1

00:00:01,780 --> 00:00:02,440

Hello everyone.



2

00:00:02,440 --> 00:00:06,160

So in the last video we discussed about different types of inheritance.



3

00:00:06,220 --> 00:00:06,660

Okay.



4

00:00:06,700 --> 00:00:10,350

In this video we will discuss about the fifth type.



5

00:00:10,600 --> 00:00:16,060

So in this ruling we will discuss about the fifth type of inheritance which is the hybrid inheritance.



6

00:00:16,060 --> 00:00:17,200

So what is the meaning of hybrid.



7

00:00:17,200 --> 00:00:18,690

Hybrid means mix.



8

00:00:18,700 --> 00:00:18,970

OK.



9

00:00:19,000 --> 00:00:24,970

So in order to achieve hybrid inheritance what we will do we will mix that for types of inheritance



10

00:00:24,970 --> 00:00:26,080

that we want to distribute.



11

00:00:26,080 --> 00:00:27,280

Let us take an example.



12

00:00:28,060 --> 00:00:34,720

So in we are Duplessis let's say see that it would even be now at this time I am using multiple in that



13

00:00:34,720 --> 00:00:37,660

it is now be inherited classy.



14

00:00:37,870 --> 00:00:45,060

So I am using my beloved inheritance here and now I am using hierarchal inheritance.



15

00:00:45,100 --> 00:00:45,620

OK.



16

00:00:45,670 --> 00:00:47,280

Let's take one more example.



17

00:00:47,320 --> 00:00:54,540

So suppose I have a class A now B and C both class in that it's from Class A.



18

00:00:55,100 --> 00:00:55,690

Okay.



19

00:00:55,750 --> 00:01:01,670

And now we have a class B which inherits from both Class B and Class C.



20

00:01:02,220 --> 00:01:04,470

OK so what will happen here is simple.



21

00:01:04,470 --> 00:01:10,420

So what over the structure of the guess over the list trophy the structural failure will be very simple.



22

00:01:10,480 --> 00:01:18,830

It will have only a specific properties then since being named from classy it will have a some B specific



23

00:01:18,830 --> 00:01:20,030

properties.



24

00:01:20,030 --> 00:01:21,420

So this is B.



25

00:01:21,710 --> 00:01:31,130

And the structure of C will be some C specific properties and a so where the structure of the the structure



26

00:01:31,130 --> 00:01:33,050

of the will be very simple.



27

00:01:33,050 --> 00:01:38,520

So this is D day inherits from Class B and C.



28

00:01:38,840 --> 00:01:46,420

So this is B B inherits from Class A and B specific properties.



29

00:01:46,510 --> 00:01:58,020

Similarly c c inherits from Class A C specific properties and then we will have some D specific properties.



30

00:01:58,020 --> 00:02:04,690

Okay now what will happen since Class D has two copies of glass.



31

00:02:05,310 --> 00:02:05,630

Okay.



32

00:02:05,650 --> 00:02:07,810

Glasby has two copies of glossy.



33

00:02:07,880 --> 00:02:10,760

So what it will do in future it will create ambiguity.



34

00:02:10,760 --> 00:02:12,370

How do we create ambiguity.



35

00:02:12,380 --> 00:02:18,580

Suppose this class he has a brain function inside public section.



36

00:02:18,630 --> 00:02:23,540

Okay so what will happen here we have a brain function.



37

00:02:23,750 --> 00:02:26,870

And similarly this is also a spring function.



38

00:02:26,870 --> 00:02:32,500

Now if we want to call print function that compiler will get confused which print function to call okay.



39

00:02:32,720 --> 00:02:35,170

So it will create ambiguity.



40

00:02:35,180 --> 00:02:37,640

Now let us take an example.



41

00:02:37,640 --> 00:02:45,260

So suppose we have a weekly class now both the classes God and truck they inherited from this working



42

00:02:45,260 --> 00:02:45,660

class.



43

00:02:45,680 --> 00:02:52,860

Okay so this is truck class and now bus class inherits from both car and truck.



44

00:02:53,390 --> 00:02:53,800

Okay.



45

00:02:53,900 --> 00:03:01,120

So this type of structure this is called a diamond problem and regret and be used in future.



46

00:03:01,130 --> 00:03:04,640

So this diamond problem it is a very well known problem.



47

00:03:04,640 --> 00:03:06,490

Okay so what will happen.



48

00:03:06,530 --> 00:03:07,760

So as we can see above.



49

00:03:08,330 --> 00:03:11,030

So this is also a diamond problem.



50

00:03:11,480 --> 00:03:15,260

So in Diamond problem we have ambiguity also.



51

00:03:15,470 --> 00:03:21,130

We have multiple copies Okay so due to multiple copies we will have ambiguity.



52

00:03:21,370 --> 00:03:26,760

Okay now our aim is to avoid multiple copy our aim is to avoid ambiguity.



53

00:03:26,760 --> 00:03:32,040

Okay now let's see in code how we can achieve the diamond problem and how we can resolve the diamond



54

00:03:32,040 --> 00:03:32,810

problem.



55

00:03:32,880 --> 00:03:41,800

Okay so let's say in called So this is our code we have of the class and inside the working class we



56

00:03:41,800 --> 00:03:50,290

have a default constructor a paramedic's constructor print function and a destructor Okay so we have



57

00:03:50,290 --> 00:03:53,950

a class card which inherits from the vehicle class.



58

00:03:53,950 --> 00:03:57,450

So we have a default constructor and a destructor.



59

00:03:57,680 --> 00:03:57,990

Okay.



60

00:03:58,450 --> 00:04:04,450

Similarly we have a class truck this also inherits from the working class and we have a constructor.



61

00:04:04,450 --> 00:04:12,760

Now here comes class bus it generates from class truck and also it generates from class got and it also



62

00:04:12,760 --> 00:04:14,370

inherits from class truck.



63

00:04:14,500 --> 00:04:18,110

And this is simple a constructor okay.



64

00:04:18,320 --> 00:04:20,790

So now our domain column is ready.



65

00:04:20,930 --> 00:04:28,230

And now let us first create the object of bus class okay so must be.



66

00:04:28,400 --> 00:04:30,180

Now what will happen if I add on this file.



67

00:04:30,200 --> 00:04:33,530

What would be the order of the constructor call let us try to understand



68

00:04:37,960 --> 00:04:50,370

so we have the class both the God and the truck class they inherited from the class and similarly class



69

00:04:50,370 --> 00:04:52,230

was inherited from God and truck.



70

00:04:52,500 --> 00:04:55,330

Okay so I am creating an object Busby.



71

00:04:55,410 --> 00:04:58,950

So what will happen first of all what was the order of the constructor call.



72

00:04:59,250 --> 00:05:01,970

So here we will write our order.



73

00:05:02,820 --> 00:05:04,100

So what will happen before.



74

00:05:04,380 --> 00:05:12,030

As soon as we create an object of must be we will go to God class to call it to call its constructor



75

00:05:12,030 --> 00:05:16,590

first by car class first because I have written car first and then truck.



76

00:05:16,590 --> 00:05:23,310

Okay so if we all know that before the bus class construct every bit called its parent class constructor



77

00:05:23,310 --> 00:05:25,830

will be called since there are two buildings car and truck.



78

00:05:25,920 --> 00:05:30,810

So first car class constructively record by car class because I have written God first.



79

00:05:31,110 --> 00:05:36,170

So God bless constructively required we will reach the car class and the parent of quiet classes vehicle.



80

00:05:36,360 --> 00:05:40,980

So we will go head and then the vehicle left constructor will call it first.



81

00:05:40,980 --> 00:05:47,250

So first of all we could constructively be called then we will reach to God again.



82

00:05:47,250 --> 00:05:54,110

Now the car at last constructed will be called then we will reach the bus and then we will each truck.



83

00:05:54,390 --> 00:05:59,940

So before calling their top class our class constructor truck will call its parent class constructor



84

00:05:59,970 --> 00:06:00,900

which is we call.



85

00:06:01,230 --> 00:06:05,720

So now that we like construct it will be called then we will come back to Truck.



86

00:06:05,730 --> 00:06:08,090

So now the top class constructor will be called.



87

00:06:08,160 --> 00:06:12,480

And now finally the best class constructor will be called okay.



88

00:06:12,480 --> 00:06:14,850

So this will be the order of the cost of protocol.



89

00:06:14,850 --> 00:06:15,260

Okay.



90

00:06:15,390 --> 00:06:20,520

So we can see here the working class constructor will be called twice.



91

00:06:21,300 --> 00:06:25,480

Okay so let us try to verify our output.



92

00:06:25,850 --> 00:06:26,960

So let's send this file



93

00:06:31,640 --> 00:06:32,780

so this is the order.



94

00:06:34,970 --> 00:06:37,700

So this is the order the first vehicle then God.



95

00:06:37,700 --> 00:06:39,870

Then again vehicle then truck and then bus.



96

00:06:39,910 --> 00:06:40,150

OK.



97

00:06:40,160 --> 00:06:42,470

So do not look like the order of the destructor.



98

00:06:42,470 --> 00:06:42,770

Why.



99

00:06:42,770 --> 00:06:45,530

Because we have not created district for every class.



100

00:06:45,530 --> 00:06:45,970

Okay.



101

00:06:46,100 --> 00:06:50,180

But we know the order of district will be just the opposite of the Order of the inheritance.



102

00:06:50,210 --> 00:06:54,150

Okay so the order of destructor will be the opposite of this.



103

00:06:54,180 --> 00:06:59,040

Okay.



104

00:06:59,280 --> 00:07:00,890

Now let's do one more thing.



105

00:07:00,900 --> 00:07:03,420

Let us try to call brain function.



106

00:07:03,420 --> 00:07:03,680

Okay.



107

00:07:03,690 --> 00:07:04,770

So be dot



108

00:07:07,930 --> 00:07:14,130

surveys the brain function so bus Gus doesn't have any print function proc doesn't have brain function.



109

00:07:14,160 --> 00:07:15,990

Similarly car doesn't have brain function.



110

00:07:15,990 --> 00:07:21,630

Actually it has print function but we have commanded it out so we could gloss has the print function



111

00:07:21,960 --> 00:07:26,620

since the print function is public it is accessible to every derived class.



112

00:07:26,670 --> 00:07:26,970

Okay.



113

00:07:27,000 --> 00:07:29,670

So be has access to the print function.



114

00:07:29,700 --> 00:07:32,540

So that means we will not get an error due to accessibility.



115

00:07:32,630 --> 00:07:35,460

Let's see whether we will get in that error or not.



116

00:07:35,460 --> 00:07:40,090

So we will get we will definitely get an error and that it will be due to ambiguity.



117

00:07:40,110 --> 00:07:43,400

So what is happening what is the structure of bus class.



118

00:07:43,560 --> 00:07:45,600

So the structure of bus class is quite simple



119

00:07:48,450 --> 00:07:50,280

so this is our bus class.



120

00:07:50,280 --> 00:07:53,350

So bus class inherits from car and truck.



121

00:07:53,580 --> 00:08:03,670

So this is car and this is truck so inside the car plus I have the class we can.



122

00:08:03,700 --> 00:08:07,690

And similarly to class inherits from the class.



123

00:08:07,750 --> 00:08:14,740

So this vehicle class has brain function and this working class is also high Sprint function.



124

00:08:14,740 --> 00:08:17,410

Basically both the print function are exactly the same.



125

00:08:17,410 --> 00:08:18,000

Okay.



126

00:08:18,010 --> 00:08:20,290

So when will run the file.



127

00:08:20,290 --> 00:08:26,650

We will get in the red line number 17 that print function is present in multiple base classes.



128

00:08:26,710 --> 00:08:27,100

Okay.



129

00:08:27,100 --> 00:08:28,640

There will be ambiguity problem.



130

00:08:28,660 --> 00:08:30,580

I'll get compiler will get confused.



131

00:08:30,580 --> 00:08:32,020

Which print function to call.



132

00:08:32,040 --> 00:08:34,600

Although both the print function are exactly the same.



133

00:08:34,600 --> 00:08:36,900

But compiler will get confused.



134

00:08:36,970 --> 00:08:45,420

Okay so now let's send this file to see so we are getting an error and that is due to ambiguity.



135

00:08:45,420 --> 00:08:48,720

You can see that and also so print is ambiguous.



136

00:08:48,750 --> 00:08:49,670

Okay.



137

00:08:50,130 --> 00:08:52,030

Now how can we resolve this header.



138

00:08:52,140 --> 00:08:54,660

So there are two ways to resolve this error.



139

00:08:54,690 --> 00:08:59,150

First way is to add a print function inside the bus glass.



140

00:08:59,190 --> 00:08:59,660

Okay.



141

00:08:59,760 --> 00:09:07,350

So as soon as we will as soon as we write a print function inside the bus glass and beauty problem will



142

00:09:07,350 --> 00:09:15,660

be resolved widely as all because in the last session because in the last radio we have seen that whenever



143

00:09:15,740 --> 00:09:23,520

a whenever a class so in the last few days we have seen that whenever a class as a function of its own



144

00:09:23,550 --> 00:09:28,460

then first of all we will check the bus class only since the bus class has the print function.



145

00:09:28,470 --> 00:09:30,450

We will not go to its parent class.



146

00:09:30,580 --> 00:09:30,860

OK.



147

00:09:30,870 --> 00:09:32,930

So there will be no ambiguity.



148

00:09:32,970 --> 00:09:36,660

So when I call this function without print this brain function will be called.



149

00:09:36,860 --> 00:09:37,430

Okay.



150

00:09:37,470 --> 00:09:38,700

And our output will be buzz.



151

00:09:39,780 --> 00:09:41,070

Okay so let's send this file



152

00:09:44,580 --> 00:09:46,880

so I would output this bus.



153

00:09:46,890 --> 00:09:48,180

Okay.



154

00:09:48,180 --> 00:09:51,690

Now that and other way to solve this problem is to specify the class.



155

00:09:51,690 --> 00:09:52,310

Okay.



156

00:09:52,440 --> 00:09:55,020

We will specify the class since both.



157

00:09:55,030 --> 00:09:56,450

So what is the structure.



158

00:09:56,640 --> 00:09:59,340

So let us write the structure here.



159

00:09:59,340 --> 00:10:00,990

Okay so let's write the structure.



160

00:10:00,990 --> 00:10:02,440

So we have.



161

00:10:03,360 --> 00:10:18,800

So we have this class bus this bus glass inherits from God and from truck and this is the class.



162

00:10:18,880 --> 00:10:20,920

So this is also a vehicle.



163

00:10:21,430 --> 00:10:25,090

This will go class has a print function.



164

00:10:25,090 --> 00:10:27,740

This will allow us all to this brain function.



165

00:10:27,790 --> 00:10:31,890

And now let us comment out the brain function of the bus class.



166

00:10:31,900 --> 00:10:36,310

Okay now bus class doesn't have in the print function.



167

00:10:36,340 --> 00:10:39,020

So when I write B dot print what will happen.



168

00:10:39,220 --> 00:10:44,100

Obviously we will get an error because two print functions are already there.



169

00:10:44,140 --> 00:10:44,430

Okay.



170

00:10:44,440 --> 00:10:48,380

So to resolve this error the second way was to specify the class name.



171

00:10:48,640 --> 00:10:52,350

So either we have to specify the car or we have to specify the truck.



172

00:10:52,360 --> 00:10:57,160

We cannot specify the vehicle because both car and truck as we call it will not so on what ambiguity



173

00:10:57,160 --> 00:10:58,000

problem.



174

00:10:58,000 --> 00:11:01,390

So we have to specify our data card or either truck.



175

00:11:01,480 --> 00:11:01,890

Okay.



176

00:11:02,020 --> 00:11:03,920

So let us specify the car.



177

00:11:04,240 --> 00:11:09,570

So we will write we dart card and then scope resolution operator okay.



178

00:11:09,880 --> 00:11:16,040

So let's send this file so now I would put this vehicle.



179

00:11:16,060 --> 00:11:19,280

Okay so our problem is resolved.



180

00:11:19,280 --> 00:11:20,090

Now what if



181

00:11:22,870 --> 00:11:27,830

notify and comment the print function of the car plus.



182

00:11:27,870 --> 00:11:29,480

So what will happen now.



183

00:11:29,490 --> 00:11:30,010

Okay.



184

00:11:30,120 --> 00:11:37,400

So what happened is we have this glass cut this glass also has a brain function of its own.



185

00:11:37,410 --> 00:11:40,660

Now what will happen if I write.



186

00:11:40,930 --> 00:11:45,410

So if I write B dot God it's called resolution or greater print.



187

00:11:45,480 --> 00:11:46,650

What will happen.



188

00:11:46,650 --> 00:11:58,230

So when I write B dot God scope resolution operator and then the print function and if I had eight B



189

00:11:58,230 --> 00:12:07,150

dart print and if I had eight B dart school resolution operator and print.



190

00:12:07,840 --> 00:12:11,380

So what will the output of all these three lines.



191

00:12:11,380 --> 00:12:15,120

Okay so first of all world output of this line.



192

00:12:15,120 --> 00:12:21,030

So first of all this line will throw us at it via debt because inside the bus function we do not have



193

00:12:21,030 --> 00:12:23,910

any print function since we do not have brain function.



194

00:12:23,910 --> 00:12:30,060

We will go to its parent class which is God in print and now there will be ambiguity why ambiguity because



195

00:12:30,150 --> 00:12:33,670

there are now three print functions okay.



196

00:12:33,770 --> 00:12:35,240

That t print functions now.



197

00:12:35,240 --> 00:12:37,240

So there will be ambiguity.



198

00:12:37,340 --> 00:12:38,920

So obviously this will throw us at it.



199

00:12:39,890 --> 00:12:40,520

Okay.



200

00:12:40,520 --> 00:12:45,490

Now let's see this beat out God school resolution operator and print.



201

00:12:45,560 --> 00:12:49,260

Now what do we do it very clearly specifies go to go of class.



202

00:12:49,310 --> 00:12:51,900

And since the kind class has print function of its own.



203

00:12:52,200 --> 00:12:54,700

So this print function will be called.



204

00:12:54,940 --> 00:12:55,600

Okay.



205

00:12:55,640 --> 00:12:59,050

And B Da plUG Scott resolution operator print will happen.



206

00:12:59,120 --> 00:13:00,660

We will go to class.



207

00:13:00,680 --> 00:13:02,690

Class do not have print function of its own.



208

00:13:02,690 --> 00:13:06,430

So it will go to its parent class parent class s print function.



209

00:13:06,590 --> 00:13:09,310

So print this time this print function will be called.



210

00:13:09,320 --> 00:13:09,980

Okay.



211

00:13:09,980 --> 00:13:16,170

So it will call this one and it will call this one.



212

00:13:16,420 --> 00:13:25,600

Okay let's send this file so what we are output now this brain function will be called Card print function.



213

00:13:25,600 --> 00:13:33,990

Okay let's send this file so we can see here num dials num gives.



214

00:13:34,000 --> 00:13:34,300

Okay.



215

00:13:34,330 --> 00:13:36,290

So now I'm biased num gives and colors.



216

00:13:36,310 --> 00:13:42,580

So God brain function is being getting call okay.



217

00:13:42,750 --> 00:13:47,380

Now we have cleared them beauty but still there is one big problem.



218

00:13:47,460 --> 00:13:47,720

Okay.



219

00:13:47,730 --> 00:13:48,990

So what is the big problem.



220

00:13:49,920 --> 00:13:51,310

So ambiguities is old.



221

00:13:51,390 --> 00:13:55,740

Now we all know ambiguities is all but there is still one very big problem that we need to handle.



222

00:13:56,220 --> 00:14:03,660

And the very big problem is that there are two copies clause D will have two copies of glass.



223

00:14:04,170 --> 00:14:16,630

Okay so this is glass D and inside the glass V I have glass B glass B has a and similarly class C has



224

00:14:16,690 --> 00:14:16,910

a.



225

00:14:17,710 --> 00:14:22,230

Okay so here we have two copies of glass a.



226

00:14:22,340 --> 00:14:24,100

Now we have to solve this problem.



227

00:14:24,170 --> 00:14:24,870

Okay.



228

00:14:25,010 --> 00:14:27,110

I definitely we want only one copy.



229

00:14:27,110 --> 00:14:29,260

We need only one copy of glass a.



230

00:14:29,320 --> 00:14:29,590

Okay.



231

00:14:29,600 --> 00:14:32,620

So we have to avoid this copying how can we avoid this copying.



232

00:14:32,630 --> 00:14:35,240

We can use the keyboard what tool.



233

00:14:35,240 --> 00:14:35,720

Okay.



234

00:14:35,840 --> 00:14:37,330

So there is a keyword.



235

00:14:37,420 --> 00:14:39,030

What tool.



236

00:14:39,360 --> 00:14:40,350

Now let's see.



237

00:14:40,350 --> 00:14:48,600

Well we have to write a tool to solve this copy problem so glass card before writing the public.



238

00:14:48,600 --> 00:14:55,790

We will write virtual and similarly for track class we have to write what tool



239

00:14:58,820 --> 00:14:59,360

okay.



240

00:14:59,400 --> 00:15:00,930

Now what this virtual will do.



241

00:15:01,020 --> 00:15:07,050

So this virtual will ensure that class D will now have only one copy of class A.



242

00:15:07,200 --> 00:15:09,960

Okay so let's come in this out.



243

00:15:11,070 --> 00:15:13,950

So now we are creating an object of bus B.



244

00:15:14,130 --> 00:15:18,780

So if I will run this file what with the order of the constructor call let us try to understand



245

00:15:22,940 --> 00:15:34,320

so I have this working class then car and truck so guide classes in editing class classical but we have



246

00:15:34,320 --> 00:15:36,120

a keyboard virtual okay.



247

00:15:36,240 --> 00:15:39,180

We are in editing the class but we have a keyword virtual.



248

00:15:39,180 --> 00:15:41,310

So what what should we do.



249

00:15:41,310 --> 00:15:45,180

Let's try to understand and we have bus here.



250

00:15:45,180 --> 00:15:45,900

Okay.



251

00:15:45,960 --> 00:15:48,090

So C must be.



252

00:15:48,210 --> 00:15:55,220

So what will happen so first of all where the best class will do it will go to its parent class to call



253

00:15:55,220 --> 00:16:01,880

its default constructor so will reach GA class since the Cairo class is virtually inheriting from the



254

00:16:01,940 --> 00:16:02,720

working class.



255

00:16:03,140 --> 00:16:04,240

So what will happen.



256

00:16:04,340 --> 00:16:11,330

Bus class will call the vehicle class bus class will call the constructor their default constructor



257

00:16:11,330 --> 00:16:18,290

of the vehicle class so the order of the the order of the constructor call will be first this vehicle



258

00:16:18,290 --> 00:16:22,580

glass constructor will be called and who will call boss class constructor will be called.



259

00:16:22,670 --> 00:16:28,800

This cannot call that God cannot call because they are inheriting the vehicle glass of water surely



260

00:16:28,820 --> 00:16:30,820

so they cannot call the constructor.



261

00:16:30,860 --> 00:16:37,670

Okay so first it will be called victory in this construct and will be called then God class and then



262

00:16:37,670 --> 00:16:41,030

track class and then finally the best class constructor will be called.



263

00:16:41,210 --> 00:16:49,580

So as we can see here the class construct will be called only once okay and who will call but will call



264

00:16:49,970 --> 00:16:53,670

neither God nor truck.



265

00:16:53,750 --> 00:16:56,530

Okay so let's let's see the.



266

00:16:56,630 --> 00:17:04,920

Now let's run this file so as you can see first recalled car truck and then bus.



267

00:17:05,010 --> 00:17:10,730

OK so because construct based call only once not twice alert was called place.



268

00:17:10,850 --> 00:17:11,130

OK.



269

00:17:11,180 --> 00:17:12,990

But here it will recall only once.



270

00:17:13,010 --> 00:17:15,780

And who will call boss class will call.



271

00:17:15,810 --> 00:17:19,610

OK so what is the concept of a virtual based class.



272

00:17:19,610 --> 00:17:19,840

OK.



273

00:17:19,850 --> 00:17:21,590

So how we're actually helping here.



274

00:17:23,160 --> 00:17:27,780

What is the purpose of like what is the meaning of this virtual based class.



275

00:17:27,780 --> 00:17:28,270

Okay.



276

00:17:28,380 --> 00:17:32,650

So earlier what was happening this car plus



277

00:17:35,530 --> 00:17:38,170

has object as object of virtual class.



278

00:17:38,170 --> 00:17:41,980

So this was really a situation before using the virtual keyboard.



279

00:17:41,980 --> 00:17:48,060

Now we are using what tool show vehicle glasses now a virtual based class.



280

00:17:48,070 --> 00:17:49,080

So what will happen now.



281

00:17:50,910 --> 00:17:57,710

So this is got a glass This is glass.



282

00:17:57,960 --> 00:18:05,200

So earlier the gardener truck glass they have the actual vehicle object but now they will have a pointer.



283

00:18:05,520 --> 00:18:14,360

Similarly truck will have a pointer to the vehicle object they now have a pointer to difficult object



284

00:18:14,630 --> 00:18:22,550

earlier they have the vehicle object but now they have a pointer to the vehicle object.



285

00:18:22,550 --> 00:18:22,900

Okay.



286

00:18:22,910 --> 00:18:35,060

And really the structure of the bus so Elliot bus only has got an object but no bus will have vehicle



287

00:18:35,060 --> 00:18:38,690

object it will have cart object and it will have object.



288

00:18:38,960 --> 00:18:45,170

So that's why a bus will call the vehicle's last constructor no ID card neither car neither truck.



289

00:18:45,320 --> 00:18:53,330

OK so bus will be able to call the world class constructor working class constructor and God and I cannot



290

00:18:53,330 --> 00:18:59,670

call the vehicle class constructor because they only have pointer and not the actual object.



291

00:18:59,930 --> 00:19:02,510

Okay so now we are avoiding the copy.



292

00:19:02,570 --> 00:19:02,970

Okay.



293

00:19:02,990 --> 00:19:06,290

So now we had a wedding copy we only have one copy.



294

00:19:06,290 --> 00:19:09,810

There are not multiple copies.



295

00:19:10,000 --> 00:19:10,690

Okay.



296

00:19:10,930 --> 00:19:12,920

Now let's see one more thing.



297

00:19:12,930 --> 00:19:13,200

Okay



298

00:19:17,420 --> 00:19:17,730

okay.



299

00:19:17,740 --> 00:19:23,420

So now let's come in out the cost of the default construct of the class.



300

00:19:23,450 --> 00:19:25,000

Now what will happen.



301

00:19:25,010 --> 00:19:25,530

Okay.



302

00:19:25,610 --> 00:19:30,890

So since we have better merge based constructor so the default construct better if we could class is



303

00:19:30,890 --> 00:19:33,970

not visible to us okay.



304

00:19:34,030 --> 00:19:37,510

So what will happen.



305

00:19:37,570 --> 00:19:40,020

So now we have to call the Better based constructor.



306

00:19:40,030 --> 00:19:44,230

OK so since the default constructor weaker class is not visible.



307

00:19:44,230 --> 00:19:50,590

So now we have to call this better my place to construct explicitly because implicitly a child class



308

00:19:50,590 --> 00:19:54,450

can only call the default constructor of its parent class.



309

00:19:54,630 --> 00:19:54,870

Okay.



310

00:19:54,880 --> 00:20:01,190

So if you will run this file must be let us on this file so we are getting an error and let's see that.



311

00:20:01,190 --> 00:20:12,110

What is that it so the error is so bad it is Truck Bus and God so we are getting an error in all the



312

00:20:12,110 --> 00:20:16,990

three classes got bus and wave struck.



313

00:20:17,090 --> 00:20:18,190

So this is truck.



314

00:20:18,610 --> 00:20:22,550

Okay so we are getting an error in all the three classes.



315

00:20:22,550 --> 00:20:28,070

So what is happening here is so in the last three videos I told you that a class can only call the constructor



316

00:20:28,070 --> 00:20:29,950

of its immediate parent.



317

00:20:30,230 --> 00:20:35,810

But here the bus class is calling construct of its grandparent.



318

00:20:35,840 --> 00:20:37,930

Okay so this is a special case.



319

00:20:37,970 --> 00:20:38,270

Okay.



320

00:20:38,270 --> 00:20:43,460

I'm repeating myself in their libidos I told you that a class can only call the concept of profits immediate



321

00:20:43,460 --> 00:20:44,040

parent.



322

00:20:44,140 --> 00:20:48,460

But here the bus glass is quoting the construct proffered grandparent.



323

00:20:48,590 --> 00:20:52,820

Okay but only in this case because we are using the virtual keyword.



324

00:20:52,820 --> 00:20:53,300

Okay.



325

00:20:53,420 --> 00:20:56,710

We are making the weekend class as virtual base class.



326

00:20:56,750 --> 00:21:01,790

Okay so only in this case class can call the constructor of its grandparent.



327

00:21:01,790 --> 00:21:06,580

Okay so this type of inheritance is also known as what actually inheritance.



328

00:21:06,590 --> 00:21:06,850

Okay.



329

00:21:06,890 --> 00:21:10,040

So this type of an identity also known as virtual inheritance.



330

00:21:10,040 --> 00:21:12,020

Now let's solve this problem.



331

00:21:12,020 --> 00:21:15,790

So how can we solve this problem since we do not have any default constructor.



332

00:21:15,800 --> 00:21:23,190

We have to call it bottom at best constructor explicitly so class got so with the help of initialization



333

00:21:23,190 --> 00:21:28,890

list we can let's say three okay.



334

00:21:28,900 --> 00:21:32,530

So let's spend the value of Z here



335

00:21:37,480 --> 00:21:39,230

so I am bringing the value of Z also.



336

00:21:39,320 --> 00:21:39,790

Okay.



337

00:21:40,860 --> 00:21:42,320

Now I am bringing the value of Z.



338

00:21:42,330 --> 00:21:44,950

You will understand in some time so.



339

00:21:44,990 --> 00:21:45,420

Truck



340

00:21:48,620 --> 00:21:54,210

the call and let's say the value is for we are calling the paramedics construct.



341

00:21:54,260 --> 00:21:54,880

Okay.



342

00:21:54,920 --> 00:22:01,630

And similarly we have to do for bus also because bus also has the object of because class.



343

00:22:01,650 --> 00:22:02,400

Okay.



344

00:22:02,700 --> 00:22:09,710

This is a special case we had a we had a class can call the concept of its grandparent Okay and let's



345

00:22:09,720 --> 00:22:10,710

say the value is



346

00:22:13,630 --> 00:22:15,090

and let's say the value is five.



347

00:22:15,240 --> 00:22:16,470

Okay.



348

00:22:17,100 --> 00:22:19,650

So value 3.



349

00:22:19,650 --> 00:22:23,270

Value for value 4 and value 5.



350

00:22:23,690 --> 00:22:23,960

Okay.



351

00:22:23,960 --> 00:22:29,830

And I am bringing the value of Z here Okay let's send this file



352

00:22:33,970 --> 00:22:37,870

so you can see what is the value getting printed 5.



353

00:22:38,140 --> 00:22:40,140

This is the proof variable used 5.



354

00:22:40,150 --> 00:22:42,050

Here okay.



355

00:22:42,160 --> 00:22:44,020

So here we are using 5.



356

00:22:44,020 --> 00:22:45,430

So this is the proof.



357

00:22:45,670 --> 00:22:46,020

Okay.



358

00:22:46,060 --> 00:22:53,070

So we have proved that bus glasses is calling the victim class constructor and not the car in the truck.



359

00:22:53,330 --> 00:22:59,840

Okay so I hope now you understand where this diamond problem and how we can use virtual keyword and



360

00:23:00,290 --> 00:23:03,070

how to resolve ambiguity and how to avoid copy.



361

00:23:03,080 --> 00:23:03,530

Okay.



362

00:23:03,590 --> 00:23:03,980

Thank you.