Susanna Learns Regex Part I

ARRRRGH so don't ask me to explain what regex actually is; okay fine it stands for regular expressions; at the end of a long and hard workday I finally got down to doing some regex. Regex is basically a way of matching strings I guess.

Or other things.

It's basically a tool for pattern matching. 

Literals

A literal in regex is when you literally match something precisely.

It doesn't have to be the full thing; it can just be a part of something; but it does have to match it exactly.

bananas will match with bananas

usanna will match with susanna

monkey will match with i am a monkey and i litearlly like to climb all over things in my house and i literally like to eat bananas... not saying if any of that is true... or not...

Alternation

Alternation in regex allows us to match for multiple things.

You can use a pipe delimiter to match for two or more things.

alan turning|maragaret elaine hamilton

will allow us to match for both

i love alan turing 

and 

i love margaret elaine hamilton

Character Sets

Arrrgh, these are a little bit more complicated! These allow you to denote for multiple potential characters or options at once.

Let's check for all the potential spellings of Susanna:

su[sz]anna?

? indicates for optionality!

Wildcards

"Sometimes we don't actually care WHAT characters are in a text, just that there are SOME characters!". Codecademy said it best (I am doing their Regex course, I think it's free).

. just means a character

Filtering only for seven-letter names? ....... will match susanna and alferdo and aurelia and alberto alike!

I am .. years old will match I am 29 years old and I am 30 years old... yep this is a thing rn.

What if we want a full stop? We use an escape character \.

I am .. years old\. will make sure that we end my new age with a full stop! I am 30 years old. This has been a major life change for me...