WEBVTT 00:00.080 --> 00:04.910 Next up, let's cover variadic function arguments. 00:04.910 --> 00:09.710 So so far we've covered the required and optional arguments. 00:09.800 --> 00:18.140 If you define variadic arguments on a function, then your function doesn't really have the predefined 00:18.170 --> 00:20.180 amount of arguments. 00:20.180 --> 00:29.540 It means that once you define this variadic argument, which basically is defined by adding three dots 00:29.540 --> 00:39.920 before the argument name, this function accepts unlimited amount of arguments, and everything that 00:39.920 --> 00:48.560 you pass after the required arguments will be passed to this function as an array. 00:49.280 --> 00:51.170 That's the theory. 00:51.200 --> 01:00.200 Now let's see how this works in practice and when this is useful and why it might be useful. 01:00.200 --> 01:04.980 So let's begin by creating another file for the specific case. 01:05.010 --> 01:07.500 Let me call this variadic. 01:07.530 --> 01:08.310 PHP. 01:10.170 --> 01:17.040 As usual, let's add a PHP tag and we're going to begin by defining a new function. 01:17.040 --> 01:25.230 Let's have something simple a sum function that for every single argument passed to this function, 01:25.230 --> 01:28.860 will just return the sum of all of them. 01:29.070 --> 01:33.030 So how do you define a variadic argument? 01:33.060 --> 01:36.330 You add three dots and give it a name. 01:36.330 --> 01:38.190 Let's call it numbers. 01:38.190 --> 01:45.000 So as I've said before this will be passed to this function as an array. 01:45.030 --> 01:45.480 Okay. 01:45.510 --> 01:49.410 So let's calculate the sum of all of those numbers. 01:49.620 --> 01:51.600 So we did that before. 01:51.600 --> 01:55.710 We can use the for each loop for this case. 01:55.710 --> 02:01.230 Or we can also use a predefined function existing in PHP. 02:01.260 --> 02:01.800 Maybe. 02:01.800 --> 02:03.270 Let's go with the loop. 02:03.930 --> 02:11.790 Define the sum variable and then do for each numbers as number. 02:13.650 --> 02:17.970 And let's add the number to the sum. 02:20.730 --> 02:24.630 The dollar sign and return the sum. 02:24.960 --> 02:33.630 So if a function accepts variadic arguments, it means that you can either pass 0 or 5 or 10 or 20 arguments 02:33.630 --> 02:34.140 to it. 02:34.170 --> 02:43.170 Let's try to call this function first with nothing, and maybe let's vardump everything so we see what's 02:43.170 --> 02:44.790 the exact result. 02:45.630 --> 02:50.910 Okay so I'm inside the functions directory so I can call variadic PHP. 02:52.740 --> 02:57.840 So we've got zero because well this was an empty array. 02:58.620 --> 03:02.760 Now let me also var dump the numbers. 03:04.060 --> 03:08.650 So we can confirm that we actually have received an array. 03:09.310 --> 03:10.330 There it is. 03:11.950 --> 03:12.160 Okay. 03:12.190 --> 03:15.430 So next up let's actually add some arguments. 03:15.430 --> 03:19.870 Let me add one argument and run this function again. 03:21.310 --> 03:29.500 So this time this is what this function received an array where we have just one item an integer five. 03:29.590 --> 03:31.990 So that's the obvious result. 03:32.470 --> 03:32.830 Okay. 03:32.860 --> 03:40.690 So now let's add some more three maybe four or even five arguments. 03:42.580 --> 03:44.260 So you see how it works. 03:45.040 --> 03:49.810 We can now pass any amount of arguments to that function. 03:49.810 --> 03:53.530 And this function will receive an array. 03:55.390 --> 03:55.630 Okay. 03:55.630 --> 03:57.460 So let's have another example. 03:57.490 --> 04:02.290 Let's mix the required arguments with variadic arguments. 04:02.320 --> 04:13.960 So let's define another function, call it introduce team, where you're gonna accept the team name 04:14.320 --> 04:17.320 and members. 04:19.330 --> 04:24.460 So here we've got one required argument that should be a string. 04:24.460 --> 04:29.560 We are not working with types yet, but well, we basically expect the team name here. 04:29.560 --> 04:34.510 And then you can have well any amount of members. 04:35.950 --> 04:43.030 So here we're gonna just echo the team name like that. 04:43.150 --> 04:48.520 And next up we're gonna just list all the members. 04:48.820 --> 04:54.220 So it's the first time we're gonna use a built in function that does something with arrays. 04:54.220 --> 04:57.130 This is something you might really use quite often. 04:57.130 --> 04:58.780 It's called implode. 04:58.780 --> 05:05.570 So what this function does is it converts an array to a string. 05:05.600 --> 05:08.240 The first argument is the glue. 05:08.240 --> 05:12.860 So what should be added after every single array element? 05:12.890 --> 05:15.590 Let's add a comma and a space. 05:15.620 --> 05:18.260 And the second argument has to be an array. 05:18.260 --> 05:22.370 And we know that members is a variadic argument. 05:22.370 --> 05:24.680 Thus it's an array. 05:25.760 --> 05:29.720 So let's also join that with a new line character. 05:29.900 --> 05:33.890 As usual we might want to dump the members. 05:33.890 --> 05:36.500 So we see that it is indeed an array. 05:36.530 --> 05:37.430 And that's it. 05:37.430 --> 05:41.870 This function doesn't return anything, it just echoes something. 05:41.870 --> 05:44.090 Let me call this now. 05:44.570 --> 05:47.390 So this first parameter is required. 05:47.390 --> 05:51.380 So maybe let me call this a team. 05:52.910 --> 05:59.900 And then we have John Mr. T maybe that's enough. 05:59.900 --> 06:04.880 And now let's just call PHP variadic PHP. 06:05.120 --> 06:07.340 And this is our team. 06:07.520 --> 06:12.500 And that's the argument, the variadic argument we've received. 06:12.680 --> 06:15.950 It's an array because we have well, it's always an array. 06:15.950 --> 06:23.480 But it contains two elements because we've passed two elements after the required argument. 06:23.480 --> 06:25.430 And that's the output. 06:27.350 --> 06:27.650 Okay. 06:27.650 --> 06:33.380 So that was an example of mixing the required arguments with variadic arguments. 06:34.550 --> 06:37.760 Next up let's introduce the type hinting here. 06:37.760 --> 06:42.320 So previously I've said that we should be using strict types. 06:42.320 --> 06:43.490 Let's do that. 06:44.840 --> 06:49.880 So we define declared the strict types equals one. 06:49.910 --> 06:53.090 I'm adding the semicolon even though it's optional. 06:53.090 --> 06:57.890 And now how can we make every item in this array. 06:57.920 --> 07:01.280 Well maybe an integer with the sum. 07:01.280 --> 07:05.270 This actually makes sense. 07:05.270 --> 07:14.160 So essentially you can add the type before the variadic parameter variadic argument, and this would 07:14.160 --> 07:22.950 force every single element passed to this function, to this variadic argument to be an integer, which 07:22.980 --> 07:27.330 essentially would force us to have an array of integers. 07:27.330 --> 07:32.430 And if you would try to pass something else, you're gonna have an error. 07:33.600 --> 07:35.280 So we've got this example here. 07:35.280 --> 07:39.690 And if I just run it, it should run fine. 07:39.690 --> 07:49.020 But if I'm going to change this to a string, then we've got a fatal error because it needs to be of 07:49.020 --> 07:59.940 type int as this type before this variadic argument defines the type for every single variadic argument. 08:00.000 --> 08:07.530 So since this function only has this variadic argument, then everything that you pass to it need to 08:07.560 --> 08:09.330 be an integer. 08:12.360 --> 08:12.630 Okay. 08:12.630 --> 08:16.620 So also let's make sure that we have types everywhere. 08:16.620 --> 08:21.270 So in this case in the team that's a string members. 08:21.270 --> 08:23.580 Well obviously this would be names. 08:23.580 --> 08:31.350 So we require every single member to be a string not a number or an array or anything else. 08:31.350 --> 08:39.570 And keep in mind or notice that this function here does not return anything with such cases. 08:39.570 --> 08:43.560 We should also have a return type that would be void. 08:43.830 --> 08:49.080 That's the return type that you add when the function does not return anything. 08:49.110 --> 08:52.350 And why this is useful? 08:52.350 --> 08:58.260 Well, if I would try to return something instead of echoing it, let's see what will happen. 09:00.540 --> 09:03.690 As you see, I even have an error right away. 09:03.900 --> 09:10.930 And it says that a void function must not return a value. 09:11.140 --> 09:18.670 So if you don't plan to return a value from a function, well, you should add the void type for extra 09:18.700 --> 09:19.840 safety. 09:20.200 --> 09:24.070 Let's see if everything works fine here. 09:24.100 --> 09:26.320 Yes, it works fine. 09:26.890 --> 09:35.170 If I would pass a number instead of John, then this should also trigger an error. 09:35.470 --> 09:36.460 And it did. 09:36.910 --> 09:39.790 So let's bring it back to the working state. 09:41.530 --> 09:48.430 Now, finally, what if we have an array like our, like an array of numbers? 09:48.430 --> 09:58.030 And we'd like to pass this elements from this array into a sum function to calculate a sum. 09:59.140 --> 10:00.640 Can we do that easily? 10:00.670 --> 10:07.630 Well, maybe the brutal way would be to just pass every single argument explicitly like this. 10:07.660 --> 10:09.700 So first element of our array. 10:09.700 --> 10:15.730 a second element of array, etc. but there is obviously a better way. 10:15.880 --> 10:19.630 So it's called unpacking arrays into arguments. 10:19.630 --> 10:21.790 So given those numbers. 10:22.450 --> 10:31.330 Let's vardump the result I can call sum and use this three dot operator on the array. 10:31.360 --> 10:33.700 That's variable or expression. 10:33.700 --> 10:41.560 And what this would do is it will take all those elements from this array and pass them as subsequent 10:41.560 --> 10:44.650 variadic arguments of that function. 10:47.020 --> 10:54.940 So if I will call this right now, we can see that I think that's this case right here. 10:55.240 --> 11:01.930 So we received an array with three integers one, two and three. 11:02.230 --> 11:04.270 So that's this case. 11:04.300 --> 11:10.360 Now you can also do this unpacking together with the regular arguments. 11:10.370 --> 11:14.930 So if I would try to introduce another theme. 11:18.080 --> 11:22.040 Maybe here I'm just going to have the members array. 11:22.670 --> 11:34.100 Um, so let me do Harry and maybe Johnny and Joe. 11:35.930 --> 11:45.500 I can call, introduce team, name the team and just unpack the members. 11:46.130 --> 11:49.100 Let's run it to see if this has worked. 11:49.100 --> 11:51.590 So this is our B team. 11:51.680 --> 11:54.590 This is what this function has received. 11:54.620 --> 11:58.430 Harry, John and Joe, that seems to be matching our array. 11:58.430 --> 12:04.550 And there is the output the members which also looks fine. 12:06.260 --> 12:06.470 Okay. 12:06.500 --> 12:15.470 So maybe one more example can we actually Mix the explicit arguments that we pass to this variadic argument 12:15.470 --> 12:19.130 with maybe unpacking the arrays. 12:19.610 --> 12:21.200 Well let's see. 12:21.200 --> 12:23.390 So let's call this function. 12:23.390 --> 12:30.740 And the way I want to call it is I'm gonna just pass some explicit values. 12:30.740 --> 12:37.160 So I'm just gonna pass those strings that will go into this variadic argument of the function. 12:37.160 --> 12:40.730 And I also add unpacking at the end. 12:41.900 --> 12:43.640 Will this work. 12:44.210 --> 12:45.560 Let's run the function. 12:45.590 --> 12:46.970 Now obviously this works. 12:46.970 --> 12:56.630 That's this example team B maybe I'm gonna just call it um not here team C so it's clear that's the 12:56.630 --> 13:08.120 team C and we've got those two explicit guys I've passed John and Mr. T and the members that came from 13:08.120 --> 13:08.720 the array. 13:08.720 --> 13:11.720 So as you see, we can mix those.