Beginner PHP Tutorial - 22 - Arithmetic Operators Video Lecture | PHP for Absolute Beginners: From Novice to PHP Master - Web Development

hi there this is Alex from PHP academy'
org and this is a video for the new
Boston in this video I'm going to be
talking about mathematical or arithmetic
operators inside PHP now what we mean by
arithmetic operators if you're
mathematician if you know anything about
maths you'll understand that these are
plus minus multiplication and divide in
PHP we also use modulus which you may
have heard of we use an increment and a
decrement now let me just talk you
through each one of these addition
subtraction multiplication and division
are easy modulus is where you take two
numbers for example 3 & 10 and we give a
remainder so we say 10 divided by 3 is
going to be 3 and then as a remainder 1
so a modulus of 10 and 3 or 3 & 10 would
equal 1 an increment is simply increment
a value by 1 and the decrement is simply
decreasing a value by 1 so these are
more php-based in terms of the symbols
as well as the multiplication and the
division so let's just get rid of this
and we'll go through it so the first
thing we're going to do is an example is
we're going to take two numbers and
these are going to be inside variables
in fact an actual fact at first what we
could do is we could create a variable
called sum and we can equal that to a
number and then we need to add say or
multiply or subtract another number from
it so I'm going to say 10 and from this
I'm going to add 20 remember your line
terminator at the end so all i've simply
done is straight away just put a number
in there with no no quotation marks
around it I've used the plus symbol and
I've added that to another number so now
what we can do is we can either type
echo here which I wouldn't recommend or
we could come down and echo out the
value of sum remembering your line
terminator so what we need to do now is
preview this in our browser to see if we
retrieve the result we want which should
be 30 so sum should now
this point of the program being equal to
30 and then what we can do is echo the
result by just echoing out the variable
sum okay so let's just refresh and you
can see we've got the value 30 here now
this is exactly the same with the minus
operator so at this point the value of
sum is going to equal minus 10 so let's
just double check that works by
refreshing in our browser you can see
that it's equal to minus 10 so you've
already seen an example of variables but
now we've automatically and this
variable has become a minus figure so
everything's very easy to work with we
won't run into too many errors you can
also obviously do multiplication so we
can do 10 times 20 we refreshing the
browser we get the resolve 200 which is
what we expect and that's obviously
using an asterisk we can also use our
forward slash for division so 10 divided
by 20 and we're going to receive receive
the result not 0.5 so these are basic
arithmetic operators and what would be a
lot neater and easier in this case
especially in larger programs would -
would be to have two variables so we can
have number one and I'm going to make
that say 100 and let's just get rid of
this line here and this line here so
we're starting with one variable number
one and a number two that's going to be
called up well that's going to be equal
to let's just say 50 and then I'm going
to create another variable called number
three and I'm going to equal up to two
so now what I can do is I can start to
create a long constructed and
mathematical operation if you like with
this now there's a few notes to point
out because what we want to do is we
want to as with standard maths and put
some operations some of these
mathematical operations in as a priority
so for example if I was to create a new
variable called result and I was going
to say number one added to number two
and I want to divide the whole of this
by two so all I can do is say divide
number three so what this is actually
reading out as is 100 because our
variable number one is equal to 100
added to number two
so our variable number two is equal to
50 and we're going to divide this by
variable number three which is equal to
two now in actual fact the way this
program or this result is going to work
is it's going to perform this that I've
selected in blue first then it's going
to add number one so if we think about
this reading it as a human we might say
number one at number two that's going to
be 150 and that's going to be divided by
number three which is the value of two
so we should receive the result 75 now
let's preview this in our browser now we
haven't echoed out so echo result that's
probably the most important part so
refresh we're actually retrieving the
result 125 and the reason for this is
we're performing the operation number
two divided by number three so that's 50
divided by two which is 25 and then
we're adding 100 so we're receiving the
result 125 now as with normal
mathematical operations the way we go
around this is we prioritize different
parts of our sum so we're going to
enclose this in brackets so everything
in brackets is going to be it's going to
happen first and then we're going to
divide by number three so you can see by
just the addition of these brackets we
refresh and we receive the result 75 now
let's move on to the modulus and we can
see how this works so let's have a
number one and we'll have that as 10 and
we'll have number two and that's going
to equal three now we're going to have
our result equal to number one now the
way we use modulus is with the
percentage sign so it's saying number
one mod number two so that's ten mod
three and with a result we should
receive receive number one
so we're basically saying what is the
remainder of 10 divided by three and the
remainder is one so this is useful in
some aspects of development when you
need to come up with a remainder of a
number for very various different
reasons but you'll you'll probably
experience that a bit later on now let's
just take away all the variables except
our number one what I want to do is here
is I want to create on a new line say
number one plus plus now if we were to
echo out number one now we've actually
incremented number one by one we don't
need to assign this to anything we can
just say number one plus plus and I'll
explain the reason for that in a minute
you can see that we've got oh oh yeah
echo number one sorry so if we refresh
we've got 11 now why do we need to
create this command or this variable
increment on its own the reason for that
is this is a shorthand notation of
number one equals number one plus one so
if we refresh we've got exactly the same
result
however number one plus plus is just a
quicker way of doing that now the times
that you need to use this increment and
of course we can do decrement as well
which is two minus signs as opposed to
two plus signs that will give us the
result of nine so we've decremented by 1
and the decrease by one the reason we do
this is because in loops sometimes we
need to keep track of how many times the
loop has run so we use say a figure we
might use a variable called I or a
variable called n or anything really but
we want to increment it each time the
loop happens and doing this is just a
much quicker way of instead of writing
number one equals number one plus one
obviously if you wanted to increment it
by five you would do it this way so if
we refresh that with n read
fifteen but this is these are basically
the standard operators that you're
probably going to use on a day-to-day
basis if you're programming perhaps not
the modulus but particularly the the
basic sums the addition them subtraction
multiplication division and the
increment and perhaps the decrement