How to detect exact length in regex

Question

I have two regular expressions that validate the values entered.

One that allows any length of Alpha-Numeric value:

@"^\s*(?<ALPHA>[A-Z0-9]+)\s*"

And the other only allows numerical values:

@"^\s*(?<NUM>[0-9]{10})"

How can I get a numerical string of the length of 11 not to be catched by the NUM regex.

Answer 1

I think what you're trying to say is that you don't want to allow any more than 10 digits. So, just add a $ at the end to specify the end of the regex.

Example: @"^\s*(?[0-9]{10})$"

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Here's my original answer, but I think I read you too exact.

string myRegexString = `@"(?!(^\d{11}$)` ... your regex here ... )";

That reads "while ahead is not, start, 11 digits, end"