String validation in .NET

Question

String validation ..

I want to validate a string contains only the following characters :

• A-Z
• 0-9
• "/"
• "-"

What's the best way to achieve this. I have tried to use a REGEXP but this is returning valid if any of the characters are valid, not if all of the characters are valid.

Answer 1

Try:

@"^[A-Z0-9/-]*$"

Or if you need to limit the number of characters:

@"^[A-Z0-9/-]{lowerbound,upperbound}$"

Edit: Added start and end anchors

Answer 2

You could negate using [^A-Z0-9/-]. If it matches you know there are invalid characters.

if (Regex.IsMatch("input",@"[^A-Z0-9/-]"))
{
   //invalid character found
}

The character ^ inside the bracket negates the set, meaning "find anything thats not here".