WEBVTT 0 00:00.170 --> 00:07.010 In the last lesson, we saw a very simple form of a function that allows for an input. 1 00:07.040 --> 00:13.190 Now in this lesson, I want to take it even further, and I want to create a function that allows for 2 00:13.190 --> 00:14.780 multiple inputs. 3 00:15.140 --> 00:19.520 So let's comment out the previous line of code and let's create a new comment. 4 00:19.520 --> 00:21.740 Functions with more than one input. 5 00:22.610 --> 00:27.590 And I'm going to create a new function called greet_with(). 6 00:27.620 --> 00:31.760 And in this case it's going to take two parameters, 7 00:31.760 --> 00:35.480 it's going to be name and location. 8 00:35.480 --> 00:39.440 If you remember this is how we added a parameter previously. 9 00:39.440 --> 00:46.220 Now as a challenge, I want you to quickly think about how you might add two parameters, one called name 10 00:46.220 --> 00:50.450 and one called location into this function declaration. 11 00:50.450 --> 00:53.880 Pause the video, have a brief think and then we'll go through it together. 12 00:54.900 --> 00:55.380 All right. 13 00:55.380 --> 00:59.940 So we know that if we wanted to add one parameter name then this is how we would do it. 14 00:59.940 --> 01:02.970 We would just add it inside the parentheses. 15 01:03.180 --> 01:10.080 Now if we want to have more than one parameter, all we have to do is just add a comma and then add 16 01:10.080 --> 01:13.980 the second parameter, which we said was going to be called location. 17 01:13.980 --> 01:20.100 So now this particular function is going to take two inputs the name and the location. 18 01:20.100 --> 01:27.390 And then inside this function, we're going to use the name to print something like, "Hello name." 19 01:27.660 --> 01:34.830 And then we're going to print and ask them what is it like in their particular location. 20 01:35.160 --> 01:40.650 See if you can modify this to use the actual parameters and to replace them with print statements, 21 01:40.650 --> 01:44.920 so that we use these parameters inside our function. 22 01:44.950 --> 01:46.930 Pause the video now and give that a go. 23 01:48.100 --> 01:48.610 All right. 24 01:48.610 --> 01:51.670 So essentially, we want to create a print statement here, 25 01:51.670 --> 01:54.340 and print statements print strings. 26 01:54.340 --> 01:57.550 So we have to add some quotation marks around that text. 27 01:57.550 --> 02:07.120 And then finally, I'm going to use an f-string to replace this parameter name inside this string so that 28 02:07.120 --> 02:13.450 the data that gets passed in gets replaced here, and it says "Hello..." whatever their name is. 29 02:13.450 --> 02:16.540 And then I'm just going to do the same thing over here. 30 02:19.840 --> 02:26.050 And notice that you can simply highlight a word, or highlight a sentence, and then use the open curly 31 02:26.050 --> 02:31.160 brace to actually add the brace around both sides of the word. 32 02:31.160 --> 02:34.880 And you'll notice that I did the same thing with the quotation mark. 33 02:34.880 --> 02:38.390 So highlight the whole sentence, and then hit the double quote key, 34 02:38.390 --> 02:42.830 and it will keep adding quotes around both sides of your highlight. 35 02:43.520 --> 02:45.590 But I only actually need one. 36 02:45.590 --> 02:49.310 So that is our function completed. 37 02:49.310 --> 02:55.550 And now it means that I can call this function by calling greet_with() and it's going to prompt me to 38 02:55.550 --> 02:58.220 add both of these inputs. 39 02:58.220 --> 03:02.240 And the first piece of data is going to be the name, 40 03:02.240 --> 03:04.850 and let's put Jack Bauer. 41 03:05.990 --> 03:11.000 And then we can add the second piece of data and separate it with a comma. 42 03:11.000 --> 03:13.790 So let's say that Jack Bauer is nowhere. 43 03:14.270 --> 03:20.540 Now if we go ahead and run this code then you'll see that it's going to print "Hello" and replace name 44 03:20.540 --> 03:21.650 with "Jack Bauer", 45 03:21.650 --> 03:24.440 and then, "What is it like in Nowhere" 46 03:24.440 --> 03:27.380 So Nowhere gets replaced with this location. 47 03:27.380 --> 03:34.910 So that means that you can now put in as many pieces of inputs as you want, and modify the functionality 48 03:34.910 --> 03:40.310 of your function to make your function do different things each time. 49 03:41.330 --> 03:47.830 Now here's a question what happens if I call the same function greet_with(), 50 03:47.830 --> 03:51.940 but I switch the order of the data that I give it. 51 03:51.940 --> 03:55.750 So let's say the first piece of data I give it is "Nowhere," 52 03:55.960 --> 04:00.160 and then the second piece of data is "Jack Bauer". 53 04:00.160 --> 04:03.820 So we've just switched the order of these pieces of data. 54 04:03.910 --> 04:06.460 Now what do you expect to happen? 55 04:06.460 --> 04:12.120 Pause for a moment and have a think about what you expect to be printed in here and then continue. 56 04:13.590 --> 04:14.070 All right. 57 04:14.070 --> 04:19.800 So let's click run and you can see that it's now complete nonsense. 58 04:19.800 --> 04:20.160 "Hello 59 04:20.160 --> 04:20.730 Nowhere 60 04:20.730 --> 04:22.350 What is it like in Jack Bauer." 61 04:22.350 --> 04:29.460 And what's actually happened here is it takes the position of the data, looks at both of these arguments, 62 04:29.460 --> 04:32.740 and the first argument gets assigned to the first parameter, 63 04:32.770 --> 04:35.740 the second argument gets assigned to the second parameter. 64 04:35.770 --> 04:42.040 So in this case, when it's actually gone in here name is now equal to "Nowhere," which is why this line 65 04:42.040 --> 04:43.000 printed this, 66 04:43.000 --> 04:49.180 and "Jack Bauer" is now assigned to location, which is why it printed the second line like so. 67 04:49.900 --> 04:56.770 And in Python programming, this is called a Positional Argument, because when we call the function, 68 04:56.770 --> 05:04.300 we haven't specified anywhere which particular parameter we want to associate these pieces of data with. 69 05:04.300 --> 05:06.940 So it's just gone and looked at the position. 70 05:06.940 --> 05:12.280 Now this is the default way of calling functions, because on one hand, when you're typing out the 71 05:12.280 --> 05:17.200 code, you get the hints here as to which piece of data you need to enter. 72 05:17.200 --> 05:22.610 But also you can refer to the function and look at the order of the parameters. 73 05:23.210 --> 05:31.310 Even if we had more inputs, let's say in this case we had a, b and c, and we put the argument 1, 74 05:31.310 --> 05:32.510 2 and 3, 75 05:32.510 --> 05:41.360 Then it means that our variables that gets created will be a = 1, b = 2, and c = 3 76 05:41.360 --> 05:42.140 . 77 05:43.940 --> 05:48.920 Now if we switch around the order of the arguments in the function call, 78 05:48.920 --> 05:53.570 now what will happen is a is going to be equal to the first argument. 79 05:53.570 --> 05:59.870 So a is now equal to three, b is equal to the second argument, and c is equal to the third argument. 80 05:59.870 --> 06:03.740 So it might be doing slightly unpredictable things in here. 81 06:03.740 --> 06:09.020 So whenever you're creating code and you're using these positional arguments and you're just inserting 82 06:09.020 --> 06:13.280 the data one by one like this, and it does something completely unexpected, 83 06:13.280 --> 06:20.030 then be sure to check your positioning and to make sure that it matches with the position of the parameters. 84 06:21.140 --> 06:27.980 Now what if you wanted to be more clear when you actually call the function so you don't ever encounter 85 06:27.980 --> 06:29.030 this problem? 86 06:29.150 --> 06:33.230 Well, you could use something called Keyword Arguments instead. 87 06:33.230 --> 06:40.290 So now instead of just adding the arguments into the function call like this, we can actually add each 88 06:40.290 --> 06:46.590 of the parameter names and an equal sign to say that the first parameter a = 1, 89 06:46.590 --> 06:49.980 b = 2, and c = 3. 90 06:49.980 --> 06:56.250 And now when we actually change the order around, it doesn't matter how we order it, it's still going 91 06:56.250 --> 06:58.630 to abide by these bindings. 92 06:58.630 --> 07:02.410 So c will still be 3and a will still be 1. 93 07:03.700 --> 07:09.760 As a challenge, I want you to take this previous function, greet_with() name and location, 94 07:09.760 --> 07:13.090 and I want you to call this function down here, 95 07:13.090 --> 07:18.910 but this time, instead of using positional arguments I want you to use keyword arguments. 96 07:18.910 --> 07:22.030 So pause the video and try and give that a go. 97 07:24.580 --> 07:25.120 All right. 98 07:25.120 --> 07:27.640 So when we call the function we still use the name. 99 07:27.640 --> 07:28.900 So it's greet_with(). 100 07:28.900 --> 07:31.870 So everything up to the first parentheses is the name. 101 07:31.870 --> 07:36.010 And then we add in each of these parameter names, 102 07:36.010 --> 07:38.410 and then we add an equal sign, 103 07:38.410 --> 07:41.200 and finally we give it the actual value. 104 07:41.200 --> 07:42.640 So let's say, "Angela". 105 07:42.640 --> 07:47.980 And then the location is going to be equal to "London". 106 07:48.550 --> 07:52.600 Now, when I hit Run, you can see it does pretty much the same as before, 107 07:52.600 --> 07:55.930 it puts Angela into name, London into location. 108 07:55.930 --> 08:00.400 But this time if I switch the order around, it no longer matters. 109 08:00.400 --> 08:06.970 And when I hit Run again, you can see it does exactly the same thing, because it now knows which argument 110 08:06.970 --> 08:09.730 is associated with which parameter. 111 08:10.120 --> 08:15.470 So this can make your code less error-prone, but it does make each line of code longer. 112 08:15.500 --> 08:22.550 I recommend using your judgement to figure out when you want to use which type of argument, and depending 113 08:22.550 --> 08:24.890 on the need, you can pick between these two. 114 08:25.910 --> 08:32.120 Now in the next lesson, I've got a coding exercise for you to put into practice everything that you've 115 08:32.120 --> 08:33.230 learned so far. 116 08:33.260 --> 08:36.290 Head over there when you're ready and let's give it a go.