WEBVTT 00:00.410 --> 00:07.100 Okay, so next up, I'd like us to learn about the types of the function arguments and the optional 00:07.100 --> 00:09.680 return types that you can define. 00:09.920 --> 00:13.970 Now let's go back to the data types as well. 00:14.090 --> 00:15.620 Let me zoom in. 00:16.490 --> 00:22.760 So we're gonna create this example in a separate file now because this time we're gonna be talking about 00:22.760 --> 00:24.140 the explicit types. 00:24.140 --> 00:28.640 And how can we enforce the type to be explicit. 00:28.640 --> 00:35.720 Which means that you shouldn't really be able to pass strings when the function expects integers. 00:35.750 --> 00:40.460 So let's jump to the code editor and see what does it all mean. 00:41.630 --> 00:52.370 So let's make a types file inside the functions folder, add a PHP tag, and let's define a super simple 00:52.370 --> 00:53.060 function. 00:53.060 --> 00:59.420 But this time we're gonna have types for the arguments and for the return type of that function. 00:59.420 --> 01:02.580 So this function is super simple. 01:02.580 --> 01:03.990 It's just adding. 01:03.990 --> 01:11.370 Now obviously we have an operator for the adding operation in PHP, but that's just an example. 01:11.370 --> 01:14.070 So let's not think about it too much. 01:14.070 --> 01:21.180 And when we add the values we have basically one value that we add to the other. 01:21.180 --> 01:26.910 So let's define two arguments of the type integer a and b. 01:27.030 --> 01:31.080 And obviously the return type of that has to be integer. 01:31.080 --> 01:32.790 So let's also define that. 01:32.790 --> 01:33.840 It's super simple. 01:33.840 --> 01:37.590 We're just going to return a plus b. 01:38.100 --> 01:46.020 So as I said let's ignore the fact that creating such function has zero sense because this operation 01:46.020 --> 01:54.630 exists I just want to present something okay, so why don't we just echo the result of add and let's 01:54.660 --> 01:57.000 add 5 to 3. 01:59.040 --> 02:00.060 Let's run it. 02:00.100 --> 02:04.270 Um, let's make sure I am in the functions folder and run types. 02:04.510 --> 02:05.020 PHP. 02:05.620 --> 02:07.930 So that's the expected result. 02:07.960 --> 02:08.890 Eight. 02:09.100 --> 02:13.210 But what happens if I would pass a string here? 02:13.210 --> 02:17.410 That would be a number but passed as the string type. 02:17.410 --> 02:19.210 So let's run this again. 02:19.510 --> 02:22.690 PHP types PHP and we still got the result back. 02:22.720 --> 02:23.320 Eight. 02:23.350 --> 02:26.950 Now why won't we vardump that instead. 02:26.950 --> 02:29.500 So we will also see the return type. 02:30.010 --> 02:35.110 Let's do var dump and rerun that again. 02:35.110 --> 02:40.210 So the result of the function is an integer value is eight. 02:40.210 --> 02:41.680 So what happened here. 02:41.680 --> 02:45.580 We've defined the types and we were explicit about that. 02:45.580 --> 02:52.000 So what's the point of defining the types if you can pass a string to a function. 02:52.000 --> 02:55.390 So let me explain what's happening here. 02:56.410 --> 03:05.060 So generally the type declarations were introduced in PHP around the version five, and they were just 03:05.090 --> 03:06.380 added gradually. 03:06.800 --> 03:10.040 PHP was moving really slow in the past. 03:10.070 --> 03:15.650 Now a lot more features are added and a lot more quicker and a lot more often. 03:15.650 --> 03:18.350 But that wasn't the case back then. 03:18.350 --> 03:23.360 So you've got the types, but they weren't strictly enforced. 03:23.660 --> 03:34.940 Now, since PHP version seven, another option was added that was strict types, which basically meant 03:34.940 --> 03:43.520 that you had to tell PHP that if you define the types you really mean that that you are not just signaling 03:43.550 --> 03:51.590 what would be nice to pass to a function, but that a value of this specific type has to be passed to 03:51.620 --> 03:52.340 a function. 03:52.340 --> 03:58.400 Otherwise there will be an error, a runtime error, and the program will stop. 03:58.430 --> 04:01.510 So to actually enforce this. 04:01.540 --> 04:08.560 To enforce those types, you need to add a declaration at the top of the file which is looking exactly 04:08.560 --> 04:09.280 like this. 04:09.280 --> 04:17.320 You write declare and you type strict underscore types equals one. 04:17.350 --> 04:25.570 By the way, that's one of the well, one of the couple statements, one of the exceptions in PHP that 04:25.570 --> 04:28.270 does not require semicolon. 04:28.360 --> 04:33.490 So I've mentioned that before that you don't have to add semicolon everywhere. 04:33.520 --> 04:37.570 That's one of the cases where you don't have to do that. 04:37.600 --> 04:40.390 Another is for example namespace declarations. 04:40.390 --> 04:44.860 But we're gonna get to that when we'll be talking about classes. 04:44.860 --> 04:49.000 But I prefer to just add those semicolons everywhere. 04:49.030 --> 04:51.280 My personal preference. 04:51.700 --> 04:54.160 Now let's see what will happen now. 04:54.790 --> 04:58.300 Now we have strict types, but only for this file. 04:58.300 --> 05:04.220 So you need to understand that that you have to add this declaration in every single file. 05:05.210 --> 05:11.870 Now, when I run the same code and I'm passing a string to this function, I get a fatal error. 05:11.900 --> 05:18.440 And I would really suggest to declare the strict types to be enabled, because that's the whole point 05:18.440 --> 05:27.410 of having types, the added security, making sure that no one will accidentally pass something that's 05:27.410 --> 05:35.030 of a different type, which forces PHP to use type coercion, which might have some unexpected side 05:35.030 --> 05:35.870 effects. 05:35.870 --> 05:44.090 So this type coercion, that was fine when PHP was used to create apps that maybe weren't so mission 05:44.090 --> 05:45.260 critical. 05:45.290 --> 05:53.480 But these days when we are creating software that, for example, handles money well, you probably 05:53.480 --> 06:04.140 want to have all the security that you can get So to make it work, I need to change it back to five. 06:04.980 --> 06:08.610 And now we get the working function. 06:09.540 --> 06:11.280 So why we are here? 06:11.280 --> 06:15.180 Let's do an experiment and let's pass a float value. 06:15.180 --> 06:22.710 But we are gonna pass something that is, at least for us, exactly the same. 06:22.740 --> 06:25.020 So I'm going to pass 5.0. 06:25.020 --> 06:28.260 And let's see what PHP is gonna say about that. 06:29.760 --> 06:30.090 Okay. 06:30.090 --> 06:32.190 So that's a fatal error. 06:32.250 --> 06:39.720 So as you see if that's an integer, it has to be an integer, not something that looks like an integer 06:39.720 --> 06:42.300 or is almost an integer. 06:42.330 --> 06:44.520 It has to be an integer. 06:44.520 --> 06:47.370 And it really has to be of this type. 06:47.370 --> 06:54.870 So if you really want to pass this as an integer, you can typecast it using this int operator. 06:54.900 --> 06:57.090 Then it's fine.