1
00:00:01,320 --> 00:00:07,950
This video is geared towards teaching you about object oriented programming and more specifically classes

2
00:00:08,040 --> 00:00:11,280
objects methods and properties.

3
00:00:11,280 --> 00:00:16,980
I've already created the project and it is called classes and objects so you can pause here and go ahead

4
00:00:16,980 --> 00:00:22,150
and create this new project under your solution and resume when you are done.

5
00:00:22,140 --> 00:00:29,670
Now let's get started with what a class is and a class is a very very important keyword when talking

6
00:00:29,670 --> 00:00:32,920
about object oriented programming languages.

7
00:00:32,940 --> 00:00:38,960
I would have used that expression multiple times and so this is the explanation.

8
00:00:39,000 --> 00:00:42,920
Now our class is a blueprint for a data type right.

9
00:00:42,930 --> 00:00:50,960
So for a bit more context we have data types we have into a string with boolean we have char right.

10
00:00:50,970 --> 00:00:57,660
And so there are times when we probably need our own data type because we need to define something instead

11
00:00:57,660 --> 00:01:04,500
of for a program that has unique properties and maybe even a mixture of those other base data types

12
00:01:04,500 --> 00:01:05,780
that I just mention.

13
00:01:05,820 --> 00:01:13,260
And so our class allows us to define our own data type which can be a combination of these other types

14
00:01:13,350 --> 00:01:16,470
and properties and methods that we want.

15
00:01:16,980 --> 00:01:22,130
All right so that was a very unofficial explanation of it and I hope it made sense.

16
00:01:22,140 --> 00:01:29,760
But even if it is still unclear as to what it is where a bullet creates a class and I want to explain

17
00:01:29,760 --> 00:01:32,550
in detail everything as we go along.

18
00:01:32,940 --> 00:01:38,510
So let's just say we wanted our own class called box no note.

19
00:01:38,550 --> 00:01:39,780
We already have a class.

20
00:01:39,810 --> 00:01:45,210
We have the keyword class that tells us well this is a class and it's called program but I want another

21
00:01:45,210 --> 00:01:53,850
class that is not programmed so I can't define a class or well it is generally discouraged to find a

22
00:01:53,850 --> 00:01:55,680
class instead of one other class.

23
00:01:55,830 --> 00:01:58,680
But I do need it inside of the namespace.

24
00:01:58,680 --> 00:02:04,060
So instead of the curly braces for my namespace I'm just going to create another class.

25
00:02:04,080 --> 00:02:12,200
Just press enter twice and then I will see class and this class is going to be called Box.

26
00:02:12,210 --> 00:02:18,530
So I want a class called Box I want a data type that looks like a box.

27
00:02:18,550 --> 00:02:20,220
No I did say it's a blueprint.

28
00:02:20,310 --> 00:02:23,640
So when you're defining a class you need to see it yourself.

29
00:02:23,640 --> 00:02:28,200
Okay I've said any class I need a new data type.

30
00:02:28,230 --> 00:02:29,700
I've given it a name.

31
00:02:29,700 --> 00:02:31,470
What does it usually look like.

32
00:02:31,470 --> 00:02:33,260
What are the properties.

33
00:02:33,270 --> 00:02:39,930
And when I say properties they are the defining characteristics of this new data type.

34
00:02:39,930 --> 00:02:47,580
Well I can tell you that a box is a 3D object generally speaking and a box usually has Length Breadth

35
00:02:47,880 --> 00:02:48,880
and Height.

36
00:02:48,990 --> 00:02:49,340
Right.

37
00:02:49,350 --> 00:02:52,850
So we know three properties that this box will have.

38
00:02:52,860 --> 00:02:58,040
So did it find properties I will need the access modifier.

39
00:02:58,140 --> 00:03:02,150
So we looked at one in when we're doing methods I would call it static.

40
00:03:02,190 --> 00:03:05,070
Well there's another one you have well public.

41
00:03:05,070 --> 00:03:06,180
You also have private.

42
00:03:06,180 --> 00:03:10,960
So in the case of a class we can define it as public.

43
00:03:11,010 --> 00:03:17,640
Then we give it to data types so the data type can be of another class or it can be off base data type.

44
00:03:17,970 --> 00:03:21,210
So once again this is me defining identities.

45
00:03:21,220 --> 00:03:25,060
So if I add another class somewhere else I could use it as a data type.

46
00:03:25,120 --> 00:03:32,940
No however I'm keeping it simple so public and then my data type for a length would probably be something

47
00:03:32,940 --> 00:03:34,070
like double.

48
00:03:34,230 --> 00:03:36,150
And then I'm going to call it length.

49
00:03:36,750 --> 00:03:40,820
Then I'm just going to say get come on sit.

50
00:03:40,850 --> 00:03:41,250
All right.

51
00:03:41,460 --> 00:03:43,380
And that's pretty much what that looks like.

52
00:03:43,380 --> 00:03:47,310
So public double length.

53
00:03:47,370 --> 00:03:52,890
And then they get there and sets are meaning this is allowing me to retrieve the value.

54
00:03:52,890 --> 00:03:55,570
And this is allowing me to set a value.

55
00:03:55,620 --> 00:04:02,410
All right so I can get the value from my property call the length and I can set a value and as he visits

56
00:04:02,480 --> 00:04:07,580
it is kind of hinting at me that you know I'm violating the naming convention so let me see what they're

57
00:04:07,590 --> 00:04:08,550
going to tell me.

58
00:04:08,610 --> 00:04:14,820
And they're just suggesting that properties off classes should get capital letters All right.

59
00:04:15,090 --> 00:04:16,240
So let's try that again.

60
00:04:16,240 --> 00:04:21,300
No this I'm going to show you a keyboard shortcuts when defining properties instead of a class in C

61
00:04:21,300 --> 00:04:29,760
sharp and Visual Studio you can write the word prop and then w top tab and then it will kind of complete

62
00:04:29,760 --> 00:04:30,750
that line for you.

63
00:04:30,780 --> 00:04:34,070
So he's going to highlight the data type I can just press.

64
00:04:34,140 --> 00:04:39,750
All right w then press tab and then move on to the next one which is my property on this one I wanted

65
00:04:39,750 --> 00:04:45,080
to see Brett and I'm using the suggested naming convention this time.

66
00:04:45,120 --> 00:04:49,150
Then I press enter and then it adds it to the property.

67
00:04:49,150 --> 00:04:56,340
All right so I want to try that again prop w tab and then double and then tab and then this one is going

68
00:04:56,340 --> 00:05:01,180
to be height for us enter and we're done all right.

69
00:05:01,180 --> 00:05:09,100
And then congratulations you just defined your first user ID find it to type or your first class.

70
00:05:09,130 --> 00:05:11,880
Know that I have this user defined data type.

71
00:05:11,890 --> 00:05:13,180
What do I do with it.

72
00:05:13,170 --> 00:05:14,620
How do I use it.

73
00:05:14,620 --> 00:05:15,250
All right.

74
00:05:15,250 --> 00:05:21,130
So let us think about how we use regular data to sort of one the regular data type.

75
00:05:21,190 --> 00:05:27,700
We just specify our data type and then give it a name and then maybe give it some value right.

76
00:05:27,700 --> 00:05:32,250
So like when we wanted a number we would've said something like int.

77
00:05:32,440 --> 00:05:36,380
That's our data type or name and then give it a value.

78
00:05:36,490 --> 00:05:37,190
True.

79
00:05:37,310 --> 00:05:46,180
No we want to define box as a variable or want a variable of type box so box is a data type.

80
00:05:46,180 --> 00:05:46,720
No.

81
00:05:46,810 --> 00:05:50,110
And we want a variable that represents a box.

82
00:05:50,110 --> 00:05:55,440
So in order to initialize a new variable or what we'd call an object.

83
00:05:55,660 --> 00:05:58,820
So I'm just going to write a comment here.

84
00:05:58,930 --> 00:06:01,210
Create object of class type.

85
00:06:01,210 --> 00:06:03,670
Box then I'm going to say something like.

86
00:06:03,670 --> 00:06:04,570
BOX.

87
00:06:04,570 --> 00:06:09,220
SO I'M JUST GOING TO CALL IT THE SAME WAY WE CALLED IT IS A C and where I'm just calling in the data

88
00:06:09,220 --> 00:06:13,060
type and then I'm going to give you 10 name someone to give it.

89
00:06:13,060 --> 00:06:19,840
Come on B box so it's very case sensitive if I define the class with I can meet with a capital B then

90
00:06:19,900 --> 00:06:22,060
it's going to be seen differently.

91
00:06:22,090 --> 00:06:28,570
Come on B but it could have been anything I could have said Box B box to be one the same naming convention

92
00:06:28,800 --> 00:06:32,960
that we would have used to go for and how we need more variables would apply.

93
00:06:32,970 --> 00:06:38,860
Here are the only exception is that they can do the case really matters a lot.

94
00:06:39,010 --> 00:06:41,420
So I have my data type box.

95
00:06:41,470 --> 00:06:44,370
I notice that it's got a color coded just like program.

96
00:06:44,380 --> 00:06:47,530
So that's a class and then box is color coded.

97
00:06:47,530 --> 00:06:54,130
Come on B box is color coded just like gnome so that's my variable are in this situation my object and

98
00:06:54,130 --> 00:07:01,450
that I'm going to initialize it to a new instance of box and this step is very important.

99
00:07:01,450 --> 00:07:08,110
All right so with all this step then well it would be it wouldn't work essentially.

100
00:07:08,140 --> 00:07:14,830
So if I just said Box B and semicolon visual studio would kind of accept it but then nothing that we

101
00:07:14,830 --> 00:07:18,310
do afterwards would work it would just throw arrows all right.

102
00:07:18,310 --> 00:07:25,560
So every time you're using a new class or a new user defined object.

103
00:07:25,660 --> 00:07:26,050
Sorry.

104
00:07:26,050 --> 00:07:33,050
A new user defined data type which is in the form of a class that you would have created.

105
00:07:33,220 --> 00:07:40,570
Then you need to initialize it by saying that class name some object name is equal to a new instance

106
00:07:40,660 --> 00:07:45,910
off that class name again and open and close braces.

107
00:07:45,910 --> 00:07:50,560
There are times you may see contents in the braces but this is not one of those times so I'm not going

108
00:07:50,560 --> 00:07:57,220
to bring up that scenario just yet and we'll just press ahead with our objective.

109
00:07:57,610 --> 00:08:02,810
So no that we have our box object or our box variable.

110
00:08:02,850 --> 00:08:05,880
Know I'm going to start calling it object from no on right.

111
00:08:05,920 --> 00:08:11,670
I keep on calling it variable sake and can run them into parallel but it's really an object wants itself

112
00:08:11,680 --> 00:08:16,040
a class type and it's no initialized it's no one object.

113
00:08:16,070 --> 00:08:23,980
All right so I can see a box and then a very very special operator that I know you've seen quite a few

114
00:08:23,980 --> 00:08:27,130
times and it probably just never will mean much to you.

115
00:08:27,130 --> 00:08:32,890
We have our full stop so box dot and then look at what the intelligence is doing.

116
00:08:32,890 --> 00:08:39,130
It's telling me that I have access to a property you see that range that range means property called

117
00:08:39,180 --> 00:08:45,910
breadth I have access to a property called height a property called length of three off which I just

118
00:08:45,910 --> 00:08:48,250
defined inside of my class.

119
00:08:48,250 --> 00:08:48,670
All right.

120
00:08:48,910 --> 00:08:52,170
So they're telling me that I can get and I can set.

121
00:08:52,180 --> 00:08:59,440
Which means that I can print box that length if I need to and I can also see a box that length is equal

122
00:08:59,440 --> 00:09:00,730
to some value.

123
00:09:00,730 --> 00:09:03,850
Someone to do that somewhere to set some values or box that length.

124
00:09:03,870 --> 00:09:16,760
So box that length is 10 and then I'm going to say box dot width or sorry breadth is equal to 15 and

125
00:09:16,760 --> 00:09:22,400
then I'm also going to say a box dot height is equal to 5.

126
00:09:22,430 --> 00:09:24,490
So I'm setting values here.

127
00:09:24,530 --> 00:09:31,320
So C sharp makes it very easy for you to create an object and then set values for these objects.

128
00:09:31,340 --> 00:09:37,780
So when I'm putting or assigning values that is me sitting when I am printing.

129
00:09:37,780 --> 00:09:43,730
That is me getting so I can actually do a console dot right line.

130
00:09:43,850 --> 00:09:45,910
All right so you see that dot operator again.

131
00:09:45,920 --> 00:09:52,520
And notice the color coding on the word console it looks just like the color coding on box and on program

132
00:09:52,790 --> 00:09:55,460
and every other class that we would call it.

133
00:09:55,490 --> 00:10:03,060
So that means the creators of the language see sharp created a class and then this class.

134
00:10:03,490 --> 00:10:08,000
And I know this because after the dot upper until the sensation of everything that I can look at in

135
00:10:08,000 --> 00:10:13,040
the class it has many properties and methods so the cube represents a method right.

136
00:10:13,310 --> 00:10:15,330
So I have a method called right.

137
00:10:15,410 --> 00:10:20,990
I also have a property called Oh it's a property called era property called this a property called that.

138
00:10:21,080 --> 00:10:22,820
My class only has three properties.

139
00:10:22,820 --> 00:10:29,480
This one has so many other properties that I may may never use in all honesty I have never used some

140
00:10:29,480 --> 00:10:34,970
of these things in here but the tools are there so I'm just trying to show you that when you're creating

141
00:10:34,970 --> 00:10:36,410
a class it is up to you.

142
00:10:36,410 --> 00:10:42,170
This is a blueprint but then it gets initialized and then everything becomes real because they can actually

143
00:10:42,470 --> 00:10:48,880
interact with the properties and methods you would have defined someone to say a console.

144
00:10:48,890 --> 00:10:49,960
That's right.

145
00:10:49,960 --> 00:10:58,420
Line and then I would just want to print out box dimensions are box length box thought breadth and box

146
00:10:58,420 --> 00:10:59,210
dot height.

147
00:10:59,210 --> 00:11:00,940
Right so I'm just printing about the volume.

148
00:11:00,950 --> 00:11:06,890
So like I said when you are trying to view the values you're really doing I get but when you're assigning

149
00:11:06,890 --> 00:11:13,190
the values you're doing I sit and look out what happens if I remove the set from length and I remove

150
00:11:13,190 --> 00:11:15,580
the get from height.

151
00:11:15,580 --> 00:11:15,980
All right.

152
00:11:16,280 --> 00:11:24,460
So now I have an arrow because I'm trying to set a value on a property that only allows me to get right.

153
00:11:24,470 --> 00:11:30,240
Yes it's public but it's seeing that you're not allowed to place a value inside this property.

154
00:11:30,250 --> 00:11:35,600
And then it's giving me that arrow because it's saying oh that's illegal it's read only you can only

155
00:11:35,780 --> 00:11:37,010
retrieve the value.

156
00:11:37,040 --> 00:11:41,140
So it's not giving me an error when I'm printing it because I'm only retrieving here.

157
00:11:41,210 --> 00:11:41,790
All right.

158
00:11:41,840 --> 00:11:44,990
And then just the same way for the the height.

159
00:11:44,990 --> 00:11:46,190
I only put it to set.

160
00:11:46,190 --> 00:11:50,540
So yes I can put a value there but I cannot retrieve it.

161
00:11:50,690 --> 00:11:51,200
All right.

162
00:11:51,200 --> 00:11:56,000
So I'm just pointing that out too because when you're going to be interacting with other classes.

163
00:11:56,110 --> 00:12:03,020
Well one when you're defining your own classes you're going to be very careful if you know if necessary

164
00:12:03,380 --> 00:12:07,460
to know what level of access you're giving to what property.

165
00:12:07,550 --> 00:12:11,390
So human being probably is.

166
00:12:11,390 --> 00:12:16,170
Well let's say you would meet any human being unless you give birth to this human being.

167
00:12:16,190 --> 00:12:19,220
You would have met them with a name so you don't just go ahead and sit.

168
00:12:19,220 --> 00:12:24,510
Name you don't set first name on set last name but you can get that information right.

169
00:12:24,530 --> 00:12:30,770
So if you were ever to define a class that maybe you call a person that looks like a human being you

170
00:12:30,770 --> 00:12:36,590
know you're defining with properties of a human being on a property of a human being would be a first

171
00:12:36,590 --> 00:12:38,750
name another property would be a last name.

172
00:12:38,750 --> 00:12:39,320
Right.

173
00:12:39,380 --> 00:12:45,340
You probably would have a first name with only get and last name we only get.

174
00:12:45,340 --> 00:12:45,650
All right.

175
00:12:45,680 --> 00:12:52,760
But then you probably have something is that can get full name and you would never probably sit sit

176
00:12:53,060 --> 00:12:57,200
put saris put us sit on the first name on the last name.

177
00:12:57,200 --> 00:13:02,750
All right so I put about my sister and might get her on my my property is in my class and I'm going

178
00:13:02,750 --> 00:13:10,810
to execute this program so let me just quickly switch over they start a program all right so a very

179
00:13:10,810 --> 00:13:16,160
simple program does spring to the box them Injuns are 10 15 and 5.

180
00:13:16,180 --> 00:13:22,180
Just like all we define them 10 15 5 and then we printed out our sentence.

181
00:13:22,210 --> 00:13:28,810
So we've been doing a lot of input output programs so you could actually modify this to receive the

182
00:13:28,810 --> 00:13:33,210
three numbers as inputs and then set the values and then do the print.

183
00:13:33,220 --> 00:13:34,200
So I'm going to do it.

184
00:13:34,210 --> 00:13:36,220
I want you to pause this video right.

185
00:13:36,220 --> 00:13:37,630
No and attempt to do yourself.

186
00:13:37,930 --> 00:13:40,920
And then you on pause and then we go through it together.

187
00:13:40,930 --> 00:13:43,420
All right so I've completed that exercise.

188
00:13:43,570 --> 00:13:46,800
So I put it in some comments and kind of rearrange the code.

189
00:13:46,900 --> 00:13:51,490
So it's always nice to have your declarations kind of one place.

190
00:13:51,570 --> 00:13:56,140
I mean I do accept that sometimes you don't know what variables you need until you get to the point

191
00:13:56,170 --> 00:14:03,430
but when you can just try and put all of them in one area and then I prompted for the three numbers

192
00:14:03,460 --> 00:14:07,530
and then I set them and then I got them.

193
00:14:07,570 --> 00:14:08,060
All right.

194
00:14:08,080 --> 00:14:11,980
So let's just run that and see how that works.

195
00:14:11,980 --> 00:14:17,460
So I'm getting the length and this is going to be a box that's 10 by 15 by a 5.

196
00:14:17,620 --> 00:14:18,760
And then it's just into print.

197
00:14:18,760 --> 00:14:21,920
The dimensions are 10 by 15 but by 5.

198
00:14:21,980 --> 00:14:22,700
No.

199
00:14:22,810 --> 00:14:25,630
What if I wanted to do something with those values.

200
00:14:25,630 --> 00:14:32,320
What if my I wanted my box to tell me its volume so I know it's length.

201
00:14:32,410 --> 00:14:33,380
I know it's breadth.

202
00:14:33,550 --> 00:14:41,620
I know it's height but then I wanted to calculate the volume based on the properties know what I can

203
00:14:41,620 --> 00:14:47,100
do is define a method so I can define a function inside of my class.

204
00:14:47,110 --> 00:14:53,080
And just for context notice we have the class called program and it has a function.

205
00:14:53,140 --> 00:14:58,540
So we went through all hold to define functions and I'm just going to use the same principles except

206
00:14:58,750 --> 00:15:02,500
this time I'm inside of a class a new class body.

207
00:15:02,500 --> 00:15:02,830
Right.

208
00:15:02,830 --> 00:15:08,320
So the losses of functions we defined them instead of the class program but I don't want these methods

209
00:15:08,320 --> 00:15:15,310
inside of program I want them inside of my class called the box and this method is going to return the

210
00:15:15,310 --> 00:15:15,730
volume.

211
00:15:15,730 --> 00:15:17,880
So I'm want to call it get volume.

212
00:15:18,020 --> 00:15:18,330
All right.

213
00:15:18,510 --> 00:15:25,720
So I want to say public and then I wanted to return a value server meal and its value returning we have

214
00:15:25,720 --> 00:15:27,720
to specify a data type.

215
00:15:27,730 --> 00:15:37,050
Some would you say double and then I'm want to call it get volume and then it is not taking any parameters.

216
00:15:37,070 --> 00:15:43,600
Now explain why it's not taking parameters it doesn't need to take parameters because it is a part of

217
00:15:43,600 --> 00:15:49,170
the class that has the properties so as as our results they're all like siblings.

218
00:15:49,180 --> 00:15:52,060
The properties are siblings than normal each other.

219
00:15:52,060 --> 00:15:57,850
The methods are siblings with the properties so you can actually just reference them directly inside

220
00:15:57,850 --> 00:15:58,750
of the method.

221
00:15:58,750 --> 00:16:03,820
You don't have to pass in any parameters because they're all inside of that box.

222
00:16:03,820 --> 00:16:07,710
All right so I mean like I said this is a data type definition.

223
00:16:07,720 --> 00:16:15,010
So if I have a box that says a length with a height it's also as I value all of those are still related

224
00:16:15,010 --> 00:16:16,590
to this one box.

225
00:16:16,660 --> 00:16:22,090
So you can think of a ladder you define the class you gave it properties maybe you gave it a method

226
00:16:22,330 --> 00:16:29,080
or two functions whatever it is but they are all a part of any one object of this box.

227
00:16:29,080 --> 00:16:29,350
All right.

228
00:16:29,590 --> 00:16:35,700
So I'm going to say and then notice the red line because its value returned so I need to return.

229
00:16:36,070 --> 00:16:43,470
And then I'm returning length times red times height.

230
00:16:43,570 --> 00:16:49,120
All right so that's so we get the volume of any 3D objects.

231
00:16:49,600 --> 00:16:59,260
So no that I have this value I can go back to my main phone Sean or let me put it in the area where

232
00:16:59,260 --> 00:17:06,190
I'm getting the properties and then I'm just going to see it volume so I did say it's good to declare

233
00:17:06,190 --> 00:17:12,930
variables in one area on this you you realize you needed somewhere else say it as they cleared so into

234
00:17:12,940 --> 00:17:19,750
volume is going to be equal to our object call box when I said Dot you're going to notice that I have

235
00:17:19,750 --> 00:17:22,630
get volume no available to me.

236
00:17:22,630 --> 00:17:26,380
So when I say get volume it will meet that function call.

237
00:17:26,410 --> 00:17:34,000
So when it's executing it gets the values from our users and then it sets the values and then we get

238
00:17:34,000 --> 00:17:41,470
the volume but then notice of an error here because it's and I am returning a double but I'm storing

239
00:17:41,470 --> 00:17:49,990
it inside of an int so bad that needs to be double volume is equal to get volume and then what I'm going

240
00:17:49,990 --> 00:18:01,260
to do is say box volume is and then I'm just printing back the value that is inside of my variable called

241
00:18:01,650 --> 00:18:02,950
volume.

242
00:18:02,970 --> 00:18:06,040
All right so let's go through this again.

243
00:18:06,050 --> 00:18:09,890
We have a box we declared a data object called box.

244
00:18:10,010 --> 00:18:16,630
We're filling it with values and then we're calculating a volume based on those values no look I'll

245
00:18:16,640 --> 00:18:22,550
need this code looks imagine if you were to write all of those things one place and it can get messy

246
00:18:22,550 --> 00:18:31,790
so inside of your class you can have as many functions I could even see public maybe I have another

247
00:18:31,790 --> 00:18:41,150
function that gets the area so I'm going to say get area this time of any one side and then area is

248
00:18:41,150 --> 00:18:44,920
usually length by breadth so it's not the heights right.

249
00:18:44,960 --> 00:18:55,350
So I have another function so I can do another one where I see double area is equal to box dot get area.

250
00:18:55,460 --> 00:19:03,540
So as many functions as I will need or want I can define them inside of my class and then on on you

251
00:19:03,540 --> 00:19:12,110
know on a need need by need basis I just declare my object made my function call and then get the value

252
00:19:12,440 --> 00:19:14,460
and you can have void functions also.

253
00:19:14,460 --> 00:19:20,940
So it's not always value returns I'm just going to duplicate this line using control D and print out

254
00:19:20,990 --> 00:19:27,320
the area that's I'm getting back all right so let's try and run this program and I'm going to do something

255
00:19:27,320 --> 00:19:33,910
that I know is going to throw an arrow noticed that I carelessly have been using double.

256
00:19:34,010 --> 00:19:38,880
So I'm in suggesting that my length breadth and height can be double.

257
00:19:38,900 --> 00:19:42,680
However I am only doing an inch that pass to the Reid line.

258
00:19:42,710 --> 00:19:44,060
So this is the arrow.

259
00:19:44,180 --> 00:19:53,000
If my length was one point five and I press enter then I'm getting an on handled exception error.

260
00:19:53,000 --> 00:19:53,350
All right.

261
00:19:53,360 --> 00:19:58,670
So we did talk about the exception handling where it's good to wrap it up in the try catch to avoid

262
00:19:58,670 --> 00:19:59,680
these kinds of errors.

263
00:19:59,930 --> 00:20:05,360
But just for simplicity's sake I'm just going to choose this I'll say if we have inquires fires then

264
00:20:05,360 --> 00:20:06,840
guess what we also have.

265
00:20:06,920 --> 00:20:15,430
We have double dot pass art and if we're doing a double dot pass we also need to have the value that

266
00:20:15,430 --> 00:20:17,110
is being passed going into a double.

267
00:20:17,410 --> 00:20:17,740
All right.

268
00:20:17,740 --> 00:20:19,840
So let's just changes all to doubles.

269
00:20:19,900 --> 00:20:21,720
Like I said is very strict.

270
00:20:21,880 --> 00:20:24,270
And then we just change them all to double.

271
00:20:24,280 --> 00:20:29,630
So we have double anyone doing a double pass and double double double double double.

272
00:20:29,680 --> 00:20:33,200
And everything is no relative to doubles.

273
00:20:33,250 --> 00:20:43,490
So let's try this again so the length is one point five and the breadth is three point four and the

274
00:20:43,640 --> 00:20:45,000
height is nine.

275
00:20:45,050 --> 00:20:46,930
Just some random dimensions.

276
00:20:46,940 --> 00:20:53,780
So now I'm seeing that the dimensions are those three values the area are the volume sorry is forty

277
00:20:53,780 --> 00:20:54,860
five point nine.

278
00:20:54,860 --> 00:20:57,810
So that's one point five times three point four times nine.

279
00:20:57,980 --> 00:21:04,490
And then the area is five point one because that's one point five times three point four.

280
00:21:04,490 --> 00:21:09,110
So now we have some data tab that represents a box.

281
00:21:09,260 --> 00:21:09,950
Well guess what.

282
00:21:09,950 --> 00:21:14,750
What if we had two boxes or more than one boxes or we had a collection of boxes.

283
00:21:14,750 --> 00:21:18,890
The fact is that we can define as many boxes as we need.

284
00:21:18,890 --> 00:21:21,220
So I'm going to say this is box.

285
00:21:21,410 --> 00:21:28,150
And then there's a second box that I need to be aware of for work or dimension as far as I can see.

286
00:21:28,160 --> 00:21:30,730
Box do.

287
00:21:31,250 --> 00:21:32,480
So there is nothing stopping me.

288
00:21:32,660 --> 00:21:37,890
It's just that all we can have multiple integer variables multiple string variables.

289
00:21:37,940 --> 00:21:43,320
You can have multiple objects and misspellings defeating me.

290
00:21:43,370 --> 00:21:46,120
You can have multiple objects of the same data type.

291
00:21:46,130 --> 00:21:48,510
As long as the names are not the same.

292
00:21:48,550 --> 00:21:49,140
Right.

293
00:21:49,190 --> 00:21:53,580
So I can have box box to box five box ten.

294
00:21:53,600 --> 00:21:53,930
No.

295
00:21:53,930 --> 00:21:59,470
Imagine trying to fill in the dimensions of a warehouse full of boxes.

296
00:21:59,570 --> 00:22:04,700
So you know that there are 10 boxes and you have to write a program to allow them to enter the dimensions

297
00:22:04,700 --> 00:22:05,540
for 10 boxes.

298
00:22:05,540 --> 00:22:12,590
Then you're going to have box box to box three box for a box five and then you went off problems per

299
00:22:12,590 --> 00:22:19,280
box because then for Box 2 and went to have to repeat all of these steps just to make sure that I'm

300
00:22:19,280 --> 00:22:20,990
getting 4 box 2.

301
00:22:21,140 --> 00:22:22,660
So there is an easier way.

302
00:22:22,670 --> 00:22:30,740
I'm just giving an idea of how tedious it might get but I am just saying that that is what at this point

303
00:22:30,740 --> 00:22:32,020
we would have to do.

304
00:22:32,050 --> 00:22:34,430
So I'm just going to proceed with Box 2.

305
00:22:34,430 --> 00:22:42,250
So we have the promise for the vies for the box dimensions and we're sitting and printing the values

306
00:22:42,260 --> 00:22:45,260
already sitting and calculating the values for our box.

307
00:22:45,290 --> 00:22:53,280
So I'm just going to duplicate all of this and I'm going to do it again underneath.

308
00:22:53,460 --> 00:22:57,170
Right but then this time I'm going to change these zones.

309
00:22:57,170 --> 00:23:03,470
I'm not going to read it clear in 1 and 2 and 3 so like I said if you have to reuse a variable you can

310
00:23:03,470 --> 00:23:06,920
actually just forensic by name after it has been declared right.

311
00:23:06,920 --> 00:23:08,090
So we declared it here.

312
00:23:08,180 --> 00:23:09,370
We're not declaring target.

313
00:23:09,380 --> 00:23:10,520
We're just using it again.

314
00:23:10,520 --> 00:23:16,540
So I'm just making reference to it and then I'm changing these old to box one.

315
00:23:16,550 --> 00:23:19,900
So it's is it Box 1 box 2 Sorry.

316
00:23:19,940 --> 00:23:26,840
So we're changing these references out to Box 2 and then once I'm done this I'll just explain quickly

317
00:23:26,840 --> 00:23:39,680
exactly what is happening here and then I'm going to duplicate all these print lines we're all right.

318
00:23:41,680 --> 00:23:50,240
Where I'm going to be printing bucks to dimensions and then notes I'm going to have to overwrite.

319
00:23:50,270 --> 00:23:55,070
So I'm not going to do an override what I'm going to show you that you can actually print directly from

320
00:23:55,130 --> 00:23:55,880
our return.

321
00:23:55,880 --> 00:23:56,640
Right.

322
00:23:56,690 --> 00:24:03,830
So open to know what I've suggested that you put the return value sermon but I get volume is a function

323
00:24:04,190 --> 00:24:08,150
that returns something so in it returns that value.

324
00:24:08,240 --> 00:24:14,180
I notice I didn't use a variable this time I just returned the result of this calculation and in that

325
00:24:14,180 --> 00:24:20,060
result of the calculation is going to get stored inside volume no don't hear I'm printing volume and

326
00:24:20,060 --> 00:24:26,900
I'm printing era which we know are for box the first box I went to remove those declarations for the

327
00:24:26,900 --> 00:24:35,840
second box so all I'm sitting is the height the breadth and the length but then I'm printing box to

328
00:24:35,960 --> 00:24:43,300
dots and then I'm just going to call a function right there get volume and then I'm going to print again.

329
00:24:43,430 --> 00:24:45,170
Box dots.

330
00:24:45,290 --> 00:24:45,610
Sorry.

331
00:24:45,620 --> 00:24:51,360
Box 2 dot get area.

332
00:24:51,370 --> 00:24:52,100
All right.

333
00:24:52,150 --> 00:24:59,060
So then I'm just showing you that you can print the variable you can do the return call get it storage

334
00:24:59,080 --> 00:25:04,560
in a variable and then manipulate the variable which might be more desirable if you have you know all

335
00:25:04,600 --> 00:25:10,450
the things you need to do with the value but then you can also just return it and have it print directly

336
00:25:10,450 --> 00:25:13,980
inside off your print operation.

337
00:25:13,990 --> 00:25:14,750
Right.

338
00:25:14,800 --> 00:25:16,200
So you have those two.

339
00:25:16,240 --> 00:25:19,360
And of course you have to know when you're using which method.

340
00:25:19,390 --> 00:25:24,260
So let's run this program once again where have two boxes.

341
00:25:24,280 --> 00:25:29,920
So have two boxes of of the data type that I just created called box.

342
00:25:30,020 --> 00:25:37,810
I'm going to print prompts to enter values for the first box and then I'm going to calculate the volume

343
00:25:37,810 --> 00:25:42,880
and the area that I want to prompt again to enter values for the second book.

344
00:25:42,880 --> 00:25:49,750
So I mean I can modify the prompt to say four box 1.

345
00:25:49,820 --> 00:25:57,270
All right so I'll just do that and then repeat that for the problems for Box 2 and then after getting

346
00:25:57,270 --> 00:26:03,300
the virus for Box 2 we're just sitting the dimensions accordingly and then we're just going to print

347
00:26:03,540 --> 00:26:12,290
box one dimension box one area box one volume and then box two box two and box.

348
00:26:12,370 --> 00:26:17,070
So I'm just adding these so that we have some visual cues as to which values our full box one and which

349
00:26:17,070 --> 00:26:18,270
one is our full box.

350
00:26:18,300 --> 00:26:22,980
So let's run this and see how that works.

351
00:26:22,990 --> 00:26:28,950
All right so I've already entered some of the values 5 6 and 3 4 dimensions for box 1 and then I want

352
00:26:28,950 --> 00:26:36,780
to see if 5 4 and 10 4 dimensions will box to press enter and then we can see here Box 1 dimensions

353
00:26:36,780 --> 00:26:44,280
are these 3 and then Box 2 dimensions are those 3 and those are the calculations issue that I'm still

354
00:26:44,280 --> 00:26:50,340
getting the area and the volume even though I'm just printing directly into the console or at line the

355
00:26:50,400 --> 00:26:51,720
return value.

356
00:26:51,720 --> 00:26:52,080
All right.

357
00:26:52,110 --> 00:26:59,280
So make sure don't get confused by the curly brace and that that we're making a function call instead

358
00:26:59,280 --> 00:27:00,960
of one sold out right line here.

359
00:27:00,990 --> 00:27:07,020
So when it gets to this line and it starts writing the text you realize is that all I have to make a

360
00:27:07,020 --> 00:27:07,970
function call.

361
00:27:08,190 --> 00:27:14,880
Let me go to the function and then that's going to return some value and then whatever it returns is

362
00:27:14,880 --> 00:27:23,040
what gets concatenated into the string that is being written to the console so like I keep on saying

363
00:27:23,040 --> 00:27:24,700
there are many ways to do things.

364
00:27:24,720 --> 00:27:31,500
I think that you know getting it back answering it in a variable is much cleaner much more much easier

365
00:27:31,500 --> 00:27:34,420
to read than something looking like this.

366
00:27:34,420 --> 00:27:40,820
But once again you have that method available to you know as a final item when to display it to you.

367
00:27:40,890 --> 00:27:43,050
The best way to handle your classes.

368
00:27:43,080 --> 00:27:51,210
So you would have had to go through the painstaking explanation of of seeing why we should not define

369
00:27:51,270 --> 00:27:53,310
another class instead of this class.

370
00:27:53,340 --> 00:27:53,610
Right.

371
00:27:53,640 --> 00:27:59,730
So we have class program and to go through you know quite a bit of record restructuring to make sure

372
00:27:59,730 --> 00:28:01,240
that I was not inside.

373
00:28:01,250 --> 00:28:04,500
It's fairly obvious what's inside of the namespace brace.

374
00:28:04,680 --> 00:28:13,200
And it is actually best practice it leads to much cleaner looking project files when I go to court and

375
00:28:13,200 --> 00:28:21,420
just court in general when you create a new file per class file so notice that we have a class called

376
00:28:21,420 --> 00:28:22,270
program.

377
00:28:22,320 --> 00:28:26,040
We have a corresponding file in our project called program.

378
00:28:26,090 --> 00:28:26,720
Yes.

379
00:28:26,790 --> 00:28:33,090
Which then means any class that you create it is best practice to create a new file.

380
00:28:33,090 --> 00:28:39,780
Call it that class name dot see s and please your definition of a class inside that file.

381
00:28:40,020 --> 00:28:41,700
So I'm actually going to do that right.

382
00:28:41,700 --> 00:28:47,010
No someone to take this class that we just created and I'm going to cut it.

383
00:28:47,040 --> 00:28:52,740
So all of the code associated with the class I'm just going to do control X and I'm cutting it from

384
00:28:52,740 --> 00:28:53,660
inside me.

385
00:28:53,880 --> 00:28:58,080
And then we if we give visual studio a few seconds and everything is going to go haywire it's going

386
00:28:58,080 --> 00:29:03,340
to be low definition for a bit the type period that doesn't exist.

387
00:29:04,380 --> 00:29:08,100
And then we're going to see a visual studio it's fine we know what we're doing so we're going to go

388
00:29:08,100 --> 00:29:14,230
over to our project classes on objects right click and then click add.

389
00:29:15,030 --> 00:29:19,170
And then what we're doing is adding a new class you see that class.

390
00:29:19,330 --> 00:29:20,870
So we click us.

391
00:29:20,970 --> 00:29:26,870
And then once again whatever the name of the class is it is best practice to give the file that name

392
00:29:26,870 --> 00:29:29,760
someone to call this glass box.

393
00:29:29,860 --> 00:29:36,880
So then it's going to go ahead and create a new file and it's going to even go as far as filling in

394
00:29:36,880 --> 00:29:42,040
the name of the class the box because contextually it's already naming the class.

395
00:29:42,070 --> 00:29:48,490
So I'm just going to replace this predefined code and notice it seeing for references and that's because

396
00:29:49,240 --> 00:29:56,980
just by me creating that class and box not properties are anything in my mean it automatically takes

397
00:29:56,980 --> 00:30:03,280
that in the data type is box so I know what I'm doing but then it has no properties it has no function.

398
00:30:03,280 --> 00:30:05,260
So everything is still haywire.

399
00:30:05,350 --> 00:30:11,020
So I'm just going to replace this block of code with the class that I just created.

400
00:30:11,020 --> 00:30:16,000
And then when I go back over to my main then everything is fine.

401
00:30:16,000 --> 00:30:22,600
So once again when we're able to create the class is actually better to just go to our project right

402
00:30:22,600 --> 00:30:30,920
click go to add click class your class name so let's say I created a class called Person.

403
00:30:30,940 --> 00:30:31,350
All right.

404
00:30:31,360 --> 00:30:35,530
And then do all of our definitions all of our properties.

405
00:30:35,530 --> 00:30:40,390
And I just filled the three properties quickly I didn't want to bore you with writing them so you can

406
00:30:40,390 --> 00:30:44,980
pause and write them off if you need to but their first name last name and age.

407
00:30:44,980 --> 00:30:51,730
And then I'm going to declare another one and this time I'm using a different access modifier and this

408
00:30:51,730 --> 00:30:54,010
one is going to be called private.

409
00:30:54,010 --> 00:30:58,450
So private would be celery for argument's sake.

410
00:30:58,490 --> 00:31:02,370
So stubble and SA right.

411
00:31:02,410 --> 00:31:03,020
All right.

412
00:31:03,350 --> 00:31:09,270
So I'm defining these as public and these as private.

413
00:31:09,280 --> 00:31:15,400
Know when something is private it means that nothing outside of the class can access it you cannot directly

414
00:31:15,400 --> 00:31:18,730
access this property from the object.

415
00:31:18,730 --> 00:31:19,060
All right.

416
00:31:19,060 --> 00:31:21,280
So let me just put that into context for it.

417
00:31:21,280 --> 00:31:22,980
So I want to go back to program.

418
00:31:23,020 --> 00:31:28,440
I'm not going to do too many modifications because person is coming on the tail end of this lesson.

419
00:31:28,570 --> 00:31:35,620
But let's just see what happens someone to say a person I notice it takes person because it's in a class

420
00:31:35,620 --> 00:31:40,240
file it's in the same namespace so they know about each other and their siblings.

421
00:31:40,240 --> 00:31:48,550
So person and then as usual I have to declare a new object off person someone to say capital P person

422
00:31:48,560 --> 00:31:50,080
that's the name of the class.

423
00:31:50,110 --> 00:31:56,290
Come on peepers and that's the name of the object is equal to a new instance of the person.

424
00:31:56,290 --> 00:31:56,670
All right.

425
00:31:57,100 --> 00:32:05,140
So I can say a person the object and say dot and then in tennis consistently me exactly what I can access

426
00:32:05,170 --> 00:32:10,810
I can access the age because that was public I can access the first name and last name because those

427
00:32:10,810 --> 00:32:12,100
two are also public.

428
00:32:12,190 --> 00:32:16,180
But I cannot access the salary because it is private.

429
00:32:16,180 --> 00:32:16,540
Right.

430
00:32:16,780 --> 00:32:23,860
So if I go as far as writing salary because I'm defying visas through the N C sharp I I'm going to say

431
00:32:23,860 --> 00:32:24,730
right.

432
00:32:24,820 --> 00:32:32,560
And I want to see salary then is going to say that it cannot it is not accessible because of its protection

433
00:32:32,560 --> 00:32:33,050
level.

434
00:32:33,050 --> 00:32:34,540
So because I said it's private.

435
00:32:34,540 --> 00:32:36,130
That's private information.

436
00:32:36,130 --> 00:32:39,830
I can just go on and say I want to see salary.

437
00:32:39,850 --> 00:32:40,150
All right.

438
00:32:40,150 --> 00:32:51,820
So usually when you have private properties or a private member feels inside of a class then you mean

439
00:32:51,880 --> 00:32:54,040
what you call get their function.

440
00:32:54,040 --> 00:32:58,480
So where are already defined that we can have a default get a default set.

441
00:32:58,480 --> 00:33:02,750
Once we define our public property.

442
00:33:02,800 --> 00:33:06,520
But then when it's private you probably don't want to do it like that.

443
00:33:06,520 --> 00:33:10,410
So you can't actually do something like defining a function.

444
00:33:10,420 --> 00:33:20,810
I'm just going to call this public and call it double and then when to say get salary and then this

445
00:33:21,410 --> 00:33:31,820
public function that I should be able to access when I say person dot will return salary so return salary.

446
00:33:31,810 --> 00:33:32,780
All right.

447
00:33:32,930 --> 00:33:36,550
And then what if I needed to set the value for a salary.

448
00:33:36,560 --> 00:33:42,860
Remember it's private and it doesn't have any getter and setter so usually they would actually create

449
00:33:42,860 --> 00:33:46,030
another function and they call this one set.

450
00:33:46,070 --> 00:33:51,630
So you can see public double get salary and this is going to return.

451
00:33:51,680 --> 00:33:56,420
But then this one can be void because I don't need to return anything when I'm sitting the salary.

452
00:33:56,420 --> 00:34:00,950
However I'm going to require that you tell me home What salary I'm setting for this person.

453
00:34:00,980 --> 00:34:03,270
So I need a value from use.

454
00:34:03,350 --> 00:34:04,220
I want to see.

455
00:34:04,220 --> 00:34:09,150
Send me a parameter and I'm going to say give me salary.

456
00:34:09,260 --> 00:34:12,600
Come on s and then no return.

457
00:34:12,600 --> 00:34:21,290
But I'm sitting the capital S salary which is my private member field to have the same value as the

458
00:34:21,290 --> 00:34:25,040
salary that is coming in through the parameters.

459
00:34:25,070 --> 00:34:27,650
So salaries equals a salary.

460
00:34:27,740 --> 00:34:35,270
So a good naming conviction actually when it comes to private members is that you use on the score and

461
00:34:35,270 --> 00:34:36,670
not capital letters.

462
00:34:36,700 --> 00:34:43,160
So the public accessible ones would have the capital letter but once it's private to use an underscore

463
00:34:43,190 --> 00:34:44,230
and come on.

464
00:34:44,270 --> 00:34:48,920
So let me just change that's out and I mean you saw that it worked either way.

465
00:34:48,950 --> 00:34:53,260
So it's not so much of it's working versus not working is just a matter of.

466
00:34:53,270 --> 00:34:58,300
This is the standard so somebody else comes along looks out to your code they know exactly what they're

467
00:34:58,310 --> 00:35:00,180
looking at at a glance.

468
00:35:00,180 --> 00:35:00,910
All right.

469
00:35:00,980 --> 00:35:07,850
So private double salary that his or one private member field and we need a function to get the value

470
00:35:07,850 --> 00:35:11,580
that is there how we need a function to sit of value in there.

471
00:35:11,630 --> 00:35:21,770
So back in the program I can see a person Dot and I will only have access to any methods or properties

472
00:35:21,770 --> 00:35:34,860
that have the public identifier or access modifier sorry of indicator on their declaration

473
00:35:44,010 --> 00:35:46,530
so that's it for this very very

474
00:35:54,080 --> 00:35:58,880
so that's it for this quick introduction to classes and objects in C sharp.

475
00:35:58,880 --> 00:36:01,190
I'm going to encourage you to just think of anything.

476
00:36:01,190 --> 00:36:08,480
Think of a pit and then define a class called pit and then start writing all the different properties.

477
00:36:08,480 --> 00:36:16,250
And I like to think of the properties as the knowns and the methods as the verb right so the known would

478
00:36:16,250 --> 00:36:18,510
be like something that is there.

479
00:36:18,650 --> 00:36:21,950
So a box is always wins out but then it's always lands after birth.

480
00:36:22,010 --> 00:36:28,250
It's always good to have a height but then getting the volume and getting the area or in the air in

481
00:36:28,250 --> 00:36:35,750
the student of the person getting the salary or setting the salary or even getting full name.

482
00:36:35,750 --> 00:36:37,150
So let me just type that one.

483
00:36:37,170 --> 00:36:40,930
I want you to complete this string.

484
00:36:40,970 --> 00:36:42,410
Public string.

485
00:36:42,410 --> 00:36:44,440
Get full name.

486
00:36:44,900 --> 00:36:53,210
So I want you to define this function to get this person's full name and I want you to share your code

487
00:36:53,210 --> 00:36:53,790
with me.

488
00:36:53,900 --> 00:36:57,380
And then we can go through any difficulty you had together.

489
00:36:57,380 --> 00:37:02,270
So once again the methods are more like verbs because this is an action getting the full name is an

490
00:37:02,300 --> 00:37:04,280
action but the name is always there.

491
00:37:04,280 --> 00:37:05,920
That's more like unknown.

492
00:37:06,010 --> 00:37:08,470
All right so that's a challenge for you.

493
00:37:08,720 --> 00:37:09,920
Let me know if you have any.