Simple integer regular expression

Question

I have ValidationRegularExpression=\"[0-9]\" which only allows a single character. How do I make it allow between (and including) 1 and 7 digits? I tried [0-9

Answer 1

If you want to avoid leading zeros, you can use this:

^(?!0\d)\d{1,7}$

The first part is a negative lookahead assertion, that checks if there is a 0 followed by a number in the string. If so no match.

Check online here: http://regexr.com?2thtr