Ruby Programming Tutorial - 22 - Interpolation Video Lecture | Introduction to Coding with Ruby - Back-End Programming

alright guys welcome to I believe it's
video number 22 but I'm not sure and in
this video I want to talk to guys about
interpolation using expressions or
values inside strings what the heck am I
talking about let me go ahead and just
jump right into an example say we have a
variable called a and we set it equal to
something easy like for now we have
another bearer they say variable I just
can't bear your bowls from now on now I
have another variable called B and we
set this equal to 6 so a equals 4 B
equals 6 pretty cool so now what our
boss does is he comes in and he's like
hey Bucky what I want you to do is I
want you to output on the screen four
times six equals 24 so we said okay no
problem we know this Ruby stuff we're
pretty good at it what I'm gonna do is
just put a times B equals a times B it's
just gonna go ahead and run that
expression and then it's gonna print out
4 times 6 equals 24 let me go ahead and
hit enter and oh crap it says 8 times B
equals a times B that's not what I
wanted at all what I wanted is the
actual answer 8 or excuse me 4 times 6
equals 24 so now we're scratching our
head saying how the heck are we supposed
to do that
just to write on a whole bunch of
different lines and maybe make a whole
bunch of different variables that's
gonna be a pain in the butt well there's
easy way that we can do this and it's
called interpolation interpolation is
pretty much using expressions and values
inside of a string so now let's go ahead
and rewrite our string instead of I'm
gonna go ahead and add some space
instead of just writing a times B equals
a times B that won't work because we
would end up with this we need to
interpolate these now whenever you do
that remember this use the number sign
which is the sign above the 3 on your
keyboard and the curly braces now in
between the curly braces you write
either a variable or an expression in
this case I'm just going to go ahead and
write a now instead of just printing out
a what it's going to do is this going
look what's in between these curly
braces and it's gonna get the value of
it whatever the value is that's what
it's gonna print out on the screen just
not the letter so pretty much it's gonna
print out the number four right here
because that's the value of a now I'm
just gonna go ahead and hit times pound
sign B now of course this is going to go
ahead and print out six and set it equal
to and check this out those are just
simple variables easy enough to
understand but this may not be so easy
to understand
a times B so again whenever you run this
let me go ahead and just show you guys
what happens real quick it says 4 times
6 equals 24 so that's what we wanted not
a times B equals a times B so again like
I said whenever we use interpolation
whatever is in between the curly braces
such as a times B Ruby's gonna figure
out the value of those first before
printing those to the screen and
basically that's what we're seeing right
here so instead of just printing out a
times B it's gonna say okay let me
interpolate this let me figure out the
value of a times B which is 24 and of
course that's what you want me to print
out on the screen 24 and this also works
with string variables - so say we had a
person and it's a string variable like
Bucky Roberts so now what we wanted to
do is print out something on the screen
like I love Bucky Roberts so we go ahead
and write puts I love and I know you can
just type Bucky Roberts right here but
if we go ahead and type something like
this I love person it would go ahead and
print out I love person on the screen
but we want to say I love in the person
variable which is Bucky Roberts so in
order to do that go ahead and delete
your person variable and we want to
interpolate person so I keep I keep
calling this a dollar sign it's a pound
sign sorry if I call it a dollar sign
sometimes in any ways we want to
interpolate person so now what it's
going to do is it's going to figure out
the value of person which is Bucky
Roberts it's gonna plug into the string
so it's now it's pretty much gonna print
out I
of bucky roberts so check it out i love
bucky Roberts I really do guys I really
love him he's good guy so now that is
pretty much interpolation pretty much
using either variables such as a or
expressions such as 8 times B or strings
so there you go there you have it thank
you guys for watching don't forget
subscribe don't forget that add me on
Google+ and if you have any questions
not only about this video but any other
video go ahead on my forum tnb forum
comm and now you can ask me there I'll
answer it for you if not a bunch of
people are willing to help so think eyes
for watching over go subscribe and I'll
see you later