Ruby Programming Tutorial - 24 - Regular Expressions in Loops Video Lecture | Introduction to Coding with Ruby - Back-End Programming

alright guys welcome to your 24th Ruby
Tesoro
and in addition to just using regular
expressions in simple statements you can
also scan a string and actually extract
whatever you pulled out and use it in
some way so what I'm going to be doing
is I'm going to be teaching you guys
about the scan method and what this does
is it looks for a regular expression
extracts and all I'm going to be doing
is printing out on the screen so say
that I don't know you want it to but
it's basically like looping through a
string and we wanted to print out three
characters at a time well let's go ahead
and do this right now the first thing we
need is a string and I'm just going to
set mine equal to variable a equals not
equals - that would be messed up Wow
Bucky is the greatest beautiful now that
we have that variable a we can go ahead
and call the scan method on it now the
scan method is a parameter it takes a
regular expression so remember the first
thing I said that all regular
expressions start and end with forward
slashes so let's get those out of the
way right now now in my regular
expression the only thing well we know a
couple symbols but we know the period
means any single character so let's go
ahead and write three periods which
means it's basically going to scan
through the string while Bucky is the
greatest and it's going to rip it apart
three characters at a time now what we
can do is we can actually store those
pieces in variable this might look a
little bit familiar to you store it in
the variable B and now that we have that
let's just go ahead and print or puts B
on the screen so you remember whenever
we use loops we could store whatever we
extract it in a variable and then print
it out on the screen let's go ahead and
do that right now and see what we get
Wow Bucky is the greatest kind of it's a
little bit choppy but basically that's
what we're doing right now our regular
expression said okay this means any
three characters and clearly a character
also includes spaces as well so even
though you can't see even though it's
not a number or a letter of a space in
computer programming is
actually a character so what if you
wanted to UM you know do the same thing
or something similar to this but you
didn't want to include these spaces now
spaces are also called white spaces so
if I say white spaces and spaces I
pretty much mean the same thing well
instead of these periods dot dot dot
what we would want to use is another
symbol in regular expressions which is
backslash s backslash s backslash s so
this is going to do is basically this
now remember a backslash s is basically
a non whitespace character any number
any letter is going to match backslash s
now let me go ahead I keep saying black
flush but you know what I mean
so basically let's go ahead and run this
and see what we get
Wow Bucky the great and it kind of
messes up it doesn't say wow Bucky is
the greatest without any spaces and this
is why take a look at our original
shrink Wow Bucky is the greatest now
what we said is basically loop through
this or scan through this and rip it
apart whenever you find the three non
whitespace characters well the reason
that it doesn't print out things like is
is whenever it comes to is it says okay
this is only two non whitespace
characters we have one two but we didn't
match our third parameter basically so
that's why it doesn't print out things
like this so again basically for this
tutorial I want to tell you that just
remember this just take this away and
you'll be good a period whenever you're
working in regular expressions is any
character it can be a space it can be a
letter it can be a number it's any
character a backslash s is only a non
whitespace character so it can be
letters and numbers but it can't be
spaces now you can use these in
combination between forward slashes to
make patterns now in the upcoming
tutorial I'm going to show you guys I'm
going to be showing you guys different
ways where you can use these patterns
and also in different things other than
loops like decision-making
and stuff like that but for now thank
you guys for watching and we're get
subscribing I'll see you guys in the
next video