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Information may be passed to functions through an argument list. The argument list is a comma delimited list of expressions that are evaluated from the left most item to the right. Let's look at how we can use these arguments in our functions.
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Now that we've seen the initial structure
of the function,
0:00
the next step is to talk about function
arguments.
0:03
Information may be passed to functions
through an argument list.
0:06
The argument list is a comma delimited
list of
0:11
expressions that are evaluated from the
left most item to the right.
0:13
We will pass arguments into the function
by placing them inside a parentheses,
0:18
just after the function name definition.
0:22
There are two methods of passing an
argument in regards to
0:25
how the argument value is affected by the
function.
0:28
The first is called passing by value,
which is the default in PHP.
0:32
In this case, the argument's value is not
affected at
0:37
all by the function outside of that
function's scope.
0:40
The other, which we'll not spend much time
on in this course,
0:43
is called passing by reference.
0:46
Which means that the value of an argument,
if modified by the function scope,
0:48
will be modified on the outside of that
function scope as well.
0:53
Now let's take a look at function
arguments inside of code.
0:59
So, we'll create a function that we've
already been using.
1:03
So we'll do function, hello and then open
and close.
1:06
And then we're gonna have the same in the
middle.
1:11
So, the echo statement.
1:13
And then the echo will be hello world.
1:15
Okay, exclamation point, single quote and
then semicolon.
1:20
So, this is a function that we've had
before.
1:23
And we typically call this by saying just,
hello and then open and
1:26
close our parens and then semicolon.
1:30
So let's double check this.
1:32
We'll open it up, and it is Hello, World!
1:34
Okay.
1:36
So, in order to use function arguments,
what we're going to need to do is go up to
1:37
our hello and we're going to give an
argument inside of our parentheses.
1:42
The argument we want to pass through is
dollar sign name, so $name.
1:47
And in here we wanna echo that name
instead of world.
1:53
Well, if we just did dollar sign name
here,
1:57
that wouldn't work because we have to have
it inside of double quotes.
1:59
So, as long as I do this, now name will
print to the screen.
2:02
So in order to call this with name, we
simply go down to hello and
2:06
then pass through what we're expecting
which is a string.
2:10
So I'll say Hampton.
2:13
All right, so if I save this file, go back
over to my previous screen and
2:17
refresh, now it says Hello, Hampton which
is great.
2:21
All right, go back over and let's say we
wanna say a little bit more,
2:25
so we'll just say Hello, and then How's it
going?
2:28
So it's very easy for us to update our
function and
2:34
then when we refresh, it'll be the same
thing, just with more text.
2:37
We can also change really quickly the
name.
2:40
So we'll just say, Hello, Mike.
2:43
Go back over and refresh.
2:45
Now it says Mike.
2:47
Okay, so another thing we can do here is
maybe pass multiple arguments in
2:48
by using an array.
2:54
So what we'll do is use this exact same
function but
2:57
instead of just saying hello to a name,
we'll expect it to be an array.
3:00
So we'll just call it arr for arrays.
3:05
Then we're going to use just the name
variable inside of an array.
3:09
Well, how do we know what we're gonna do?
3:14
Let's just say that every single one of
these items is going to be a name and
3:16
we want to say hello to them.
3:21
So, the first thing we're gonna need to do
is make sure that it actually is an array.
3:23
So that's very easy with a conditional
statement.
3:27
So we'll do if, and then we'll say is,
which is an internal function, array.
3:29
So if is array, and then we pass through
our actual variable, arr, or argument.
3:35
And if it is an array, then we're gonna go
and do something with that data.
3:42
else, if it's not,
3:49
what we're just gonna do is skip it
completely and just say Hello, Friends.
3:50
So we'll do, echo and then Hello, Friends.
3:56
Close that with a semicolon and that
should take care of it.
4:02
Now what we're gonna do is cut this line
for right now.
4:05
And now inside of the if statement, we
actually want to loop through our array.
4:09
So we do that with a previous statement
that we've learned which is the foreach.
4:16
So foreach, and then array, as, and then
$name.
4:20
Then we can go inside by adding our curly
braces, and
4:28
then paste in our previous code.
4:32
Tab that in for cleanliness.
4:34
And now, it will actually echo Hello, and
4:36
then use the $name here from line five,
and then pass that through.
4:39
So, Hello, name, how's it going?
4:43
Let's see if this works.
4:46
Right now it wouldn't because it would
just say,
4:48
Hello, friends, because it's not an array.
4:50
Let's actually see how that degradates.
4:52
See if it does nicely.
4:54
So we'll go ahead and hit the Preview
button.
4:55
And then you see it says, Hello, friends.
4:57
So we'll go back over and now instead of
doing just Mike here,
5:00
let's say we'll create a names array.
5:05
So we'll do names equals and then we'll
say array.
5:08
And then inside that array, we'll close it
out first.
5:12
And here we're gonna have a couple of
names.
5:17
So we'll do Hampton and we'll do a comma
on the next line just for
5:19
cleanliness, we'll say Mike.
5:24
And we'll do one more, Charley.
5:29
Okay, so we'll save that and then go back
to our Preview and hit Refresh.
5:32
Right, so you can see it's doing Hello,
Hampton, Hello, Mike and Hello, Charley.
5:36
Of course there's no new lines after each
one, so what I'll do is come up here to my
5:40
echo statement and I'll just add a HTML
break tag here, and save that.
5:45
Let's see if that fixes it for us.
5:52
Perfect.
5:54
So Hello, Hampton, Hello, Mike, and Hello,
Charley.
5:54
So there you can see, in code, how we can
take an array of values,
5:57
in this case name, and loop through them
in a function.
6:01
So, simply by calling Hello and
6:04
then passing through an array, we now have
multiple Hellos from a single function.
6:06
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