Would you like to inspect the original subtitles? These are the user uploaded subtitles that are being translated: 1 00:00:00,210 --> 00:00:05,400 Hi, in this lecture you're going to learn about variables. So what is a variable? 3 00:00:05,400 --> 00:00:10,980 Well a variable is like a container where you can store various data types 5 00:00:10,980 --> 00:00:18,539 in Python for instance this program now this doesn't have any variable in it for 7 00:00:18,539 --> 00:00:23,699 now, so let me try and execute it and you'll see that this prints out of the 9 00:00:23,699 --> 00:00:29,609 hello string. String is a data type, but we'll cover that later. Now what is the 11 00:00:29,609 --> 00:00:38,790 variable? Well and variables will keep your code more organized. Let me create a 13 00:00:38,790 --> 00:00:45,149 variable here, greeting so you can call your variables whatever you like you can 15 00:00:45,149 --> 00:00:50,070 give them any name however there are some naming rules which I'll mention in 17 00:00:50,070 --> 00:00:55,739 just a bit, so let me create this variable for now. I'll store in this 19 00:00:55,739 --> 00:01:01,980 variable, I said variables are like containers so I'll store this text in the 21 00:01:01,980 --> 00:01:07,799 variable greeting and then what I do is instead of doing print hello I'll do 23 00:01:07,799 --> 00:01:15,570 print greeting and save the script ctrl s and then go through the command line, 25 00:01:15,570 --> 00:01:22,229 the upper arrow key, enter to execute and you get the same output. So this is how 27 00:01:22,229 --> 00:01:26,670 you create a variable you don't use any quotes because when you use quotes you 29 00:01:26,670 --> 00:01:34,229 are creating a string data type not a variable and you can also use a dash 31 00:01:34,229 --> 00:01:43,439 before the variable that would also be fine so you get the output correctly 33 00:01:43,439 --> 00:01:50,549 but you cannot use numbers before the variable ctrl s to save, execute and get 35 00:01:50,549 --> 00:01:56,820 an invalid syntax, so this syntax is not valid in Python, but you can use numbers 37 00:01:56,820 --> 00:02:09,119 after or between the variable name let's say here greeting2. So that would 39 00:02:09,119 --> 00:02:13,860 be fine to use so that's the condition about naming 41 00:02:13,860 --> 00:02:19,470 your variables, you can start them with a letter or a, or an underscore. Now if 43 00:02:19,470 --> 00:02:24,720 you're not experienced with programming you may still be confused on why do we 45 00:02:24,720 --> 00:02:31,370 use these variables? Well this is a very simple program, actually very useless, but 47 00:02:31,370 --> 00:02:37,140 normally your programs will interact with your users. That is what we call a 49 00:02:37,140 --> 00:02:43,140 real program. You create a program to give it to people so they can interact 51 00:02:43,140 --> 00:02:48,810 with the program they can generate all different outputs and so on, so let's go 53 00:02:48,810 --> 00:02:57,060 Ahead and make this program more dynamic, so what I'll do here is I'll get the text 55 00:02:57,060 --> 00:03:03,720 from the user interactively. To do that you need to use the input function, this 57 00:03:03,720 --> 00:03:09,959 is also a Python function and inside the function you can enter a message to the 59 00:03:09,959 --> 00:03:16,640 user so let's say write a greeting. A column and make some space there and then 61 00:03:20,519 --> 00:03:28,290 you print greeting2, save the script. Execute and now the program is asking 63 00:03:28,290 --> 00:03:36,060 us to enter some input so let's go ahead and say hi this time and we get the output 65 00:03:36,060 --> 00:03:42,150 Printed out in here, hi, so what happened here is we created a variable 67 00:03:42,150 --> 00:03:49,320 and that variable will store the value that the user submits in the command line 69 00:03:49,320 --> 00:03:55,590 here, in the terminal so the user submitted the hi text and this text will be 71 00:03:55,590 --> 00:04:00,989 stored in this variable so as I said variables are like containers and then can 73 00:04:00,989 --> 00:04:06,390 use this text in various ways, but in this scenario I'm just passing it to the 75 00:04:06,390 --> 00:04:12,030 print function, so I want to print it out on the terminal here and the print 77 00:04:12,030 --> 00:04:16,709 function will get the value that is stored in the greeting2 variable and 79 00:04:16,709 --> 00:04:22,650 print it out on the terminal. That's it. And yeah, I'd like to close this lecture 81 00:04:22,650 --> 00:04:27,110 now and I'll see you in the next lecture. 4962