WEBVTT 00:00.960 --> 00:06.680 Now that you know how to execute your first program, let's move for the next part, which is Python 00:06.680 --> 00:07.200 variable. 00:07.240 --> 00:10.200 Okay, so let me create a new file. 00:10.560 --> 00:11.000 Okay. 00:12.200 --> 00:14.080 Right here I'm going to create a new file. 00:14.080 --> 00:19.440 It is going to be variables.py okay. 00:19.480 --> 00:22.240 How can we create a variable or first what is a variable. 00:22.280 --> 00:22.640 Okay. 00:24.280 --> 00:26.240 Uh what is a variable okay. 00:29.720 --> 00:32.160 Are variable or variables. 00:32.280 --> 00:37.160 Are containers okay for storing data values. 00:37.440 --> 00:38.360 Okay. 00:38.400 --> 00:45.760 For example we have x which is equal to a number like 34 right. 00:45.800 --> 00:48.560 Now this x it is a variable okay. 00:48.600 --> 00:55.160 That contains or store this data which is 34 inside x okay. 00:55.200 --> 00:59.840 Whenever I use x it will give me a value which is 34. 00:59.880 --> 01:00.560 And that is all. 01:00.560 --> 01:02.560 This is all about variable. 01:02.600 --> 01:03.440 Not really. 01:04.200 --> 01:07.480 We have more about variables okay. 01:09.440 --> 01:11.940 Let me show you here. 01:11.980 --> 01:12.700 Okay. 01:12.740 --> 01:14.580 So x is equal to 34. 01:14.620 --> 01:16.820 It's a variable that contains integer. 01:16.860 --> 01:17.540 Okay. 01:17.580 --> 01:18.940 Integer is a number. 01:18.980 --> 01:19.260 Okay. 01:19.300 --> 01:21.620 Any number could have could be integer. 01:22.340 --> 01:26.180 And also we have something else like name. 01:26.220 --> 01:27.620 It is equal to. 01:27.660 --> 01:29.100 For example name it. 01:29.140 --> 01:29.700 Okay. 01:29.740 --> 01:32.620 So now name is also a variable that contain a string. 01:32.780 --> 01:34.180 This is called string. 01:34.260 --> 01:38.100 Anything that has these quotation marks or strings. 01:38.140 --> 01:38.780 Okay. 01:38.820 --> 01:43.420 Now this name is a value for this okay. 01:43.460 --> 01:46.460 For this variable name that is a value for name. 01:47.580 --> 01:52.220 Now if I want to see the value for this board I could use print. 01:52.220 --> 01:53.540 And then let's see x. 01:54.100 --> 01:56.540 So let's save it. 01:56.780 --> 02:03.260 And here let me use Python variable.py hit enter. 02:03.300 --> 02:06.300 Now you see we have 34 right here. 02:06.860 --> 02:11.140 And what if I see if I want to see name here. 02:11.140 --> 02:15.180 And this time it must give me name okay. 02:15.220 --> 02:15.620 See. 02:16.580 --> 02:17.820 So these are variables. 02:18.060 --> 02:28.160 And Also, there is some rule that you need to be careful about them while naming a variable. 02:28.200 --> 02:28.760 Okay. 02:28.800 --> 02:34.000 For example, our label name must start with a letter or an underscore. 02:34.240 --> 02:41.000 For example, you see here okay name it name starts with n n is a letter okay. 02:42.120 --> 02:46.320 And also it will start with underscore okay. 02:46.360 --> 02:47.680 Now it's also okay. 02:47.920 --> 02:50.800 And it will not give me an error if I execute this. 02:51.640 --> 02:52.200 Let's see. 02:54.600 --> 02:56.520 A name is defined. 02:56.560 --> 02:58.680 Did you mean name okay. 02:58.920 --> 02:59.840 That is here. 02:59.880 --> 03:01.680 See right now I'm printing name. 03:01.680 --> 03:03.760 And there is no name like this. 03:03.760 --> 03:05.960 I must add an underscore at the beginning. 03:06.400 --> 03:06.800 Now. 03:09.480 --> 03:11.920 Now if I execute this, it will give me name. 03:12.080 --> 03:12.480 Okay. 03:12.800 --> 03:20.320 So the first rule, the first number, the first letter could be a letter or underscore is one of the 03:20.320 --> 03:20.600 rule. 03:20.600 --> 03:22.880 The second rule is a variable name. 03:22.920 --> 03:25.160 Cannot start with a number okay. 03:25.200 --> 03:33.740 For example if you give two here And also to hear now if I execute this, it will give me an error. 03:34.380 --> 03:39.340 And you see that it says syntax error invalid decimal literal. 03:39.380 --> 03:39.740 Okay. 03:40.020 --> 03:44.020 That is because I use a number at the beginning of a variable. 03:44.060 --> 03:44.540 Okay. 03:44.580 --> 03:45.500 Name of variable. 03:45.540 --> 03:51.540 You cannot use name a number at the beginning of a variable. 03:51.660 --> 03:52.740 This is the second one. 03:52.900 --> 03:55.380 And let's go with the third one. 03:55.420 --> 04:01.820 Our variable name can only contain alpha numeric character and underscore. 04:02.940 --> 04:04.460 And that is all. 04:05.700 --> 04:13.580 How it can contain okay letter or alphabet from A to Z. 04:13.620 --> 04:16.540 Number from 0 to 9 and underscore okay. 04:16.580 --> 04:20.940 It cannot contain something like dollar sign or something like this. 04:21.220 --> 04:22.780 It cannot contain them okay. 04:23.380 --> 04:24.580 So this is the third one. 04:24.580 --> 04:27.980 And the fourth one is variable names are case sensitive. 04:28.140 --> 04:29.300 It is very important. 04:29.340 --> 04:32.020 For example we have h which is equal to. 04:35.180 --> 04:36.620 For example 12 okay. 04:36.820 --> 04:43.480 And also we have another edge with capital A and it is equal to for example, 90. 04:43.520 --> 04:45.120 Now if I print. 04:47.240 --> 04:54.480 For example h it will give me 12 because these two are not the same okay. 04:54.520 --> 04:58.040 And variable names are case sensitive. 04:58.080 --> 05:06.040 Now if I execute and run the other one which is this one, and this time you know that it will give 05:06.040 --> 05:08.480 me, uh, other thing. 05:08.520 --> 05:11.960 Let me save it first and then run it. 05:12.040 --> 05:17.280 You see, this is the number which is a value for age with capital A. 05:17.320 --> 05:26.400 So this was about how you can create a variable and also for rules, uh, about naming a variable. 05:26.440 --> 05:26.880 Okay. 05:27.200 --> 05:29.160 So this was all about variable. 05:29.360 --> 05:31.040 I hope you learn it. 05:31.040 --> 05:37.520 And through the course you will learn it a lot because we are in each lecture we are using variables. 05:37.560 --> 05:38.360 Okay. 05:38.400 --> 05:44.680 So if you don't get it don't be worried because because you will get it okay. 05:44.720 --> 05:45.960 It is very easy. 05:45.960 --> 05:47.400 So I will see in the next lecture.