1 00:00:00,009 --> 00:00:00,490 All right. 2 00:00:00,500 --> 00:00:05,739 So welcome to this brand new section where we're going to take a look at functions 3 00:00:06,039 --> 00:00:07,829 and so far so good. 4 00:00:08,029 --> 00:00:09,649 We've actually been working with quite a 5 00:00:09,659 --> 00:00:12,989 number of prebuilt functions within Python. 6 00:00:13,220 --> 00:00:17,690 So functions like the print input range and so on, 7 00:00:17,840 --> 00:00:21,639 they all perform a particular kind of operation. 8 00:00:22,000 --> 00:00:26,709 However, what if we wanted to create our very own custom functions? 9 00:00:26,719 --> 00:00:28,989 How can we do that well to do? So 10 00:00:29,200 --> 00:00:31,379 we are going to have to 11 00:00:31,569 --> 00:00:34,860 define the name of the function first of all 12 00:00:35,270 --> 00:00:37,009 and then decide whether or not that function 13 00:00:37,020 --> 00:00:40,180 is going to accept what we call parameters. 14 00:00:40,669 --> 00:00:42,099 And then we can also say, OK, 15 00:00:42,110 --> 00:00:46,000 this function will add these numbers or is going to do something. 16 00:00:46,250 --> 00:00:51,860 And then finally, we can choose to return a value within that function. So 17 00:00:52,119 --> 00:00:53,349 it's going to be something like this. OK? 18 00:00:53,360 --> 00:00:57,900 You will have the def which is going to be the function to define 19 00:00:58,310 --> 00:01:03,049 the name of the function. And then you can, you can choose to have parameters 20 00:01:03,380 --> 00:01:05,440 inside of that function. 21 00:01:05,910 --> 00:01:06,529 OK? 22 00:01:06,839 --> 00:01:07,569 And then 23 00:01:07,680 --> 00:01:10,209 we'll have the function body. 24 00:01:10,220 --> 00:01:14,029 So you know, add A plus B, add this, 25 00:01:14,040 --> 00:01:17,430 do this divide this check to see if this loop is true, you know, stuff like that, 26 00:01:17,440 --> 00:01:19,430 basically whatever the, the function will do. 27 00:01:19,690 --> 00:01:20,730 And then finally, 28 00:01:21,480 --> 00:01:23,180 we can then choose to return 29 00:01:23,750 --> 00:01:25,940 a value, which by the way, 30 00:01:26,349 --> 00:01:29,300 this is going to be optional, 31 00:01:29,680 --> 00:01:35,690 we don't always have to return a value whenever we are creating our own function. 32 00:01:35,760 --> 00:01:37,660 Let me give you a very, very basic example. 33 00:01:37,669 --> 00:01:39,400 So let's say for example, we wanted to create 34 00:01:39,620 --> 00:01:40,690 a function 35 00:01:40,949 --> 00:01:42,059 that will print 36 00:01:42,389 --> 00:01:44,620 the words hello world. 37 00:01:44,860 --> 00:01:45,500 All right, 38 00:01:46,160 --> 00:01:50,139 we can say DF and then I can call my function greet. 39 00:01:50,500 --> 00:01:52,230 So the name of my function is going to be 40 00:01:52,239 --> 00:01:56,480 greet and then I can add my brackets at the colon 41 00:01:56,970 --> 00:01:57,849 and then enter, 42 00:01:58,349 --> 00:02:03,220 by the way, notice that I haven't added any parameters inside of the 43 00:02:03,339 --> 00:02:04,690 brackets in here. 44 00:02:04,900 --> 00:02:06,360 Parameters are optional. 45 00:02:07,230 --> 00:02:08,020 However, 46 00:02:08,110 --> 00:02:11,740 I'm gonna come in right now and then define what the function will actually do. 47 00:02:11,750 --> 00:02:13,210 So I'm gonna say print. 48 00:02:14,270 --> 00:02:15,039 Now, 49 00:02:15,250 --> 00:02:18,789 I'm going to provide the words hello 50 00:02:19,190 --> 00:02:20,130 world. 51 00:02:21,220 --> 00:02:23,220 And now all I would have to do 52 00:02:23,460 --> 00:02:26,479 is to simply call the function. 53 00:02:26,800 --> 00:02:28,940 And how do I do that? I'm gonna say greet 54 00:02:29,449 --> 00:02:30,649 and then the packets. 55 00:02:31,210 --> 00:02:32,000 And if it is, 56 00:02:32,729 --> 00:02:36,070 so now if I was to run the program, there you go. 57 00:02:36,220 --> 00:02:38,759 It simply says hello world. 58 00:02:39,179 --> 00:02:43,130 So once again, we started off by giving the name 59 00:02:43,389 --> 00:02:45,630 greet to our function. 60 00:02:46,429 --> 00:02:48,929 And then we're now told what the function should do. 61 00:02:48,940 --> 00:02:54,910 The function should print Hello world. Whenever we call or use that function. 62 00:02:55,029 --> 00:02:57,600 And then right here we simply call the 63 00:02:57,610 --> 00:02:59,970 function by simply saying greet and then in brackets 64 00:03:00,220 --> 00:03:00,770 and 65 00:03:00,949 --> 00:03:02,610 there you go. 66 00:03:02,779 --> 00:03:04,690 So this right here is 67 00:03:04,899 --> 00:03:08,940 one of the most basic kinds of functions we can create. 68 00:03:09,289 --> 00:03:10,229 But that's it, German. 69 00:03:10,270 --> 00:03:14,050 Even next video where we'll now begin to take a look at function parameters 70 00:03:14,220 --> 00:03:15,770 and arguments. I'll see you then.