1 00:00:00,840 --> 00:00:06,230 In this video, you will learn how to do batch operations with Python. 2 00:00:06,240 --> 00:00:08,490 So what do I mean by that? 3 00:00:08,520 --> 00:00:11,990 Well, let's look at the current state of the program. 4 00:00:12,000 --> 00:00:17,590 So the program is asking the user three times for entering input. 5 00:00:17,610 --> 00:00:20,130 So we have three functions here. 6 00:00:21,110 --> 00:00:23,510 But as we mentioned, this is not sustainable. 7 00:00:23,870 --> 00:00:31,820 So what we want is to write the input function only once and somehow tell Python to execute it multiple 8 00:00:31,820 --> 00:00:32,570 times. 9 00:00:33,460 --> 00:00:34,750 So how do we do that? 10 00:00:34,870 --> 00:00:36,570 Well, let me show you that to you. 11 00:00:36,580 --> 00:00:38,290 I'll delete all these. 12 00:00:38,290 --> 00:00:40,150 We don't need them anymore. 13 00:00:42,810 --> 00:00:50,140 We only need the input function once here and then we make some space in here and we use a while. 14 00:00:50,160 --> 00:00:51,120 Look. 15 00:00:54,700 --> 00:01:01,960 So this starts with this wild keywords and then make a space and you put a condition. 16 00:01:03,190 --> 00:01:06,160 The conditions should be a true statement. 17 00:01:06,730 --> 00:01:12,100 Now, there are different ways to do this, but as a beginner, start with a simple statement such as 18 00:01:12,100 --> 00:01:14,590 to greater than one. 19 00:01:14,590 --> 00:01:16,950 So is to greater than one. 20 00:01:16,960 --> 00:01:17,650 Well. 21 00:01:17,680 --> 00:01:19,270 Yes, that's true. 22 00:01:19,270 --> 00:01:20,110 Always true. 23 00:01:20,140 --> 00:01:25,840 So when you put this column, I'll talk about that more in just a bit. 24 00:01:26,260 --> 00:01:31,690 And after the column, then you want to go here and you want to press space. 25 00:01:31,870 --> 00:01:33,250 Four times. 26 00:01:33,250 --> 00:01:35,980 One, two, three, four. 27 00:01:38,460 --> 00:01:41,850 And that is known as indentation. 28 00:01:42,450 --> 00:01:48,890 So that's part here for white spaces is is indentation and it is part of the syntax. 29 00:01:48,900 --> 00:01:51,180 So when you write this word keyword. 30 00:01:52,310 --> 00:02:00,710 Whatever comes down here, all the code is indented under that while keywords. 31 00:02:00,920 --> 00:02:02,810 So in this case. 32 00:02:04,510 --> 00:02:08,560 What we want to do is we want to ask the user for input. 33 00:02:08,830 --> 00:02:11,860 So I'll execute this now and you'll see what will happen. 34 00:02:12,100 --> 00:02:15,630 But first, let me rename this variable from 2 to 1 two. 35 00:02:15,640 --> 00:02:20,830 To do it makes more sense and right click and execute. 36 00:02:21,730 --> 00:02:23,380 So enter A to do. 37 00:02:24,860 --> 00:02:25,610 Clean. 38 00:02:27,310 --> 00:02:31,660 Again enter it to do through again meet. 39 00:02:33,880 --> 00:02:36,160 Free up Pluto. 40 00:02:37,750 --> 00:02:45,070 So we keep getting asked for to do over and over again, and this happens infinitely. 41 00:02:46,850 --> 00:02:48,080 Why does it happen? 42 00:02:48,080 --> 00:02:48,950 Infinitely? 43 00:02:48,980 --> 00:02:53,150 Well, because two is always greater than one. 44 00:02:54,580 --> 00:03:02,530 So the way the interpreter, the python interpreter is executing this script is this first it executes 45 00:03:02,530 --> 00:03:03,300 this line. 46 00:03:03,310 --> 00:03:11,530 It stores that enter a to do string to this variable and then it checks if two is greater than one. 47 00:03:11,740 --> 00:03:15,190 If it is, it executes this line. 48 00:03:17,960 --> 00:03:22,460 So we get that first prompt here and try to do. 49 00:03:24,410 --> 00:03:27,980 And then the interpreter looks if there are other lines down here. 50 00:03:28,280 --> 00:03:33,450 If not, it goes back to the wild loop to the first line. 51 00:03:33,470 --> 00:03:35,960 Again, it checks if two is greater than one. 52 00:03:35,960 --> 00:03:37,850 So it checks this condition. 53 00:03:37,850 --> 00:03:39,080 Two is greater than one. 54 00:03:39,080 --> 00:03:41,630 So it executes that line again. 55 00:03:42,110 --> 00:03:43,550 Enter A to do. 56 00:03:45,180 --> 00:03:48,660 To understand this better, you can stop the program. 57 00:03:51,140 --> 00:03:52,940 Use this button to stop it. 58 00:03:55,000 --> 00:03:58,810 And then you can print out the to do. 59 00:04:01,170 --> 00:04:02,550 And maybe print out. 60 00:04:04,850 --> 00:04:08,510 Next like that and execute. 61 00:04:08,510 --> 00:04:10,310 So enter it to do clean. 62 00:04:11,150 --> 00:04:19,670 So you see that Python executes this line first and then it prints out the to do that, the user enters 63 00:04:19,670 --> 00:04:26,870 it prints out next so that string and then it goes back again to the first line. 64 00:04:26,870 --> 00:04:29,150 It executes that line again. 65 00:04:29,690 --> 00:04:33,350 That's why this is called a loop. 66 00:04:33,560 --> 00:04:35,330 It's a while loop. 67 00:04:35,960 --> 00:04:40,940 We also have for loops, which is another type of loop, which we'll cover later on. 68 00:04:40,940 --> 00:04:44,930 We're going to need a for loop also as we develop the program. 69 00:04:45,970 --> 00:04:50,770 Before we close this video, I want to change something from this program. 70 00:04:53,010 --> 00:04:56,670 There is a simple way to write a condition. 71 00:04:56,670 --> 00:05:00,540 So instead of thinking, Oh, what is something that is true? 72 00:05:02,030 --> 00:05:06,440 Python has figured out a better way to just say true. 73 00:05:07,400 --> 00:05:10,160 So while true, execute this. 74 00:05:10,670 --> 00:05:11,330 So true. 75 00:05:11,330 --> 00:05:12,340 It's always true. 76 00:05:12,350 --> 00:05:14,840 Just like two is always greater than one. 77 00:05:14,840 --> 00:05:16,280 True is always true. 78 00:05:16,850 --> 00:05:18,860 So if I execute this program now. 79 00:05:20,220 --> 00:05:21,540 You can press that. 80 00:05:22,790 --> 00:05:24,380 To rerun the program. 81 00:05:26,290 --> 00:05:30,280 So now we are running the new script with through there. 82 00:05:30,700 --> 00:05:34,780 So enter clean and so you get asked for. 83 00:05:36,620 --> 00:05:39,410 To dos over and over again. 84 00:05:39,890 --> 00:05:41,360 So what is true? 85 00:05:41,390 --> 00:05:45,500 True is a Boolean is a data type. 86 00:05:46,370 --> 00:05:49,580 A Boolean is like strings and lists. 87 00:05:49,580 --> 00:05:52,010 So that was a string data type. 88 00:05:52,010 --> 00:05:53,660 This is a Boolean data type. 89 00:05:53,840 --> 00:05:58,460 And this here is a typical use of this data type. 90 00:05:58,460 --> 00:06:00,560 You can also have false here. 91 00:06:00,560 --> 00:06:01,730 False. 92 00:06:02,630 --> 00:06:06,050 But if we rerun the program. 93 00:06:07,040 --> 00:06:10,060 Nothing will happen because false is false. 94 00:06:10,070 --> 00:06:14,000 So none of these lines will be executed. 95 00:06:16,270 --> 00:06:22,180 Therefore, the end version is one to execute this. 96 00:06:23,590 --> 00:06:24,880 And that's about this video. 97 00:06:24,880 --> 00:06:30,280 So now the next step is to store these to dos in a list. 98 00:06:30,700 --> 00:06:31,870 How do we do that? 99 00:06:31,870 --> 00:06:33,430 I'll show you in the next video. 100 00:06:33,460 --> 00:06:33,730 See you.