RegexOne - Learn Regular Expressions - Problem 2: Matching phone numbers

Problem 2: Matching phone numbers

Validating phone numbers is another tricky task depending on the type of input that you get. Having phone numbers from out of the state which require an area code, or international numbers which require a prefix will add complexity to the regular expression, as does the individual preferences that people have for entering phone numbers (some put dashes or whitespace while others do not for example).

Below are a few phone numbers that you might encounter when using real data, write a single regular expressions that matches the number and captures the proper area code.

Exercise 2: Matching phone numbers

Task	Text	Capture Groups
capture	415-555-1234	415
capture	650-555-2345	650
capture	(416)555-3456	416
capture	202 555 4567	202
capture	4035555678	403
capture	1 416 555 9292	416

Solution

To grab the area code from the phone numbers, we can simply capture the first three digits, using the expression (\d{3}).

However, to match the full phone number as well, we can use the expression 1?[\s-]?$?(\d{3})$?[\s-]?\d{3}[\s-]?\d{4}. This breaks down into the country code '1?', the captured area code '$?(\d{3})$?', and the rest of the digits '\d{3}' and '\d{4}' respectively. We use '[\s-]?' to catch the space or dashes between each component.

Solve the above task to continue on to the next problem, or read the Solution.

Lesson Notes

	abc…	Letters
	123…	Digits
	\d	Any Digit
	\D	Any Non-digit character
	.	Any Character
	\.	Period
	[abc]	Only a, b, or c
	[^abc]	Not a, b, nor c
	[a-z]	Characters a to z
	[0-9]	Numbers 0 to 9
	\w	Any Alphanumeric character
	\W	Any Non-alphanumeric character
	{m}	m Repetitions
	{m,n}	m to n Repetitions
	*	Zero or more repetitions
	+	One or more repetitions
	?	Optional character
	\s	Any Whitespace
	\S	Any Non-whitespace character
	^…$	Starts and ends
	(…)	Capture Group
	(a(bc))	Capture Sub-group
	(.*)	Capture all
	(abc\|def)	Matches abc or def