“.

Could someone help me write a better expression??

Thanks

Answer 1

Well, a substring of the 4-12 rule really just makes it a 1-12 rule, so how about:

        Regex re = new Regex(@"^[VvEeTtPp](-|-[0-9]{1,12})?$");
        Console.WriteLine(re.IsMatch("B"));
        Console.WriteLine(re.IsMatch("V"));
        Console.WriteLine(re.IsMatch("E-"));
        Console.WriteLine(re.IsMatch("P-123"));
        Console.WriteLine(re.IsMatch("V--"));