1 00:00:00,630 --> 00:00:11,990 Hello and welcome to this lecture on dictionaries in C sharp dictionaries are a special type of list 2 00:00:13,770 --> 00:00:23,310 and every value in the list has a key which is also a variable 3 00:00:28,890 --> 00:00:33,940 a great example of a dictionary is a phone book. 4 00:00:36,150 --> 00:00:45,180 I have got used to open so I'm going to create a new project just the console project so I can illustrate 5 00:00:45,690 --> 00:00:50,340 how we can create an example of a dictionary. 6 00:00:50,400 --> 00:00:57,690 So I'm going to click on the new project link here and wait for the templates to load. 7 00:00:57,740 --> 00:01:04,610 I got visual C sharp I'm going to select console application so we've got a default name here. 8 00:01:04,620 --> 00:01:10,230 I'm just going to get rid of that and typing dictionaries 9 00:01:15,750 --> 00:01:17,730 and click OK. 10 00:01:18,210 --> 00:01:24,210 So we wait for the template to load. 11 00:01:26,290 --> 00:01:26,620 Or. 12 00:01:26,640 --> 00:01:30,140 Visual Studio has generated a stub. 13 00:01:30,270 --> 00:01:31,410 That is a sample code. 14 00:01:31,860 --> 00:01:39,000 So in between here is where we're going to write the code any code we have or write it in between this 15 00:01:39,390 --> 00:01:41,330 curly braces. 16 00:01:41,400 --> 00:01:46,580 So the first thing we need to do is to define a dictionary. 17 00:01:46,860 --> 00:01:56,340 And when you define a dictionary you need to specify a key and the type of the value. 18 00:01:56,490 --> 00:02:04,730 For example you you have to specify a string if it's going to be a string or an integer. 19 00:02:06,360 --> 00:02:07,930 OK let's begin. 20 00:02:07,950 --> 00:02:13,630 So we'll start with a named dictionary. 21 00:02:13,830 --> 00:02:18,990 Notice intelligence has given us a clue that I want to specify a dictionary. 22 00:02:18,990 --> 00:02:28,070 So we do that and then we have you have to specified angle brackets in between these brackets. 23 00:02:28,080 --> 00:02:31,470 You have to specify two values. 24 00:02:31,500 --> 00:02:36,100 The first will be the data type. 25 00:02:36,120 --> 00:02:37,470 This is a string 26 00:02:40,590 --> 00:02:47,040 so don't forget with a dictionary you have to have a data type and also you have to have a key. 27 00:02:48,660 --> 00:02:52,540 So we need to have that type of the key. 28 00:02:52,580 --> 00:02:57,150 The type is going to be a string and that type of the value. 29 00:02:57,590 --> 00:02:59,090 So there are two things here. 30 00:02:59,320 --> 00:03:04,750 A type of the key and that type of the value. 31 00:03:05,430 --> 00:03:14,790 So the value is going to be an integer and the type of integer is going to be a long data type. 32 00:03:14,790 --> 00:03:21,280 So now I have yeah if I'm still in the process of defining it. 33 00:03:21,330 --> 00:03:34,340 So you have to separate the key type from the value the type of value separate that with a comma. 34 00:03:34,410 --> 00:03:36,970 The next thing you do you give the dictionary a name. 35 00:03:36,990 --> 00:03:50,700 I'm going to call it phone book and I'm going to create a new instance with new dictionary 36 00:03:55,120 --> 00:03:58,070 that will pass in the type 37 00:04:05,460 --> 00:04:11,230 comma and the value the value is going to be an integer. 38 00:04:11,990 --> 00:04:19,760 And at the end you put parentheses and a semicolon. 39 00:04:20,120 --> 00:04:24,750 So on line 14 here we have defined a dictionary. 40 00:04:25,210 --> 00:04:26,070 OK. 41 00:04:26,270 --> 00:04:36,650 So notice in the definition we have specified the type of key and that type of value. 42 00:04:37,310 --> 00:04:45,770 So in this case the key is the string while the value is the integer which is the long long case an 43 00:04:45,860 --> 00:04:48,320 integer. 44 00:04:48,710 --> 00:04:56,750 Now that we've defined the dictionary we need to find a way to add value to the dictionary. 45 00:04:56,780 --> 00:04:59,890 Now they are two basic ways. 46 00:04:59,960 --> 00:05:04,960 You can use to add a single value to a dictionary. 47 00:05:05,120 --> 00:05:11,910 You can use brackets the brackets operator or you can use the add method. 48 00:05:11,930 --> 00:05:14,440 So we're going to try both. 49 00:05:14,450 --> 00:05:18,160 So let's go ahead and do that. 50 00:05:18,320 --> 00:05:20,300 I want to start with the add method first. 51 00:05:20,310 --> 00:05:29,480 So I've already defined the dictionary as phonebook so I type in phonebook which is here is picked it 52 00:05:29,480 --> 00:05:38,560 up and I need to attach to the add method. 53 00:05:38,630 --> 00:05:39,150 OK. 54 00:05:39,150 --> 00:05:43,900 And a name inside the parentheses are passing the valley. 55 00:05:44,340 --> 00:05:47,070 So say Alex 56 00:05:50,190 --> 00:05:59,580 that would be the type which is a string and then I need to specify the value which is an integer so 57 00:05:59,580 --> 00:06:05,260 I'll type in say for 1 5 5 4 3. 58 00:06:05,640 --> 00:06:15,240 His phone number is not accurate by the way is just an example for number and type pain a semicolon 59 00:06:15,540 --> 00:06:15,990 at the end. 60 00:06:15,990 --> 00:06:21,900 So we have now added this value to the dictionary. 61 00:06:21,900 --> 00:06:27,360 So let's try this second method the second method is to use the brackets operator. 62 00:06:27,450 --> 00:06:31,200 So again I type in the name of the dictionary 63 00:06:34,110 --> 00:06:35,760 and then I'll type in the brackets. 64 00:06:35,760 --> 00:06:43,020 Operator inside the brackets operator I can type in the name. 65 00:06:43,020 --> 00:06:51,630 This will be the string value of comma and then I specify with the brackets. 66 00:06:51,650 --> 00:06:52,350 Operator 67 00:06:55,820 --> 00:07:04,100 You specify an equals to use on equals 2 to assign the value. 68 00:07:04,100 --> 00:07:07,010 So I say 5 1 2 3. 69 00:07:07,010 --> 00:07:09,820 Again this is not a real number. 70 00:07:09,980 --> 00:07:12,230 It's a fictitious number. 71 00:07:12,260 --> 00:07:19,470 So we've now assigned single values to our phonebook dictionary vide two methods we using the add method. 72 00:07:19,490 --> 00:07:23,370 And we also using the brackets operator. 73 00:07:24,560 --> 00:07:31,850 So let's test this to to test it for it to display on the console are retain these two lines of code 74 00:07:31,850 --> 00:07:39,200 here console the right line of pass state phone book which is the name of the form of the dictionary 75 00:07:39,680 --> 00:07:46,820 and then are passed in the value Alex of use the console the red line so that when the application runs 76 00:07:47,330 --> 00:07:50,970 the details remain displayed on the screen. 77 00:07:51,080 --> 00:07:57,890 If I don't use the console the red line it will just execute and the details disappears from the screen. 78 00:07:57,890 --> 00:08:03,860 So this console the read line and enables the details to stay on the screen. 79 00:08:04,070 --> 00:08:08,120 Once the code has been executed. 80 00:08:08,480 --> 00:08:15,250 So what the code on line eighteen is saying that it will display the phone number for Alex. 81 00:08:15,320 --> 00:08:18,130 So let's run that click on the start. 82 00:08:18,530 --> 00:08:24,530 As you can see here either displayed the phone number for Alex. 83 00:08:24,590 --> 00:08:31,040 So that's how you define a dictionary in C sharp. 84 00:08:31,040 --> 00:08:33,590 Thanks for watching and bye for now.