Regular Expressions

Regular Expressions (regex for short) are a way to represent patterns in strings. They aren't as bad as people make them out to be. When used on the right problem, they are a great solution.

Go to Rubular. We're going to sandbox inside it a bit to get acquainted with regex syntax. At the bottom of the page is a regex cheat sheet.
Note: Depending on the language, you may have to escape certain characters. For example, instead of a{3}, you may have to type a\{3\}.
Also, be careful with periods (.). A period means any character in regex, so you have to escape it if you want to pattern match a period.

Here are some examples of regex and matching string patterns:

a{3} => aaa
a{3,} => aaaaaaaa
[a-z] => any lowercase letter
[A-Z]{4,6} => between 4 and 6 uppercase letters, ex. FASDV
. => any character
\w\. => _.
hello\d? => hello or hello5
[a-nO-Z]* => abcOZZ

Make a regex to match each of these strings:

match 'byte academy' 3 different ways
an 8 character password, do not allow non word characters
an 8 character password that has at least 1 number and 1 capital letter
byteacademy@example.com
byte.academy@example.com
byteacademy22@example.co.uk
See if you can get all three with 1 regex, but not invalid emails (not having an @, etc...)