1 00:00:00,630 --> 00:00:02,850 Hello and welcome to this lecture. 2 00:00:03,960 --> 00:00:06,510 What are switch statements. 3 00:00:06,510 --> 00:00:18,610 Switch statements are basically used to perform different actions based on different conditions. 4 00:00:18,660 --> 00:00:25,240 Let's have a look at the syntax or how a switch statement is written. 5 00:00:25,740 --> 00:00:34,080 So this is a basic switch syntax basically describing how to write a switch statement. 6 00:00:34,260 --> 00:00:43,050 So you begin with the words switch and then you have the expression which is the condition that must 7 00:00:43,050 --> 00:00:44,030 be met. 8 00:00:44,290 --> 00:00:52,740 For each of these block of course so with this switch statement he can have various cases and each of 9 00:00:52,740 --> 00:00:55,530 the cases has a block of code. 10 00:00:55,680 --> 00:01:06,690 So if case a for example matches the expression here it will execute this code block inside the first 11 00:01:06,690 --> 00:01:07,480 case. 12 00:01:07,770 --> 00:01:16,320 If he doesn't if Kobe matches the expression it will execute the code in Block B and so on. 13 00:01:18,120 --> 00:01:29,390 So based on any of the code blocks matching the expression the code in that case will be executed. 14 00:01:29,460 --> 00:01:31,390 Notice there is a break. 15 00:01:31,610 --> 00:01:32,910 Key word here. 16 00:01:33,030 --> 00:01:34,370 This break. 17 00:01:34,440 --> 00:01:43,200 Key word basically breaks out of the switch block block when an expression has been matched that means 18 00:01:43,740 --> 00:01:51,990 the code will stop execution and none of the other cases the code in the other block of cases will execute. 19 00:01:53,070 --> 00:02:01,590 So what that means basically if a match is found in either of these cases for the expression then the 20 00:02:01,590 --> 00:02:03,980 code once to call has been executed. 21 00:02:04,020 --> 00:02:10,500 He breaks out the switch that means it terminates a break is useful. 22 00:02:10,500 --> 00:02:19,170 He can save a lot of time for execution because it ignores the execution of the rest of the code block 23 00:02:19,380 --> 00:02:20,400 within the switch. 24 00:02:20,400 --> 00:02:30,420 Once he's found a match it no longer needs to execute the other code blocks within the switch. 25 00:02:30,420 --> 00:02:37,890 Also the last case in the switch block you don't necessarily have to put a break in that because the 26 00:02:37,890 --> 00:02:45,570 block will end there anyway so there's no need to put a break but it's just good practice. 27 00:02:45,570 --> 00:02:49,860 Also notice there is a default key word here. 28 00:02:49,860 --> 00:02:59,190 The default key word basically is used to specify the code that will run if there is no match in the 29 00:02:59,190 --> 00:02:59,670 case. 30 00:02:59,670 --> 00:03:07,830 If for example if none of the cases matches the expression then you need to specify code that will run 31 00:03:08,220 --> 00:03:12,260 inside the default keyword. 32 00:03:12,270 --> 00:03:19,890 Also the default keyword doesn't necessarily have to be the last case in the switch. 33 00:03:19,890 --> 00:03:20,310 BLOCK 34 00:03:23,390 --> 00:03:30,920 I have got visual studio open so I'm going to create a new Windows application project and use that 35 00:03:30,920 --> 00:03:34,980 to illustrate how a switch statement works. 36 00:03:35,030 --> 00:03:41,430 So I'm going to click on the new project link here and I'll wait for the templates to load. 37 00:03:41,430 --> 00:03:43,460 So these templates are loaded. 38 00:03:43,550 --> 00:03:51,470 Make sure you go visual see sharp selected and also make sure we've got windows form applications selected. 39 00:03:51,470 --> 00:04:00,780 So in the name here I'm going to change the default name and I'm going to just type switch and click 40 00:04:01,720 --> 00:04:10,740 OK and I'll wait for Visual Studio to create the project. 41 00:04:11,510 --> 00:04:16,970 So Visual Studio is created a project and given us a form as well. 42 00:04:16,970 --> 00:04:20,180 So I'm just going to expand this form a little bit. 43 00:04:20,240 --> 00:04:23,270 I'm going to add a button to this form. 44 00:04:23,270 --> 00:04:29,160 Just going to try again button here and just make that peek a little bit 45 00:04:36,520 --> 00:04:40,510 am just going to go back into the design view 46 00:04:43,120 --> 00:04:47,680 I clicked on the button by clicking on the button what it did. 47 00:04:47,920 --> 00:04:52,570 It generated this event handler here. 48 00:04:52,690 --> 00:05:00,970 This is a stop it stop meaning it's an empty method so that we can to write our code between this curly 49 00:05:01,390 --> 00:05:05,390 braces here for the button click event. 50 00:05:05,710 --> 00:05:08,700 So I'm just gonna pop back into the form designer. 51 00:05:08,700 --> 00:05:21,240 I just want to change the name of this so I right click properties I'll change that to the day of the 52 00:05:21,240 --> 00:05:21,690 week. 53 00:05:29,570 --> 00:05:30,070 Okay. 54 00:05:30,700 --> 00:05:34,450 And I go back into my form designer. 55 00:05:35,000 --> 00:05:47,470 Someone to start by creating a variable component is gonna be an integer and we'll call it foul. 56 00:05:48,470 --> 00:05:51,410 And I'll set the value to 57 00:05:53,630 --> 00:05:55,010 say 1 58 00:06:00,840 --> 00:06:03,680 set of values to 1. 59 00:06:04,860 --> 00:06:07,660 So let's start implementing this sweet statement. 60 00:06:07,740 --> 00:06:10,350 So to begin I just type in the word switch 61 00:06:18,620 --> 00:06:24,240 and then followed by the variable I've just created. 62 00:06:24,240 --> 00:06:25,920 Followed by this variable. 63 00:06:25,920 --> 00:06:33,630 So this is very variable is going to be the expression that will be evaluated for the switch. 64 00:06:33,630 --> 00:06:41,970 So I just need to come here and pull my curly braces in between the curly braces is where I will define 65 00:06:42,000 --> 00:06:49,290 the various cases for the switch statement to save time. 66 00:06:49,290 --> 00:06:56,070 I've already written the statement for the switch to this. 67 00:06:56,070 --> 00:07:00,050 First I started off with creating a variable. 68 00:07:00,040 --> 00:07:05,250 So I created a variable called Val and gave it a value of 1. 69 00:07:05,260 --> 00:07:08,160 This is where I switch step and start from. 70 00:07:08,160 --> 00:07:15,130 So you start with the word switch and then you pass in the expression the expression here is a variable. 71 00:07:15,180 --> 00:07:20,320 So these are the cases you can have as many cases as you want in a sweet statement. 72 00:07:20,340 --> 00:07:23,460 I've got seven cases in the switch statement. 73 00:07:23,460 --> 00:07:29,670 Basically this is a case of the days of the week. 74 00:07:29,790 --> 00:07:38,490 So there are seven days in a week and I'm giving each day of the week a case representation. 75 00:07:38,880 --> 00:07:43,050 So the variable here has a value of 1. 76 00:07:43,140 --> 00:07:53,550 So I'm saying that in each of these cases the which ever case matches the expression that code will 77 00:07:53,550 --> 00:07:58,320 be executed and the other code will not execute. 78 00:07:58,980 --> 00:08:08,280 So here as you can see because the the value of the Variable value close to 1 the first case will be 79 00:08:08,280 --> 00:08:15,080 executed with code will show the day is Sunday. 80 00:08:15,330 --> 00:08:21,570 If the value was to then Monday will be the code block inside. 81 00:08:21,570 --> 00:08:26,700 Case 2 which is Monday will be executed because that matches the variable. 82 00:08:26,700 --> 00:08:32,010 If the variable is set to 2 So let's test that out. 83 00:08:32,160 --> 00:08:41,060 Also if none of these cases matches then it will execute the code in the default block okay. 84 00:08:41,070 --> 00:08:45,370 So as you can see Case 1 here we've got Sunday. 85 00:08:45,660 --> 00:08:46,900 So let's execute that. 86 00:08:46,980 --> 00:08:50,230 I expect the code to show the day is Sunday. 87 00:08:51,090 --> 00:08:59,470 Let's run that and see give it a few minutes to load up. 88 00:09:01,260 --> 00:09:02,930 So this is our button. 89 00:09:03,040 --> 00:09:13,600 So if I click this button it should show Sunday C the day is Sunday. 90 00:09:13,660 --> 00:09:14,140 That's it. 91 00:09:14,260 --> 00:09:16,270 So the code is executed. 92 00:09:16,780 --> 00:09:25,310 So if I was to change his value for example I change a value to say six. 93 00:09:25,450 --> 00:09:35,950 For example he should show the day is Friday because case six will match that expression as give it 94 00:09:35,950 --> 00:09:40,540 a go start click on day of the week. 95 00:09:40,560 --> 00:09:43,250 As you can see he says the day is Friday. 96 00:09:43,530 --> 00:09:54,390 And that's because the the expression in the switch statement here matches the case number six because 97 00:09:54,390 --> 00:09:57,710 of the variable value is six. 98 00:09:57,720 --> 00:10:02,350 So that's basically how a switch statement works. 99 00:10:02,370 --> 00:10:08,000 So I hope the lecture has been useful if there are any questions please let me know. 100 00:10:08,610 --> 00:10:09,090 Thank you.