Regular expressions, maximum string length

Question

Regular Expressions

There is a regular expression: "(\d+\.)+", which describes strings like 111.223.123.12.
How can I add a check that the total length of the string, say, does not exceed twenty characters.

Thank you.

Answer 1

Is there any good reason not to test the condition outside of the regular expression? I can't think of an adequate way to do this right off the bat without look-behinds. Actually, they are scary.
Could you please describe the problem in its entirety? From experience, when someone asks me “how to build a regular expression” in 90% of cases, the initial statement of the problem helps to find a more adequate solution, although often through a different regular expression.

Answer 2

So
(\d+\.){20}

Answer 3

(\d+\.){1,20}
but like this?

Answer 4

Is this your IP?

Answer 5

Your string 111.223.123.12 looks a lot like an ip address. It is he? Or just an example?

Answer 6

Why does it have to be done regularly? Can't you just check the length of a string without a regular expression?

Answer 7

^(?=.{0,20}$)(\d+\.)+$