jimburton/ci646-regex

CI646 Regex lab

Firstly, familiarise yourself with the documentation for the Java regex package java.util.regex: https://docs.oracle.com/javase/7/docs/api/java/util/regex/Pattern.html.

As you complete the problems below, you can test your regexes at http://regex101.com.

This repository has a solution branch where you can compare your solution to mine. No cheating! ;)

1. Modify the class PhoneNumbers.java so that it validates UK landline phone numbers. Valid numbers take one of the following forms:

   • A 6 digit local number, e.g. 123456. Local numbers may not begin with a zero.
   • An area code, which may be surrounded by brackets, followed by an optional space, followed by a valid local number. Area codes consist of 5 digits and begin with the digits 01. E.g.,
     • 01273 123456
     • [phone]
   • The international dialling code, +44, followed by a valid area code from which the leading digit has been stripped, followed by a valid local number. Numbers using the international dialling code may not contain spaces. E.g. [phone].

2. Modify your program to validate dates in one of the following forms:

   • dd-Mon-yyyy, where dd is a valid day of the month (01 to 31), yyyy is any four digits and Mon is a string from the set { Jan, Feb, Mar, Apr, May, Jun, Jul, Aug, Sep, Oct, Nov, Dec}.
   • dd/mm/yyyy, where dd is a valid day of the month, mm is a valid month (01 to 12) and yyyy is any four digits.
   • mm/dd/yyyy, where mm is a valid month, dd is a valid day of the month and yyyy is any four digits.

   Each of these patterns have things in common (e.g. valid days of the month) -- make separate variables for the parts of the patterns so you don't repeat yourself. Surrounding each sub-pattern in grouping brackets will ensure that they still work when you combine them.

   If the input string is a date in the form dd-Mon-yyyy, your program should print “Valid date”.

   If the input string is a date in the form dd/mm/yyyy but not mm/dd/yyyy, your program should print “Valid UK date”. If the input string is a date in the form mm/dd/yyyy but not dd/mm/yyyy, your program should print "Valid US date". If the input string matches both dd/mm/yyyy and mm/dd/yyyy (e.g. 01/01/2020) your program should print “Valid date in the form xx/xx/xxxx”. For all other input, your program should print “Invalid date”.

If you want to become a regex wizard the book Mastering Regular Expressions by Jeffrey Friedl is very good: http://regex.info/book.html.