Regex not preventing wrong input from being processed

Question

I am trying to create a regex that only accepts 2 types of phone number inputs. The phone number inputs are (5554446666) and (+15554446666) and nothing else, so this is the regex I wrote:

Regex phoneNumberPattern = new Regex(@"^\s*(?:\+?(\d{1,3}))?(\d{7})");

The problem is when I entered just seven digits (4446666), it accepted it.

possible duplicate of [C# Regex Phone Number Check](http://stackoverflow.com/questions/8596088/c-sharp-regex-phone-number-check) — MethodMan, Mar 12 '15 at 14:51
possible duplicate of a million different regex questions. Did you try doing a [search](http://www.regexlib.net/Search.aspx?k=phone)? — Chase Florell, Mar 12 '15 at 14:52

score 1 · Answer 1 · answered Mar 12 '15 at 14:52

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Don't make the + conditional - the whole prefix group is conditional, that's how it's supposed to be. Making the + conditional means you're now supporting all phone numbers with 7-10 numbers. Oh, and put $ on the end.

answered Mar 12 '15 at 14:52

Luaan

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Thank you, the first 3 didn't even pay close attention to the question. – nahaelem Mar 12 '15 at 15:05

score 1 · Accepted Answer · answered Mar 12 '15 at 15:00

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Something like this should return the required phone numbers:

(\+1\d{10})|(\d{10})

answered Mar 12 '15 at 15:00

Eduardo Ramos

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Regex not preventing wrong input from being processed

2 Answers2