1 00:00:00,270 --> 00:00:02,550 Coming back to our Repl.it, 2 00:00:02,760 --> 00:00:07,230 the Day 1 printing repl that you should have from previously, 3 00:00:08,039 --> 00:00:10,410 I want to talk about a different function. 4 00:00:10,530 --> 00:00:15,530 So we've seen the print function and all the things that we can do to strings 5 00:00:15,870 --> 00:00:19,230 and use the print function and debug it. 6 00:00:19,710 --> 00:00:24,090 But what if we wanted to be able to enter some data? 7 00:00:24,630 --> 00:00:26,220 So if we wanted to say, 8 00:00:26,220 --> 00:00:31,020 ask the user 'what is your name?' And we run this code, 9 00:00:31,410 --> 00:00:33,180 you can see that being printed, 10 00:00:33,570 --> 00:00:38,570 but there's no way for the user on this side to be able to give our code some 11 00:00:39,150 --> 00:00:42,270 data to work with. In order to do that, 12 00:00:42,630 --> 00:00:44,970 instead of using the print function, 13 00:00:45,270 --> 00:00:49,500 we're going to use a different function and it's called the input function. 14 00:00:50,250 --> 00:00:52,470 And notice how as I'm typing, 15 00:00:52,710 --> 00:00:57,570 code intelligence is already giving me some suggestions because it thinks it 16 00:00:57,570 --> 00:00:59,670 knows what I might want and it's right. 17 00:01:00,180 --> 00:01:05,069 So this is what the input function looks like. This is the name of the function. 18 00:01:05,459 --> 00:01:09,300 And again, it's followed by some parentheses. Inside the parentheses 19 00:01:09,300 --> 00:01:12,270 is the prompt that I'm going to give the user. 20 00:01:12,990 --> 00:01:16,590 So when I run this code, it will say, what is your name? 21 00:01:17,100 --> 00:01:22,100 And then the cursor will stay at the end of this line because it's expecting 22 00:01:22,950 --> 00:01:27,300 some sort of input. If I give it my name, Angela and I hit enter, 23 00:01:27,720 --> 00:01:32,720 then this piece of data has now been passed back into my code and it now 24 00:01:33,600 --> 00:01:36,360 replaces this part of the code. 25 00:01:36,780 --> 00:01:39,180 So I'm passing data from over here, 26 00:01:39,540 --> 00:01:42,480 back to over here where I can use it in my code. 27 00:01:43,680 --> 00:01:46,890 Now notice the difference here. It looks quite similar. 28 00:01:47,100 --> 00:01:50,940 When we run print, you can see it says what is your name? 29 00:01:51,390 --> 00:01:56,190 and then the code execution ends and we know it ends because it's showing us 30 00:01:56,220 --> 00:01:57,720 this little orange arrow. 31 00:01:58,350 --> 00:02:01,290 But notice when I run input instead, 32 00:02:01,830 --> 00:02:03,570 I don't see the orange arrow. 33 00:02:03,750 --> 00:02:08,750 My program is actually paused right now in order for the user to provide an 34 00:02:09,060 --> 00:02:13,200 input and it's only when I've given the input and hit enter 35 00:02:13,680 --> 00:02:15,090 does the program end. 36 00:02:15,630 --> 00:02:19,890 The input function looks pretty much identical to the print function, 37 00:02:20,280 --> 00:02:21,990 but instead of the word print, 38 00:02:22,080 --> 00:02:26,220 it's just got the word input. And inside the parentheses, 39 00:02:26,460 --> 00:02:29,460 instead of adding what text will be printed, 40 00:02:29,760 --> 00:02:34,620 we're adding the prompt for the user to give them a hint as to what kind of data 41 00:02:34,620 --> 00:02:38,970 we want. And then when you run this code, it will print out the prompt, 42 00:02:39,240 --> 00:02:43,860 but then there will be a cursor. In some places you'll see it like a flashing 43 00:02:43,860 --> 00:02:45,390 cursor, other places, 44 00:02:45,420 --> 00:02:50,420 it'll just be a solid cursor ready for the user to type in some piece of data. 45 00:02:51,630 --> 00:02:54,960 So what can we do with this data? Well, 46 00:02:54,960 --> 00:02:57,450 we can use it inside our code. 47 00:02:58,140 --> 00:03:03,140 Remember how I said once this line of code executes and I've entered Angela as 48 00:03:03,700 --> 00:03:05,200 the response to this input, 49 00:03:05,650 --> 00:03:10,420 then this part of the code gets replaced by whatever it is that the user typed 50 00:03:10,420 --> 00:03:13,000 in. So in this case it becomes Angela. 51 00:03:13,840 --> 00:03:18,840 And what I can do with it is let's say I wanted to print something like, 52 00:03:19,450 --> 00:03:23,470 hello Angela. Well, 53 00:03:23,470 --> 00:03:28,470 then I can simply write Hello + input and then I'm going to close it off 54 00:03:32,440 --> 00:03:34,120 with another set of brackets. 55 00:03:34,990 --> 00:03:37,990 So I'm going to change my layout instead of side by side, 56 00:03:38,020 --> 00:03:39,880 I'm going to change it to stacked. 57 00:03:40,360 --> 00:03:43,870 And this means that I've got my code at the top and my console at the bottom. 58 00:03:44,230 --> 00:03:47,530 This way my line can go a little bit longer without it rapping. 59 00:03:48,190 --> 00:03:49,750 Notice what's happening here. 60 00:03:50,800 --> 00:03:55,800 This is the input function that I showed you earlier on and this is a print 61 00:03:56,020 --> 00:03:56,853 statement. 62 00:03:56,890 --> 00:04:01,890 So we've got this nested inside the other. And now when I run my code, 63 00:04:03,940 --> 00:04:07,240 what happens is it asked me what is your name? 64 00:04:07,420 --> 00:04:10,660 So I'll write my name and then when I hit enter, 65 00:04:11,230 --> 00:04:16,230 this part is replaced by Angela and it gets concatenated to the word hello and 66 00:04:18,790 --> 00:04:21,130 the entire thing gets printed out down here. 67 00:04:21,880 --> 00:04:25,990 If you find this line of code difficult to understand and to wrap your head 68 00:04:25,990 --> 00:04:26,823 around, 69 00:04:26,890 --> 00:04:31,890 then I recommend heading over to a website called thonny.org and downloading an 70 00:04:31,990 --> 00:04:35,980 application called Thonny. It's completely free and it's available for Windows, 71 00:04:35,980 --> 00:04:40,180 Mac, and Linux. And once you've installed this application, 72 00:04:40,540 --> 00:04:45,540 you can go ahead and paste your line of code here and click on this little debug 73 00:04:46,570 --> 00:04:49,750 symbol. And then we can click on this button, 74 00:04:49,840 --> 00:04:54,760 which is called the step into button to step into the execution of this line of 75 00:04:54,760 --> 00:04:55,420 code 76 00:04:55,420 --> 00:05:00,420 to see how the computer is evaluating this code here step by step. 77 00:05:01,090 --> 00:05:04,870 So you'll see the first thing it tries to do is it will try to run this print 78 00:05:04,870 --> 00:05:08,800 statement. It looks inside, these parentheses to see what it needs to print. 79 00:05:09,370 --> 00:05:11,680 So the first thing is this, Hello, 80 00:05:12,100 --> 00:05:17,020 and it turns that into a string and then it looks at the next thing after the 81 00:05:17,020 --> 00:05:19,510 plus sign to see what it should turn this into. 82 00:05:19,930 --> 00:05:24,160 And this of course is the input function. So as I continue stepping into it, 83 00:05:24,520 --> 00:05:26,410 it's actually going to execute it. 84 00:05:26,740 --> 00:05:31,360 So it's going to run this input function and show the prompt, what is your name? 85 00:05:32,050 --> 00:05:33,760 So that's what shows up down here. 86 00:05:34,300 --> 00:05:37,600 And now if I enter a value in here and hit enter, 87 00:05:38,020 --> 00:05:43,020 then that value that I put right there replaces that previous input function 88 00:05:44,800 --> 00:05:47,200 and is now held inside the print statement. 89 00:05:47,740 --> 00:05:52,740 So if I continue stepping through this code then you'll see it concatenates all of 90 00:05:53,320 --> 00:05:57,590 the pieces together, and finally it just ends up with a simple print 91 00:05:57,680 --> 00:06:01,760 Hello Angela! And if I continue stepping into it, 92 00:06:01,820 --> 00:06:06,620 you'll see that line of code executed until there are no more instructions left. 93 00:06:07,160 --> 00:06:10,040 So if you prefer seeing your code, um, 94 00:06:10,070 --> 00:06:13,490 run like this step by step so that you can see what's going on, 95 00:06:13,760 --> 00:06:15,500 then I recommend giving this a go. 96 00:06:16,580 --> 00:06:21,110 But because of how easy it is to share these Repl.it code bases so that we're 97 00:06:21,110 --> 00:06:24,950 working from the same place, I recommend to do most of your coding here 98 00:06:25,130 --> 00:06:30,130 and only if you get stuck to take a single line of code and paste it into Thonny 99 00:06:30,740 --> 00:06:35,630 to see how it's executed step-by-step. As you're learning to code, 100 00:06:35,690 --> 00:06:37,880 there's going to be new concepts covered. 101 00:06:38,090 --> 00:06:41,300 There's going to be things that take a little bit of thinking before you can 102 00:06:41,300 --> 00:06:42,230 understand it. 103 00:06:42,740 --> 00:06:47,740 So what a lot of programmers love to do is they like to comment in their code. 104 00:06:48,200 --> 00:06:48,410 Now, 105 00:06:48,410 --> 00:06:52,210 you might've seen this already throughout the coding exercises and the solutions 106 00:06:52,230 --> 00:06:54,740 I provided. But in Python, 107 00:06:55,280 --> 00:07:00,280 if you wanted a line of text to not be considered by the computer at all, 108 00:07:01,010 --> 00:07:06,010 all you have to do is add the hashtag or pound sign in front of your text and 109 00:07:08,030 --> 00:07:10,370 this turns it into a comment, 110 00:07:10,580 --> 00:07:13,730 so something that the computer will completely ignore. 111 00:07:14,180 --> 00:07:17,840 So in here you can write code as much as you like, um, 112 00:07:17,870 --> 00:07:20,840 but it won't be executed and when you click run, 113 00:07:21,050 --> 00:07:23,270 you'll see that this is completely ignored. 114 00:07:23,960 --> 00:07:28,430 What I recommend is whenever you come across a new concept in the course to make 115 00:07:28,430 --> 00:07:33,430 a comment above it so that you can explain to yourself what's actually going on 116 00:07:34,370 --> 00:07:37,610 in the line of code below. This way 117 00:07:37,640 --> 00:07:41,630 the next time you come across this line of code and you're not quite sure what's 118 00:07:41,630 --> 00:07:42,710 actually happening here, 119 00:07:43,040 --> 00:07:46,730 you can have a look at the notes that you've written for yourself in your own 120 00:07:46,730 --> 00:07:51,050 words and hopefully it'll re-jog your memory and make it much easier to 121 00:07:51,050 --> 00:07:52,280 comprehend what's going on. 122 00:07:53,720 --> 00:07:58,010 In addition to adding a pound sign manually, 123 00:07:58,160 --> 00:08:03,080 you can also highlight a line of code or simply have your cursor on a line of 124 00:08:03,080 --> 00:08:08,080 code and hold down command and forward slash if you're on Mac or control and 125 00:08:09,290 --> 00:08:11,270 forward slash if you're on Windows. 126 00:08:11,630 --> 00:08:14,240 And if you want to go back or undo your changes, 127 00:08:14,540 --> 00:08:19,160 it's simply command +z or control + z. All right, 128 00:08:19,310 --> 00:08:22,490 so in this lesson we learned about input function, 129 00:08:22,760 --> 00:08:27,680 we learned about putting functions inside other functions and being able to get 130 00:08:27,980 --> 00:08:31,790 user input from the console by using the input function. 131 00:08:32,330 --> 00:08:36,020 So now I've got a coding exercise for you in the next lesson, 132 00:08:36,559 --> 00:08:41,210 and if you've commented this line of code thoroughly and you fully understood 133 00:08:41,419 --> 00:08:45,470 how it works, then you'll be able to breeze through the next exercise. 134 00:08:46,010 --> 00:08:48,650 So for all of that and more, I'll see you there.