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PHP Function Default Arguments6:58 with Hampton Paulk
Sometimes if an argument is not passed through, and you want it to have a starting value, no matter what, this is where a default argument will come to your assistance.
Having a good understanding of what a function argument means, 0:01 we can now talk about another important component known as default arguments. 0:03 Sometimes, if an argument is not passed through, but 0:08 you want the function to have a starting value no matter what, 0:11 this is where a default argument will come to your assistance. 0:15 Now you can see it's just hello, dollar sign, name. 0:18 Then, we'll simply add name equals and 0:22 then whatever our definition for the default argument should be. 0:26 In this case we'll just do friend that way I can pass through an argument like this. 0:30 So I'll say hello and then Mike. 0:34 That way it'll say Hi, Mike, how's it going? 0:37 But if I choose to just pass through hello, 0:40 remember we didn't define anything outside of the function scope like before, but 0:43 now it's gonna say Hi, friend, how's it going? 0:47 Now what if we wanted to do multiple default arguments, 0:50 just like in our greet function? 0:54 We'll simply add the same way we did it before, which is equals friend and 0:55 then equals morning on time_of_day and name, respectively. 1:00 This way I can still call, greet Mike afternoon and 1:04 get, Hi, Mike, good afternoon. 1:08 But if I pass with no arguments whatsoever, it'll just say, Hi, friend, 1:11 good morning. 1:16 Now let's say we wanted to make an argument predefined as optional. 1:17 Well the way we do that is in the same way we've done default arguments. 1:22 Let's say for instance, I don't really need you to provide me a time of day. 1:26 Well, let's do that by simply eliminating it set to morning and 1:30 make it equal to Null. 1:35 This way, we have to check inside the function if time of day is set. 1:37 So we'll check if time_of_day, and 1:42 then we'll surround our previous statement with an if and an else. 1:44 Now, if time_of_day is equal something other than null, 1:49 it'll say hi name and then good time_of_day. 1:52 But we need to provide an else as well. 1:56 So what we'll do is just say echo hello comma name. 1:59 And close that statement with a semicolon. 2:04 This way I can still say greet Mike afternoon and get, Hi, Mike, 2:07 good afternoon. 2:12 But I'm also able to just pass through Mike to our 2:13 greet function without the time of day and we'll end up getting this back. 2:16 Hi, Mike. 2:20 So now let's talk a look here in Workspaces on how to 2:22 work with default arguments. 2:25 So far we have had some arguments here, we've passed through arguments, 2:27 if we don't pass an argument we'll end up getting an error. 2:32 So what we'll need to do is create default arguments so 2:35 that way we don't get the errors when we forget to pass through. 2:38 We'll also look at how to make arguments optional. 2:42 So, let's start with creating a function that will show a little 2:45 bit of info about someone and maybe who they are or a title. 2:48 So let's start with creating that function. 2:53 So function and then get info. 2:56 'Kay. And we're gonna have two argument here, 3:01 one is gonna be the name and next one is going to be the title. 3:03 'Kay? 3:07 Then open and close our curly braces. 3:09 So now we have our function. 3:12 Now inside of this function what we want to do is just echo a string. 3:14 So echo, and then we'll go ahead and 3:17 do double quotes even though we're going to output some variable information. 3:20 So let's start with name and then has arrived, 3:26 they are with us as a and then title. 3:32 So this way in a string format if I was to say get info. 3:38 And then pass through two strings. 3:45 So let's say Mike and Mike is a frog. 3:46 Okay. So we have multiple arguments here and 3:51 we have one is the name and next will be in the title. 3:54 So notice they are in the same order as they were defined on line three. 3:58 So I'm going to go ahead and save this and then take out, take a look at the preview. 4:01 So here we see it says Mike has arrived. 4:06 They are with us as a frog. 4:09 Okay. That seems perfectly reasonable. 4:11 Let's go back over and say that we forget to type in frog. 4:13 We just save this and hit refresh. 4:19 It'll say Mike has arrived. 4:21 They are with us as a, nothing. 4:22 There's a blank. 4:25 Well we don't want that so 4:25 we're gonna need to define some kind of default argument here. 4:27 So let's go back over to our code and then say, get info, title, and name. 4:31 Well let's say we want to define a title to start with so 4:37 we say title equals, and this is where our default is. 4:41 And we'll say, friend. 4:45 All right, now save it. 4:46 And if we don't use title as an argument it should come through as friend. 4:50 So we'll go ahead and hit our Preview. 4:55 Refresh. 4:58 And there it says, Mike has arrived, they with us as a friend. 4:59 Which is great. 5:02 Okay. 5:03 Now what if we wanted to take, and make the title completely optional? 5:04 Well, that's pretty easy to do. 5:09 All we need to do is remove equals friend, and just simply say equals null. 5:12 Okay, this way it's not gonna report back any kind of errors or notices for us. 5:17 But we need to do something a little different. 5:23 Cuz otherwise, it's just gonna come up with that blank again. 5:24 So let's create an if statement to test whether or not title exists. 5:27 So we'll say if, and then we'll say title. 5:31 We don't need to see if it's true or anything like that. 5:36 Just simply saying if title, make sure that it exists. 5:38 It's anything other than null. 5:41 All right. So if title. 5:43 We're gonna open and close our curly braces, oh and then else. 5:45 We're going to do something different. 5:48 All right. 5:50 Well I'm actually going to actually use this line. 5:51 So, I'm gonna cut it, and then head back up here and paste it in. 5:53 Make sure my tabs are good. 5:57 Okay. 5:58 And then here if we don't have a title, we want to echo something different. 5:59 So, echo and then name has arrived, and then welcome. 6:02 Perfect, all right. 6:10 So now we close that with a semicolon to end our statement. 6:12 So if we go down and 6:17 run what we have currently by going to our preview button and refreshing it. 6:18 Now it says, Mike has arrived, welcome. 6:22 Because on line 13 here we did not pass through an argument. 6:24 But if we do pass through an argument here such as let's say, frog. 6:29 Save it. 6:36 And then refresh our preview. 6:36 Now it will say, Mike has arrived, they are with us as a frog. 6:39 So, in order to get a optional argument we can simply 6:42 pass through the default argument as null, or we can pass through a string or 6:45 any kind of value we want to use as our default argument 6:50 in the argument definition of the function such as in line three. 6:54
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