Question

I have a string and I want to make sure it only contains characters in BSEO|0123456789. I tried to do that with this regex

Regex r = new Regex("^[BSEO|0123456789]");
if (r.IsMatch(str)) throw new Exception("Invalid character.");

but it doesn’t behave correctly, (e.g. string SE throws exception). What am I doing wrong, how can I fix it, and is there a better solution to this than using regex?

Answer 1

You can use linq:

if (str.Distinct().Except("BSEO|0123456789").Any())
    throw new Exception("Invalid character."); 

EDIT

After pondering this for a while, I think the call to Distinct() may be a failed attempt at micro-optimization. If performance is important, try with and without. It may well perform better without.

EDIT 2

I am now convinced that Distinct() makes the query run more slowly. Use this instead:

if (str.Except("BSEO|0123456789").Any())
    throw new Exception("Invalid character.");