Check If Variable Is Set Video Lecture | PHP for beginners - Software Development

hello YouTube welcome to tutorial number
22 in their PHP programming series and
this is going to be a short video
hopefully and we're going to investigate
the is set function now this will be
used a lot in PHP because you'll
understand in a moment it will check if
a variable is set and it will return the
value of either true or false so let's
just make a simple PHP file and we'll
save this as is setup PHP and the way
that we use it is set function is simply
by typing is set so what we can do is we
can say m if and then when we cut if
statement here actually up here we're
going to declare that will actually
declare in here sorry so we're going to
do is say if and then inside the if the
immediate type is set and then in
brackets you need to type the variable
that you are checking if it's set or not
and in this case I'm going to check if
they variable get user is set so what
this will do is it will check if the
variable get user is set and if it is it
will return true and execute this
statement if it is not it will return
false and it will ignore all the code
inside here so when I say F is set get
user gonna echo out welcome to the
website and then we'll concatenate and
get user whoops been a bit sloppy today
okay so we'll save that and now if we go
to inset PHP and you'll see that nothing
has appeared but if we type and user
equals Bob will say welcome to the
website Bob and it's all space there but
that doesn't matter so that's simply how
to use the is set so you simply type you
can put it in an if statement in type if
and this type is set and in brackets you
need to take the variable that you're
checking is set or not and what this
will do is return either
or false so let's just go into a more
practical use for this and see I know
yep we're going to create a my
calculator using the is set so what I'm
going to do is I'm going to create a
HTML page type HTML body and then we'll
just close a HTML page right here we're
going to create a simple calculator will
call this add PHP and inside here we're
going to make a little form so form
action equals odd PHP and you should
know what this all means from a previous
tutorial and then the method is going to
be get we're going to get and then we're
going to make two different in text
boxes after going to going to amuse a
type number so import type equals number
I'm going to make one make them a bit
small size equals five and we're going
to set the name to num1 okay and then
you need to set another input box import
type the same thing type equals number
size equals five again but the name of
this one is going to be num - ok so
wanna make a little submit button here
and type equals submit I will make the
value-add just gonna just say add on the
button okay and that lend our form so if
we save this go to add dot PHP and we
have our first two acts pull up what
other plus sign there as well just make
it look a little more neater okay so now
we have our first and seven but if we
actually do anything with this nothing
happens because we haven't set it to do
anything so what we can do down here is
we can simply add them together so we'll
declare a variable num 1 is actually now
we need to start our PHP first so this
is just a little lesson you can embed
PHP inside HTML
once meant for so I will make a video
after this on the best ways to embed PHP
and HTML but for now all I need to do is
just but opening PHP tag and a closing
PHP tag in between HTML so we'll open
our PHP tag and close it I'm going to
say num 1 equal to I'm going to get up
here number one cause that and then none
- it's not equal to actually I forgot
the causation mark there my bad
and number two is going to be get none -
okay and all we need to do here say make
a new variable called total and that's
going to be m1 plus num2 okay so now all
doing here is getting the number 1 from
this textbox and num2 from this textbox
and adding them together to make the
variable total so we can just echo that
and just say echo total is concatenates
total onto that okay but if we echo this
out you'll see well actually if we just
do this now if we if we just reload this
page you'll see that says the total is
seven that's because we're actually
importing these variables into this URL
know - 3 + 2 is 4 both if we go to the
page add the PHP you'll see we have
these two ugly errors and it says the
total is 0 that's not what you want for
our page so what we can do is use the is
set function here I'll need to do is
wrap this code here inside is set so
we'll make an if statement will say if
is set and we're looking for get num1 M
yeah and say if it's set in one I need
another closing bracket there then we're
going to echo out this but the problem
with this is that we have two M two
variables we have this one get num1 but
we're also trying to call get num2 which
doesn't exist so all we need to do is as
in our logical operators we'll just
either end
animal-type is set and then get number
two
oops okay so now what that's going to do
is going to check if number one get
number one asset so with the fast text
box is been entered and then is going to
check if number two is set so if the
second is entered so if I save this
reload the page and there's a pass error
let me see what I've done wrong 112 and
I've missed out the closing bracket here
get very confused sometimes when there's
so many so save that reload and you'll
see we don't have this ugly error
anymore and if we just type four plus
but we'll get our value here okay and we
can also make another if statement to
add the value type and just type value
equals and then do our PHP here and put
the value there but I'm not going to do
that for this tutorial since this
tutorial always just aimed at you know
looking at the is set function so thanks
for watching this tutorial and hope this
helps you you will use this set function
a lot so make sure you you know get used
to it remember how it works and enjoy
the next video