Ruby Programming Tutorial - 13 - Expressions and Shortcuts Video Lecture | Introduction to Coding with Ruby - Back-End Programming

all righty guys welcome to your 13th
Ruby tutorial and in this lesson I want
to talk to you guys about expressions in
comparison operators
sounds fun huh oh it is so the first
thing I want to tell you guys is is say
that you have a variable like a and it's
equal to 3 and B and it's equal to 6
well did she know that you can also use
these variables in expressions in
expressions are pretty much like
equations so you can use a plus B plus
10 and what Ruby's going to do is it's
going to look at this as 3 plus 6 plus
10 and hopefully it comes out 19 there
you go okay so simple enough I think I
showed you guys that before but what I
didn't show you guys is this now aside
from just using variables and simple
expressions you can also assign the
value of a variable to other variables
what the heck did I just say well let me
go ahead and show you guys an example so
forget about a and B in this expression
and say we have some variable called B
now D is equal to 33
why not so okay just remember that D
equals 33 so say we have a new variable
called f and we want to assign it the
value of D so instead of just going
ahead and writing 33 like that we can
actually write it like this F equals D
now since Ruby already knows that the
value of 33 is stored in D whenever you
set F equal to D it actually stores F
equal to the value of 33 so go ahead and
hit enter and now internally Ruby is
going to know that anytime you want to
write F it's the same thing as writing
33 so go ahead and just write puts F
which pretty much prints out the value
of F on the screen and we get 33 how
awesome is that so just remember that
aside from just assigning values to
variables like a equals 3 you can also
assign variables to other variables and
what this would do is figure out the
value on the right hand side and assign
it to the variable on the left hand side
now a couple cool things that I want to
talk to you guys about is something
called shorthand
now of course you can have variable like
G in set equal to 68 and say you wanted
to make an expression like G equals G
plus 12 well what this would do is
pretty much figure out everything on the
right-hand side first so G equals 68 so
68 plus 12 of course equals 80 so now
this value is going to be 80 on the
right-hand side so whenever you press
ENTER the old value of G gets overridden
and the new value is 80 so that is
basically how you can use an old value
of variable instead of equal to a new
value of variable using a simple
expression or equation now a shorthand
for this is whenever you want to use the
old value of a variable in either add
something to it or multiply subtract
something from it you can do this so G
equals G plus 12 is the same thing as
writing G Plus excuse me
G plus equals 12 this is just a
shorthand or a faster way to write this
so just remember this one last time I'm
going to pound this in your brain g
equals g plus 12 is the exact same thing
is writing g plus equals 12 so now the
old value of G was equal to 80 now that
we add 12 to it and hit enter it's now
going to be equal to 92
do it again it's now equal to 104 do it
again now equal to 1/16
so just remember plus equals equals this
thing right here now aside from just
adding the old value of G and getting a
new value of G you can do the same thing
with minus equals x equals so for
example now that we have 116 say G armed
multiplied I keep typing capital G G x
equals 2 is going to take the old value
of G which is 1 16 times by 2 and store
it in the new value of G let's go ahead
and press ENTER and we can see the new
value is 232 so now that we put G on the
screen pretty much print out G we get to
32 so again just remember
shorthands our plus equals minus equals
x equals divide equals all that good
stuff and that is just going to save you
a little time whenever you want to
assign a new value to an old variable so
I know I said I was going to talk to you
guys about comparison operators in this
tutorial and I thought I was going to
but I'm going to save that for the next
tutorial because I want to make sure
that I get them all covered I just want
to put that in a separate tutorial but
for now thank you guys for watching
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next time