1
00:00:01,120 --> 00:00:04,390
Classes are containers for variables and operations.

2
00:00:04,390 --> 00:00:12,730
So that will affect the variables, as we talked about earlier, as ADTs implement encapsulation techniques

3
00:00:12,730 --> 00:00:20,650
for grouping all similar data and functions into group, the classes can also be applied to group them.

4
00:00:20,980 --> 00:00:29,050
A class has three access control sections for wrapping the data and methods and they are here.

5
00:00:29,050 --> 00:00:31,510
Let's actually this is the access.

6
00:00:33,030 --> 00:00:34,040
Controls.

7
00:00:36,260 --> 00:00:37,010
Here.

8
00:00:37,010 --> 00:00:43,390
So there there are three access controls for types and cast everything here.

9
00:00:43,400 --> 00:00:45,200
So we have the public.

10
00:00:45,530 --> 00:00:46,400
Public.

11
00:00:50,560 --> 00:00:51,430
Public.

12
00:00:51,430 --> 00:01:00,010
So public are the data and methods can be accessed by any user of the class.

13
00:01:00,040 --> 00:01:03,070
We also have the protected.

14
00:01:04,970 --> 00:01:06,470
Protect.

15
00:01:07,410 --> 00:01:07,950
That.

16
00:01:10,610 --> 00:01:18,590
So the protected they are the data and the methods can only be accessed by class methods and the derived

17
00:01:18,590 --> 00:01:20,300
classes and friends.

18
00:01:20,330 --> 00:01:23,030
We also have the private.

19
00:01:28,050 --> 00:01:36,140
The private is the data and methods can only be accessed by class methods and friends.

20
00:01:36,150 --> 00:01:41,640
So let's go back to the definition of abstraction and information hiding in the previous lecture so

21
00:01:41,640 --> 00:01:53,190
we can implement abstraction by using protected or private or not, or here private so we can use protected

22
00:01:53,190 --> 00:01:55,560
and private for implementing abstraction.

23
00:01:55,560 --> 00:02:03,690
So we can also use the implement abstraction by using private and protected keywords to hide methods

24
00:02:03,690 --> 00:02:09,750
from outside the class and implement the information hiding by using a protected or private keyword

25
00:02:09,750 --> 00:02:12,780
to hide the data from the outside the class.

26
00:02:12,780 --> 00:02:17,660
So now let's build a simple application or simple class named animal.

27
00:02:17,670 --> 00:02:24,780
So here let's right click on the project Cplusplus class animal namespace is okay.

28
00:02:24,780 --> 00:02:25,890
So yeah, here.

29
00:02:25,890 --> 00:02:27,760
So Cplusplus class here.

30
00:02:27,760 --> 00:02:30,730
Let's actually delete this definitions here.

31
00:02:36,050 --> 00:02:38,720
So this is our animal class.

32
00:02:39,050 --> 00:02:45,140
So we will create inside this animal class, we will create a private string and we will name it my

33
00:02:45,140 --> 00:02:48,380
name, private string.

34
00:02:48,380 --> 00:02:50,510
Or we will do it like that.

35
00:02:50,510 --> 00:02:51,260
Private.

36
00:02:53,100 --> 00:02:55,380
String is going to be my name.

37
00:02:55,380 --> 00:02:59,850
And also let's actually we need to import string in order to use it.

38
00:02:59,850 --> 00:03:07,140
So we will also using namespace using namespace std and import.

39
00:03:07,990 --> 00:03:09,220
Or include.

40
00:03:09,640 --> 00:03:10,840
Include.

41
00:03:12,460 --> 00:03:18,310
Include string and include the stream.

42
00:03:19,770 --> 00:03:20,210
Here.

43
00:03:20,220 --> 00:03:22,470
So this is a string my name.

44
00:03:22,470 --> 00:03:30,960
And we will also define some public variables, which is the here the public public is going to be.

45
00:03:31,590 --> 00:03:33,960
The public is going to be void here.

46
00:03:34,770 --> 00:03:38,970
Give name and this is going to be string name.

47
00:03:40,520 --> 00:03:42,680
And this is going to be my name.

48
00:03:42,680 --> 00:03:44,060
Equals name.

49
00:03:44,090 --> 00:03:45,990
So this is the, uh.

50
00:03:46,010 --> 00:03:47,090
This is the.

51
00:03:49,020 --> 00:03:51,180
Yeah, this is the function now.

52
00:03:51,630 --> 00:03:58,770
And we will also create a new function named getName, which is going to be of course, give a return

53
00:03:58,770 --> 00:04:02,740
a string since the name is itself is a string string.

54
00:04:03,060 --> 00:04:06,530
Get get name and this name.

55
00:04:06,770 --> 00:04:10,950
Name is going to just return string and will not take any parameters.

56
00:04:10,950 --> 00:04:12,360
Just return the string.

57
00:04:12,360 --> 00:04:14,880
So return my name.

58
00:04:14,880 --> 00:04:20,280
So we have the setter and getter here.

59
00:04:22,520 --> 00:04:32,510
So as we see in this course here, we cannot access the M variable directly since we access and we assigned

60
00:04:32,510 --> 00:04:35,290
it as private here.

61
00:04:35,300 --> 00:04:37,130
This is the private variable.

62
00:04:37,990 --> 00:04:44,050
So however, we have two public methods to access variables from the inside class.

63
00:04:44,050 --> 00:04:49,210
So the give name methods will modify the value here.

64
00:04:49,240 --> 00:04:52,390
The given modify will modify the.

65
00:04:53,020 --> 00:04:59,710
My name my name value and the get name get name.

66
00:04:59,710 --> 00:05:04,090
Here methods will return the my name value.

67
00:05:04,090 --> 00:05:13,360
So the here actually let's created some code snippet here and let's actually turn this and let's delete

68
00:05:13,360 --> 00:05:14,110
this now.

69
00:05:15,870 --> 00:05:18,990
And make it and also can delete the animal class here.

70
00:05:18,990 --> 00:05:25,860
And we will just create this animal class inside our the main CP here.

71
00:05:28,100 --> 00:05:29,490
And include.

72
00:05:29,510 --> 00:05:30,600
Include.

73
00:05:30,690 --> 00:05:31,730
String.

74
00:05:33,140 --> 00:05:35,120
And include.

75
00:05:35,960 --> 00:05:36,710
Include.

76
00:05:36,710 --> 00:05:37,130
Yeah.

77
00:05:37,370 --> 00:05:41,630
Stream is already included and using namespace STD.

78
00:05:43,910 --> 00:05:45,170
So here.

79
00:05:45,170 --> 00:05:48,520
Now let's actually try something in the main method here.

80
00:05:48,530 --> 00:05:52,570
So animal dog here, animal here.

81
00:05:52,580 --> 00:05:56,180
So as you know, the dog is animal here, dog here.

82
00:05:56,180 --> 00:05:58,400
We will give dog to the same.

83
00:05:59,240 --> 00:06:00,050
To name here.

84
00:06:00,050 --> 00:06:01,940
So give name.

85
00:06:02,330 --> 00:06:06,380
It's going to be let's actually name our dog Oxley.

86
00:06:06,670 --> 00:06:07,310
Yeah.

87
00:06:07,340 --> 00:06:08,930
Name our dog Oxley here.

88
00:06:08,930 --> 00:06:12,710
And we will print something C out high.

89
00:06:14,060 --> 00:06:14,750
I.

90
00:06:15,560 --> 00:06:17,410
I am at.

91
00:06:17,660 --> 00:06:18,890
I am here.

92
00:06:18,890 --> 00:06:25,310
We will use a dog dot, get name, get name and end line.

93
00:06:26,710 --> 00:06:30,400
So here, let's run our program here.

94
00:06:31,950 --> 00:06:33,090
It's close.

95
00:06:36,280 --> 00:06:41,600
A g++ main.cpp a dot exe.

96
00:06:42,520 --> 00:06:46,360
So here I am, a Oxley.

97
00:06:46,360 --> 00:06:48,630
So our dog name is Oxley here.

98
00:06:48,640 --> 00:06:54,100
So in this code we created a variable named dog of the type of animal.

99
00:06:54,100 --> 00:07:03,040
Since the dog has the ability that animal has, such as invoking the given name and get name methods

100
00:07:03,040 --> 00:07:03,670
here.

101
00:07:04,700 --> 00:07:07,850
This is the output you should get here.

102
00:07:07,910 --> 00:07:10,250
Hi my, I'm a auxiliar here.

103
00:07:10,280 --> 00:07:10,940
Hi.

104
00:07:10,940 --> 00:07:11,160
I'm.

105
00:07:11,180 --> 00:07:13,300
And let's actually change the dog name here.

106
00:07:13,310 --> 00:07:14,090
Hi.

107
00:07:14,290 --> 00:07:16,520
I'm a sea lion.

108
00:07:16,520 --> 00:07:19,640
Or I am CP dog.

109
00:07:19,880 --> 00:07:21,950
Yeah, that's acceptable.

110
00:07:21,950 --> 00:07:24,590
Here and here.

111
00:07:24,590 --> 00:07:27,440
And after that let's run a here.

112
00:07:27,440 --> 00:07:29,570
Hi, I'm a CP dog here.

113
00:07:30,430 --> 00:07:38,920
Now we can say that Animal ADT Abstract data type has two functions and they are give name.

114
00:07:40,070 --> 00:07:42,380
The given name.

115
00:07:43,410 --> 00:07:45,870
And the get name.

116
00:07:46,880 --> 00:07:53,570
So after talking about the Simple class, you might see that there's a similarity between struct and

117
00:07:53,570 --> 00:07:53,930
classes.

118
00:07:53,930 --> 00:07:56,780
So they both actually have similar behaviors.

119
00:07:56,780 --> 00:08:03,890
So the differences are however that struct have the default public members while classes have the default

120
00:08:03,890 --> 00:08:04,880
private members.

121
00:08:04,880 --> 00:08:11,960
So I personally recommend using struct as a data structures only so they don't have any methods in them

122
00:08:11,960 --> 00:08:15,140
and using classes to build abstract data types.

123
00:08:15,170 --> 00:08:18,770
ADTs So as you can see in this code here.

124
00:08:19,700 --> 00:08:25,920
The we assign the variable to the instance of the animal class by using its constructor.

125
00:08:25,940 --> 00:08:27,250
Here, this is he.

126
00:08:27,260 --> 00:08:29,420
This is animal class constructor here.

127
00:08:30,550 --> 00:08:35,000
So which is as you can see, this is the our animal class constructor.

128
00:08:35,020 --> 00:08:40,150
However, we can initialize a class data member by using a class constructor.

129
00:08:40,180 --> 00:08:46,630
The constructor name is the same as the class name, so let's refactor our receiving animal class so

130
00:08:46,630 --> 00:08:47,560
it has a constructor.

131
00:08:47,560 --> 00:08:49,480
So the refactored code here.

132
00:08:49,960 --> 00:08:55,190
Let's actually go to animal class here and let's actually refactor our class.

133
00:08:55,210 --> 00:08:57,340
Yeah, the animal class here.

134
00:08:57,370 --> 00:08:59,020
We're going to have the.

135
00:09:00,090 --> 00:09:01,590
Inside the public.

136
00:09:03,010 --> 00:09:03,730
We will also.

137
00:09:04,840 --> 00:09:05,860
Add some methods here.

138
00:09:05,860 --> 00:09:08,110
So in public we're going to animal here.

139
00:09:08,110 --> 00:09:09,340
This is the constructor.

140
00:09:09,550 --> 00:09:12,940
String name will get animal and.

141
00:09:13,850 --> 00:09:17,120
My name is going to be Name.

142
00:09:19,870 --> 00:09:22,270
And here, this is our constructor here.

143
00:09:23,290 --> 00:09:27,880
And here we don't need this our give name method here.

144
00:09:28,240 --> 00:09:30,250
Anyway, so let's get rid of them.

145
00:09:30,250 --> 00:09:31,240
And here we can.

146
00:09:31,240 --> 00:09:34,900
We will pass the Oxley here as our dog name.

147
00:09:35,290 --> 00:09:36,730
And here.

148
00:09:38,500 --> 00:09:41,230
It will work the same, but the less code.

149
00:09:44,930 --> 00:09:48,700
That's a dot x and x, as you can see here.

150
00:09:48,710 --> 00:09:50,200
I'm I'm actually.

151
00:09:50,390 --> 00:09:58,670
So as we can see in this code, we when we define the dog variable, we also initialize the my my name

152
00:09:58,670 --> 00:10:00,230
private variable of the class.

153
00:10:00,230 --> 00:10:06,710
So we don't need the get give name or we actually need the get name method for now, but we don't need

154
00:10:06,710 --> 00:10:09,710
the give name method anymore.

155
00:10:09,710 --> 00:10:11,450
So to assign the private variable.

156
00:10:11,450 --> 00:10:18,650
So indeed we will get same output again if I build and run presenting code as we did here.

157
00:10:18,650 --> 00:10:23,510
So in this code we assign dog as the animal type.

158
00:10:23,510 --> 00:10:27,530
So however we can also derive a new class based on the base class.

159
00:10:27,530 --> 00:10:34,820
So by deriving from the base class, the derived class will also have the behavior that the base class

160
00:10:34,820 --> 00:10:35,330
has.

161
00:10:35,330 --> 00:10:38,060
So let's refactor the animal class again.

162
00:10:38,060 --> 00:10:43,640
And in next lecture we will add virtual method named Makesound here.

163
00:10:43,640 --> 00:10:46,410
So I'm waiting you in next lecture.