WEBVTT 00:00.410 --> 00:01.700 Hello, my name is Stephan. 00:01.700 --> 00:05.940 And in this lecture of our course, we will continue our project on ADTs. 00:05.960 --> 00:07.340 So let's get started. 00:19.240 --> 00:23.440 So we will add a virtual method named Makesound. 00:23.440 --> 00:30.970 And the virtual method is a method that has no implementation yet and only has the definition. 00:31.000 --> 00:32.290 Also known as the interface. 00:32.290 --> 00:39.640 So the derived class has to add the implementation to the virtual method using the override keyword. 00:39.640 --> 00:42.760 So or else the compiler will complain about it. 00:42.760 --> 00:50.260 So after we have a new animal class, we will make a class named dog that derives from the animal class. 00:50.470 --> 00:57.010 So here we will add the animal here. 00:57.310 --> 00:59.200 So after that we will. 00:59.200 --> 01:00.250 As you can see, we have. 01:01.270 --> 01:02.230 This animal. 01:04.120 --> 01:10.420 And we have the constructor get give name and get name so we don't actually need the give name here 01:10.420 --> 01:17.500 since we are giving name using the constructor here, but we can also use that in case if in if we need 01:17.500 --> 01:17.620 it. 01:17.620 --> 01:19.390 But we don't need it for now. 01:20.230 --> 01:26.070 And after that we will create a new class class here, dog. 01:26.080 --> 01:29.470 And this is we're going to make it the public class. 01:33.140 --> 01:36.320 Public, actually. 01:37.140 --> 01:44.370 Yes, we will make it a public class so the class dog will implement the public animal. 01:44.670 --> 01:46.620 Public animal. 01:47.360 --> 01:52.130 And after that we will write our class. 01:52.160 --> 01:58.430 So in this case, we're going to use the public keyword and we will forward the constructor arguments. 01:58.430 --> 02:06.440 So the dog here, we're going to use the string name and here we're going to use the. 02:07.460 --> 02:08.420 Animal name. 02:08.930 --> 02:10.040 Animal and name. 02:10.040 --> 02:17.330 We will forward this the string name to our animal name here. 02:17.330 --> 02:21.170 So animal name and here. 02:22.950 --> 02:27.150 After that, we will also need to implement the interface. 02:27.150 --> 02:35.310 So here we're going to make the string here, make sound, make sound and we will it. 02:36.370 --> 02:39.410 And the sound is going to be, of course, the woof, woof. 02:39.460 --> 02:44.620 Like this is what the dog sound like when they are woof, woof here. 02:45.230 --> 02:49.010 So here we will use a return. 02:49.220 --> 02:50.270 Woof, woof. 02:52.380 --> 02:53.160 Wolf, here. 02:53.790 --> 02:56.130 And as you can see, we got an error here. 02:56.280 --> 03:01.230 So a virtual member can be marked override here. 03:01.620 --> 03:03.060 So now. 03:04.820 --> 03:05.800 No problem here. 03:06.610 --> 03:07.180 Obviously. 03:08.960 --> 03:12.110 And this is because the string makes sound. 03:12.150 --> 03:15.980 All right, Here, we'll have to return Wufoo and make it like that. 03:16.550 --> 03:17.780 And here. 03:23.570 --> 03:26.480 Class dog public here. 03:26.480 --> 03:29.240 And this is going to return the woof woof here. 03:30.620 --> 03:32.480 Now we will write it like that. 03:33.170 --> 03:35.810 We're going to create a new class named Doc here. 03:36.140 --> 03:41.480 Doc is going to be let's name our doc is the. 03:42.400 --> 03:42.910 Here. 03:43.930 --> 03:45.160 Hound here. 03:46.950 --> 03:49.350 And see out. 03:51.010 --> 03:52.660 Dot get name. 03:53.940 --> 03:58.860 Get name is gonna be is barking. 03:59.880 --> 04:00.900 So. 04:00.900 --> 04:01.740 And after that. 04:01.740 --> 04:04.890 See out, See out. 04:08.580 --> 04:10.890 Dog not make sound. 04:11.850 --> 04:12.240 Of course. 04:12.240 --> 04:13.710 It's the Maxent. 04:13.740 --> 04:16.560 We'll return the woof woof here. 04:16.710 --> 04:24.150 So make sound is going to be, uh, the Our hound is barking and woof, woof. 04:24.180 --> 04:24.630 Here. 04:27.540 --> 04:29.280 We have a problem here. 04:31.250 --> 04:35.560 We have string name and animal we passed here. 04:36.550 --> 04:38.260 Which is gonna to overeat. 04:43.210 --> 04:48.910 And here we will add the virtual interface in our. 04:48.910 --> 04:54.920 As you can see, we have an error here and we will add the virtual interface to our animal class. 04:54.940 --> 05:01.290 So now after the animal constructor here, we will add the virtual virtual string. 05:01.300 --> 05:07.390 So we, we can also use the integer because but we will get an error because this returns string here. 05:07.390 --> 05:10.810 So we need to use the virtual type here. 05:10.840 --> 05:16.540 The string and the string is going to be makesound. 05:17.630 --> 05:21.110 So the interface has the implemented in derived class here. 05:21.290 --> 05:24.560 So zero for example. 05:24.710 --> 05:26.810 And here. 05:28.010 --> 05:28.460 We have. 05:29.450 --> 05:34.680 So actually now we can also run our application now and see. 05:34.700 --> 05:36.890 As you can see, Hound is barking. 05:36.920 --> 05:38.030 Woof, woof here. 05:38.210 --> 05:42.640 So now we have two classes, the animal class here, actually. 05:42.650 --> 05:53.350 Let's see here we have the animal class as the base class, and we have the dog class as a derived class. 05:53.360 --> 06:00.770 So as shown here, the dog class has to implement the make sound method. 06:00.860 --> 06:07.940 And it has been defined as a virtual method here in the animal class. 06:07.940 --> 06:09.410 So if we delete this. 06:11.720 --> 06:13.970 And as you can see, we got an error here. 06:15.290 --> 06:16.820 We can create the haunt here. 06:18.170 --> 06:18.650 So. 06:22.440 --> 06:32.010 And the instance of the dog class can also invoke the getName method, even though it's not implemented 06:32.010 --> 06:40.020 inside the dog class, since derived class derives all the class behavior to itself. 06:40.380 --> 06:47.520 So if you run this code again, we will see this output here. 06:47.520 --> 06:50.020 So let's actually compile and run inside here. 06:51.540 --> 07:01.050 CLS or plus plus Main.cpp output dog dot x and dog dot x here. 07:01.050 --> 07:04.440 And as you can see here, hound is barking. 07:04.440 --> 07:05.190 Woof, woof. 07:05.190 --> 07:05.570 Here. 07:06.530 --> 07:08.000 Uh, that's our. 07:08.010 --> 07:15.660 And again, we can say that the dog ADT has two functions and they are the these are the two functions. 07:15.660 --> 07:18.990 They are getName and make sound functions. 07:18.990 --> 07:25.920 But as you can see, we have no getName functions inside the animal class and the. 07:27.120 --> 07:31.510 Another necessary comment will be discussed in next lecture about ADT. 07:31.580 --> 07:33.720 So I'm waiting you in next lecture.