WEBVTT 00:00.230 --> 00:07.580 Now, if you head over to task number three, in today's set of exercises, you'll see the code that 00:07.580 --> 00:09.500 we had from previously. 00:10.520 --> 00:14.240 And today I want to talk about a different function. 00:14.240 --> 00:21.830 So we've seen the print function and all the things that we can do to strings and use the print function 00:21.830 --> 00:23.180 and debug it. 00:23.180 --> 00:28.100 But what if we wanted to be able to enter some data. 00:28.130 --> 00:32.660 So if we wanted to say ask the user what is your name? 00:33.230 --> 00:40.550 And we run this code, you can see that being printed, but there's no way for the user on this side 00:40.550 --> 00:44.420 to be able to give our code some data to work with. 00:44.480 --> 00:51.080 In order to do that, instead of using the print function, we're going to use a different function, 00:51.080 --> 00:53.660 and it's called the input function. 00:53.660 --> 01:01.220 And notice how as I'm typing code, intelligence is already giving me some suggestions because it thinks 01:01.220 --> 01:03.740 it knows what I might want and it's right. 01:03.740 --> 01:07.140 So this is what the input function looks like. 01:07.170 --> 01:09.000 This is the name of the function. 01:09.000 --> 01:11.850 And again it's followed by some parentheses. 01:11.880 --> 01:16.410 Inside the parentheses is the prompt that I'm going to give the user. 01:16.440 --> 01:20.670 So when I run this code it will say what is your name. 01:20.940 --> 01:24.600 Now this time you'll notice a couple of differences. 01:24.600 --> 01:30.390 Firstly it doesn't have that final line process finished with exit code zero. 01:30.420 --> 01:33.270 It's actually not saying anything at all. 01:33.300 --> 01:39.330 Plus, when you look up here, you'll see that in addition to the play button, there's the stop button 01:39.330 --> 01:44.190 being highlighted and the play button has changed this rerun symbol. 01:44.220 --> 01:46.590 So what does all of this mean? 01:46.620 --> 01:52.560 Well, it means that we're actually in the middle of the process of running our code. 01:52.560 --> 01:54.510 It hasn't exited yet. 01:54.510 --> 01:56.850 And what exactly is it waiting for? 01:56.880 --> 02:04.200 Well, it's waiting for us to click into this output pane and actually type in an input. 02:04.230 --> 02:13.530 So the prompt is the text that goes into the input command, and then afterwards we can add some actual 02:13.530 --> 02:17.100 input, whatever it is we want into the output area. 02:17.100 --> 02:23.190 And now once I hit enter, you'll see that finally we have the process finished with exit code. 02:23.190 --> 02:29.820 You'll see the stop button is gone and we can now rerun the code as usual. 02:30.150 --> 02:35.730 But where did this text go and how can we capture it? 02:35.970 --> 02:42.600 The input function looks pretty much identical to the print function, but instead of the word print, 02:42.600 --> 02:46.980 it's just got the word input and inside the parentheses. 02:46.980 --> 02:54.150 Instead of adding what text will be printed, we're adding the prompt for the user to give them a hint 02:54.150 --> 02:56.010 as to what kind of data we want. 02:56.040 --> 03:02.190 And then when you run this code, it will print out the prompt, but then there will be a cursor. 03:02.190 --> 03:08.130 In some places you'll see it like a flashing cursor, other places it'll just be a solid cursor. 03:08.280 --> 03:15.310 And in some places you won't even see a cursor until you click into the output area ready for the user 03:15.310 --> 03:17.740 to type in some piece of data. 03:18.310 --> 03:20.890 So what can we do with this data? 03:20.980 --> 03:24.430 Well, we can use it inside our code. 03:24.970 --> 03:34.060 Now the way that this works is when this line is run by the computer, it takes your command as understanding 03:34.060 --> 03:35.980 that you want the user. 03:35.980 --> 03:45.400 So somebody to be able to you want the user to be able to type in an input into this area and whatever 03:45.400 --> 03:52.960 it is they type, you're going to take it back into the code and replace this command with it. 03:52.990 --> 03:56.650 So this is a little bit abstract when we see it like this. 03:56.650 --> 04:01.870 But let's imagine we wanted to write a print statement and we wanted to say hello. 04:01.870 --> 04:03.820 And we wanted to greet the user. 04:03.850 --> 04:07.300 Now I know that in my case my name is Angela. 04:07.300 --> 04:09.910 So I would get it to say hello Angela. 04:09.910 --> 04:13.150 But what if you didn't know the name of your user. 04:13.150 --> 04:17.290 Well, you wouldn't just want to say hello user or hello something generic. 04:17.320 --> 04:20.230 You would want them to be able to type in their name. 04:20.230 --> 04:25.270 So this is where a little bit of string concatenation comes in, which we learned before. 04:25.300 --> 04:33.910 If we take this input function that we've explored just now, and we paste it into this print statement. 04:34.180 --> 04:36.340 So this can be a little bit confusing. 04:36.340 --> 04:38.260 So just concentrate right here. 04:38.260 --> 04:40.540 There's two parentheses at the end. 04:40.540 --> 04:45.520 And the reason for this is because this first one closes off the print statement. 04:45.520 --> 04:48.310 So we're saying everything between here and here. 04:48.310 --> 04:50.110 We want it to be printed. 04:50.140 --> 04:52.000 Now what is in between there. 04:52.030 --> 04:59.650 Well firstly it's the string that says hello and then a space and then what we had as the input. 04:59.650 --> 05:04.840 So whatever the user types into here will replace this highlighted part. 05:04.840 --> 05:07.930 And we'll end up with hello concatenate. 05:07.930 --> 05:10.540 So add to another string. 05:10.540 --> 05:12.670 So let's try this out. 05:13.630 --> 05:20.330 Let's go ahead and hit run and you can see the prompt show up in the output area. 05:20.360 --> 05:27.920 So now if I click into this area, my cursor starts flashing and I can type whatever it is I want. 05:27.950 --> 05:35.210 Now when I hit enter, what I type is going to go and replace this input function. 05:35.210 --> 05:42.110 And then once it's in there, the print function is going to carry out its role and it's going to add 05:42.110 --> 05:43.580 the word hello in front of it. 05:43.580 --> 05:48.440 And then print it out right here so we can see now hello Angela. 05:48.440 --> 05:51.920 But this is of course making our code a lot more adaptable. 05:51.920 --> 05:58.400 So if tomorrow I decided to change my name to a cherry. 05:58.490 --> 06:00.770 There's a really embarrassing story about this. 06:00.770 --> 06:07.310 So when I first moved to the UK, I wanted to pick my own name because I was nine years old and I wanted 06:07.310 --> 06:11.540 a very, uh, fruit related name. 06:12.080 --> 06:15.590 Um, and this was the name that I wanted. 06:15.590 --> 06:20.810 And my parents, as, as wise as they are, said, no, we will take your name. 06:20.810 --> 06:23.630 So that's how I ended up with the name Angela. 06:23.990 --> 06:33.200 So now you can see this gets added in to the hello and we can have a completely adaptable bit of code. 06:33.530 --> 06:37.160 So now it's time for a small challenge. 06:37.160 --> 06:45.680 Can you use what you've learnt from previous lessons and also this lesson to figure out how to add a 06:45.680 --> 06:51.080 exclamation mark to the end of the sentence that's being printed. 06:51.080 --> 06:55.880 So instead of just hello Angela, we want the output to say hello. 06:55.880 --> 07:00.350 And then we take in whatever it is the user inputs into here. 07:00.350 --> 07:03.500 And then we replace that with the user input. 07:03.500 --> 07:06.290 And finally we add an exclamation mark. 07:06.290 --> 07:11.720 Now of course we have to do this using strings and using what we've learned about Python code. 07:11.720 --> 07:17.240 So pause the video, read the description of the problem and see if you can solve it. 07:17.240 --> 07:20.610 Okay, so if you remember from string Catenation. 07:20.610 --> 07:28.980 What we need to do is we need to treat this input function as its own string, because eventually it's 07:28.980 --> 07:30.570 going to be replaced by a string. 07:30.570 --> 07:37.920 So we can take that part, set it aside, and then we can use the plus sign to concatenate the final 07:37.920 --> 07:44.160 character, which is a exclamation mark to this entire long string. 07:44.160 --> 07:52.020 So now if I go ahead and run this code and I type in an input, that input gets inserted and replaces 07:52.020 --> 07:54.030 this entire input function. 07:54.030 --> 07:58.530 And then finally I get the exclamation mark added to the end. 07:58.800 --> 08:05.040 If you find this line of code difficult to understand and to wrap your head around, then I recommend 08:05.070 --> 08:06.960 heading over to a website called thonny. 08:07.170 --> 08:10.440 Org and downloading an application called Thonny. 08:10.470 --> 08:14.250 It's completely free and it's available for windows, Mac and Linux. 08:14.250 --> 08:22.200 And once you've installed this application, you can go ahead and paste your line of code here and click 08:22.200 --> 08:24.340 on this little debug symbol. 08:24.490 --> 08:31.120 And then we can click on this button which is called the step into button, to step into the execution 08:31.120 --> 08:37.690 of this line of code to see how the computer is evaluating this code here step by step. 08:37.720 --> 08:42.340 So you'll see the first thing it tries to do is it will try to run this print statement. 08:42.340 --> 08:46.060 It looks inside these parentheses to see what it needs to print. 08:46.060 --> 08:48.790 So the first thing is this hello. 08:48.790 --> 08:51.190 And it turns that into a string. 08:51.310 --> 08:56.650 And then it looks at the next thing after the plus sign to see what it should turn this into. 08:56.680 --> 08:58.870 And this of course is the input function. 08:58.870 --> 09:03.520 So as I continue stepping into it it's actually going to execute it. 09:03.520 --> 09:07.270 So it's going to run this input function and show the prompt. 09:07.270 --> 09:08.560 What is your name. 09:08.950 --> 09:10.960 So that's what shows up down here. 09:10.960 --> 09:19.750 And now if I enter a value in here and hit enter, then that value that I put right there replaces that 09:19.810 --> 09:24.430 previous input function and is now held inside the print statement. 09:24.430 --> 09:27.790 So if I continue stepping through this code. 09:27.790 --> 09:31.300 Then you'll see it concatenates all of the pieces together. 09:31.300 --> 09:34.540 And finally it just ends up with a simple print. 09:34.570 --> 09:35.530 Hello, Angela! 09:35.560 --> 09:36.760 Exclamation mark. 09:36.760 --> 09:43.210 And if I continue stepping into it, you'll see that line of code executed until there are no more instructions 09:43.210 --> 09:43.840 left. 09:43.840 --> 09:50.110 So if you prefer seeing your code, um, run like this step by step so that you can see what's going 09:50.110 --> 09:52.660 on, then I recommend giving this a go. 09:53.500 --> 09:57.490 As you're learning to code, there's going to be new concepts covered. 09:57.520 --> 10:01.990 There's going to be things that take a little bit of thinking before you can understand it. 10:01.990 --> 10:07.450 So what a lot of programmers love to do is they like to comment in their code. 10:07.480 --> 10:12.730 Now, you might have seen this already throughout the coding exercises and the solutions I provided, 10:12.730 --> 10:21.070 but in Python, if you wanted a line of text to not be considered by the computer at all, all you have 10:21.070 --> 10:29.900 to do is add the hashtag or pound sign in front of your text, and this turns it into a comment. 10:29.900 --> 10:33.440 So something that the computer will completely ignore. 10:33.440 --> 10:39.020 So in here you can write code as much as you like, but it won't be executed. 10:39.020 --> 10:43.100 And when you click run, you'll see that this is completely ignored. 10:43.130 --> 10:49.460 What I recommend is whenever you come across a new concept in the course, to make a comment above it 10:49.460 --> 10:55.760 so that you can explain to yourself what's actually going on in the line of code below. 10:56.150 --> 11:01.430 This way, the next time you come across this line of code and you're not quite sure what's actually 11:01.430 --> 11:06.740 happening here, you can have a look at the notes that you've written for yourself in your own words, 11:06.740 --> 11:11.990 and hopefully it'll jog your memory and make it much easier to comprehend what's going on. 11:13.010 --> 11:21.290 In addition to adding a pound sign manually, you can also highlight a line of code or simply have your 11:21.290 --> 11:26.180 cursor on a line of code and hold down command and forward slash. 11:26.180 --> 11:30.950 If you're on Mac or Control and forward slash if you're on windows. 11:30.950 --> 11:38.120 And what this does is it takes this line of code out of the computer's awareness, and it's no longer 11:38.120 --> 11:40.700 executed when you run this code file. 11:40.700 --> 11:46.880 So the process is finished without anything being carried out at all, because all the computer is seeing 11:46.880 --> 11:52.340 is a blank page, because we've taken all the code out into comments. 11:52.370 --> 11:58.160 So in order to take this back into code, all you have to do is use the same command that you tried 11:58.160 --> 11:58.760 just now. 11:58.760 --> 12:03.530 So command forward slash on Mac or control forward slash on windows. 12:03.530 --> 12:08.090 And this will now again be considered as code by the computer. 12:08.720 --> 12:09.530 All right. 12:09.530 --> 12:12.920 So in this lesson we learned about the input function. 12:12.920 --> 12:19.610 We learned about putting functions inside other functions and being able to get user input from the 12:19.610 --> 12:22.490 console by using the input function. 12:22.520 --> 12:29.180 And if you've commented this line of code thoroughly and you've fully understood how it works, then 12:29.210 --> 12:32.120 you'll be able to breeze through the next exercise. 12:32.120 --> 12:35.210 So for all of that and more, I'll see you there.