1
00:00:00,120 --> 00:00:03,090
‫-: Hi. Within this lecture we are going to

2
00:00:03,090 --> 00:00:05,730
‫learn a new structure called Switch.

3
00:00:05,730 --> 00:00:09,840
‫And this is basically the same thing with 'if' statements,

4
00:00:09,840 --> 00:00:12,960
‫but it's a little bit more clear,

5
00:00:12,960 --> 00:00:15,990
‫when it comes to 'as if' statements.

6
00:00:15,990 --> 00:00:19,362
‫So if you have a lot of 'as if' statements

7
00:00:19,362 --> 00:00:23,700
‫in a given condition in a given 'if' control

8
00:00:23,700 --> 00:00:26,850
‫then you may want to check out Switch.

9
00:00:26,850 --> 00:00:29,910
‫So best way to explain this is with an example.

10
00:00:29,910 --> 00:00:33,720
‫So I'm gonna create a 'day' into the row here

11
00:00:33,720 --> 00:00:36,390
‫and day will be '1' at first.

12
00:00:36,390 --> 00:00:40,260
‫So I'm gonna create another day string

13
00:00:40,260 --> 00:00:41,850
‫and I'm going to check for those.

14
00:00:41,850 --> 00:00:45,150
‫If day is '1', then I'm gonna print out 'Monday'.

15
00:00:45,150 --> 00:00:48,570
‫If day is '2', then I'm gonna print out 'Tuesday'.

16
00:00:48,570 --> 00:00:51,480
‫Okay? So let me create a new day string

17
00:00:51,480 --> 00:00:54,270
‫over here and this will be empty at first

18
00:00:54,270 --> 00:00:59,270
‫like an empty string with only two double quotation marks.

19
00:00:59,520 --> 00:01:03,480
‫And then later on I suggest you pause the video

20
00:01:03,480 --> 00:01:06,540
‫and try to do this with 'if' statements.

21
00:01:06,540 --> 00:01:09,300
‫Okay? Because it's fairly easy.

22
00:01:09,300 --> 00:01:14,300
‫If day is '1', then day string will be 'Monday'.

23
00:01:14,790 --> 00:01:19,790
‫Okay? And I'm going to print out this day string later on.

24
00:01:20,190 --> 00:01:23,730
‫We shouldn't bother printing out at this point.

25
00:01:23,730 --> 00:01:28,350
‫We can do it at the end of the 'if' control like this.

26
00:01:28,350 --> 00:01:33,350
‫Else if day is '2', day string would be Tuesday, okay?

27
00:01:33,720 --> 00:01:36,870
‫And else if day is '3',

28
00:01:36,870 --> 00:01:40,827
‫the day string will be something like 'Wednesday.'

29
00:01:41,730 --> 00:01:46,200
‫Okay? And I'm not gonna do the whole thing over here.

30
00:01:46,200 --> 00:01:50,340
‫I'm gonna skip Thursday, Friday, Saturday.

31
00:01:50,340 --> 00:01:54,750
‫Maybe we can just go for a Sunday with an 'else'. Okay?

32
00:01:54,750 --> 00:01:59,490
‫So maybe we forgot about the day '4', '5', and '6'

33
00:01:59,490 --> 00:02:04,490
‫and we just go directly to this Sunday over here.

34
00:02:05,190 --> 00:02:09,420
‫Of course you can do the whole thing in your own example

35
00:02:09,420 --> 00:02:11,430
‫but I'm not going to do that

36
00:02:11,430 --> 00:02:14,550
‫in order not to make it way too much.

37
00:02:14,550 --> 00:02:17,190
‫But this should work fine.

38
00:02:17,190 --> 00:02:18,810
‫Let me run this and here you go.

39
00:02:18,810 --> 00:02:21,697
‫We see the 'Monday', let me change it to '2'

40
00:02:21,697 --> 00:02:25,470
‫and we're gonna see Tuesday, right?

41
00:02:25,470 --> 00:02:26,303
‫Here you go.

42
00:02:26,303 --> 00:02:27,243
‫We see the Tuesday.

43
00:02:28,650 --> 00:02:33,650
‫Great. Now I'm gonna do the same thing but with 'switch.'

44
00:02:34,860 --> 00:02:39,090
‫So sometimes it might look a little bit more

45
00:02:39,090 --> 00:02:42,817
‫complicated even to you then maybe you don't

46
00:02:42,817 --> 00:02:47,100
‫prefer using Switch, but sometimes people find it much

47
00:02:47,100 --> 00:02:48,060
‫more easier.

48
00:02:48,060 --> 00:02:50,280
‫So I'm going to show you anyway.

49
00:02:50,280 --> 00:02:53,460
‫So you write 'switch' and you write the value

50
00:02:53,460 --> 00:02:56,190
‫that you may want to check for.

51
00:02:56,190 --> 00:02:58,520
‫Okay, we are gonna check for day as

52
00:02:58,520 --> 00:03:01,440
‫we we did in the 'if' statement.

53
00:03:01,440 --> 00:03:05,943
‫So if day is one, then we are gonna do something.

54
00:03:06,780 --> 00:03:09,445
‫And over here we use 'case'

55
00:03:09,445 --> 00:03:11,070
‫keyword,

56
00:03:11,070 --> 00:03:12,840
‫if case is

57
00:03:12,840 --> 00:03:13,673
‫'1'.

58
00:03:14,520 --> 00:03:19,470
‫So 'case 1' means if day is '1' in switch

59
00:03:19,470 --> 00:03:23,220
‫and rather than same column, we use a column over here

60
00:03:23,220 --> 00:03:27,140
‫and we don't even use a curly brace and this is one

61
00:03:27,140 --> 00:03:31,590
‫of the unique places that we use column and just go

62
00:03:31,590 --> 00:03:36,590
‫to the next line and write whatever we want like this.

63
00:03:36,840 --> 00:03:39,390
‫And we are writing break over here,

64
00:03:39,390 --> 00:03:42,000
‫it means that we are done over here.

65
00:03:42,000 --> 00:03:44,850
‫Just break out of the switch loop

66
00:03:44,850 --> 00:03:47,670
‫because we got what we want, right?

67
00:03:47,670 --> 00:03:50,820
‫If case is '1', we are gonna change the day string

68
00:03:50,820 --> 00:03:55,020
‫to Monday and we're gonna break out of this.

69
00:03:55,020 --> 00:03:57,990
‫So this is how you work with Switch.

70
00:03:57,990 --> 00:04:00,600
‫We can just go along and say

71
00:04:00,600 --> 00:04:03,355
‫case '2' day string is Tuesday.

72
00:04:03,355 --> 00:04:07,350
‫Okay? And we're gonna break again.

73
00:04:07,350 --> 00:04:09,840
‫So we can go for case three.

74
00:04:09,840 --> 00:04:13,620
‫As you can see, it's a little bit more clear

75
00:04:13,620 --> 00:04:16,470
‫on the code when you first look into it

76
00:04:16,470 --> 00:04:19,890
‫like cases and it looks better.

77
00:04:19,890 --> 00:04:24,330
‫But sometimes it can be much more complicated

78
00:04:24,330 --> 00:04:27,930
‫than a simple 'if' and 'as if' control statement.

79
00:04:27,930 --> 00:04:30,150
‫So if you didn't like it, just don't use it,

80
00:04:30,150 --> 00:04:33,363
‫but if you see one, then don't be surprised.

81
00:04:34,320 --> 00:04:35,659
‫So over here,

82
00:04:35,659 --> 00:04:38,970
‫we did the case '1', '2', '3'.

83
00:04:38,970 --> 00:04:43,970
‫And also there is a case of default in the switch as well.

84
00:04:44,190 --> 00:04:47,248
‫Default means if none of this holds

85
00:04:47,248 --> 00:04:51,420
‫then, by default the value will be like this.

86
00:04:51,420 --> 00:04:53,400
‫For example, we can just make it equal

87
00:04:53,400 --> 00:04:57,390
‫to 'Sunday', it will be exactly the same like we did

88
00:04:57,390 --> 00:04:59,130
‫in the 'if' control, right?

89
00:04:59,130 --> 00:05:02,100
‫And we did the same thing with 'else.'

90
00:05:02,100 --> 00:05:04,650
‫So over here we are doing the same thing

91
00:05:04,650 --> 00:05:07,050
‫exactly the same thing actually.

92
00:05:07,050 --> 00:05:09,720
‫If day is '1', we are gonna make it print 'Monday'.

93
00:05:09,720 --> 00:05:12,720
‫If day is '2', we are gonna make it print Tuesday

94
00:05:12,720 --> 00:05:14,100
‫and 'Wednesday'.

95
00:05:14,100 --> 00:05:17,910
‫And if none of the conditions hold, then we're gonna make it

96
00:05:17,910 --> 00:05:21,507
‫even equal to actually 'Sunday.'

97
00:05:22,620 --> 00:05:24,210
‫So this is cool.

98
00:05:24,210 --> 00:05:27,450
‫So maybe we may want to delete everything in the

99
00:05:27,450 --> 00:05:32,430
‫'if' control right now and then we can just control this

100
00:05:32,430 --> 00:05:36,150
‫around this, execute this with switch control so

101
00:05:36,150 --> 00:05:39,573
‫that we can see if we get the same result or not.

102
00:05:40,500 --> 00:05:42,300
‫So I don't wanna delete this.

103
00:05:42,300 --> 00:05:47,300
‫So you can get, and you can just get the access from GitHub.

104
00:05:47,550 --> 00:05:50,520
‫I'm going to comment this out.

105
00:05:50,520 --> 00:05:52,710
‫So remember how we comment things out,

106
00:05:52,710 --> 00:05:55,530
‫how we write comments, we put double slashes,

107
00:05:55,530 --> 00:05:58,470
‫but there are so many lines over here.

108
00:05:58,470 --> 00:06:01,560
‫So actually there is a better way to do this

109
00:06:01,560 --> 00:06:03,330
‫with multiple lines.

110
00:06:03,330 --> 00:06:06,840
‫You put a '/' and a '*' and you put a '*'

111
00:06:06,840 --> 00:06:11,523
‫and a '/' whenever you may want to end this.

112
00:06:12,690 --> 00:06:17,490
‫So between those slash and starts, it's all commented out

113
00:06:17,490 --> 00:06:20,970
‫and it won't get executed once we run it.

114
00:06:20,970 --> 00:06:22,890
‫So now day is '2'

115
00:06:22,890 --> 00:06:26,460
‫and I'm executing this and I'm getting 'Tuesday'.

116
00:06:26,460 --> 00:06:29,190
‫Thanks to the switch that we have written.

117
00:06:29,190 --> 00:06:32,040
‫Let's try with '3', we are gonna get 'Wednesday'.

118
00:06:32,040 --> 00:06:34,350
‫Here you go, it works.

119
00:06:34,350 --> 00:06:36,270
‫So this is how we work

120
00:06:36,270 --> 00:06:40,487
‫with Switch and this is how we work with 'as if',

121
00:06:40,487 --> 00:06:45,030
‫and right now, you know how to work with both.

122
00:06:45,030 --> 00:06:47,970
‫You may choose your own way.

123
00:06:47,970 --> 00:06:51,243
‫Let's stop here and continue within the next lecture.