WEBVTT 00:01.120 --> 00:08.040 After all, you learn about loops, conditions, casting, data type variable, and a lot of things. 00:08.280 --> 00:13.440 Now it is time for learning something about functions. 00:13.480 --> 00:24.800 Okay, first let's create a punk.py file and we are going to learn function examples and everything 00:24.800 --> 00:25.080 here. 00:25.120 --> 00:25.760 Okay. 00:25.800 --> 00:26.840 What is a function. 00:27.000 --> 00:32.040 A function is a block of code which only runs when it is called. 00:32.080 --> 00:32.680 Okay. 00:32.720 --> 00:36.840 You can pass data known as parameter into a function. 00:37.240 --> 00:41.240 And also a function can return data as a result. 00:41.280 --> 00:44.520 Okay, so how can we create a function. 00:45.000 --> 00:45.920 Okay. 00:46.000 --> 00:48.400 Actually we have two kind of function okay. 00:48.440 --> 00:51.040 One of them is built in function. 00:51.040 --> 00:55.360 And also pre the function that you can define it okay. 00:55.400 --> 01:01.920 So in Python a function is defined using a def keyword or def like this. 01:02.910 --> 01:05.150 And let's create a function. 01:05.150 --> 01:06.710 Name it my function. 01:07.270 --> 01:11.870 And like this you can create a function like this. 01:11.910 --> 01:15.630 Okay you use diff keyword and then you give a name to the function. 01:15.630 --> 01:20.510 And this use this parenthesis and use colon head enter. 01:20.510 --> 01:28.790 And right here for example let's print a text here and say hello from a function. 01:29.470 --> 01:30.270 Very easy. 01:30.550 --> 01:31.390 Okay. 01:31.390 --> 01:35.510 Now if I run this it will do nothing and I will tell you why. 01:36.390 --> 01:40.190 Let's use Python function.py. 01:40.190 --> 01:43.230 And you see that we have no output. 01:44.190 --> 01:44.550 Why? 01:45.030 --> 01:47.870 Because we haven't called this. 01:48.230 --> 01:57.630 Okay, I told you, function can be run and can be executed whenever it is called only it is if it is 01:57.630 --> 01:59.910 called so it will be executed. 01:59.910 --> 02:03.030 If not, it is not going to be executed. 02:03.510 --> 02:08.830 So to call a function, use the use the function name followed by parentheses. 02:09.310 --> 02:18.710 So here let's use my function and then use these parentheses. 02:19.110 --> 02:22.750 Now let's save it and then run it again. 02:23.070 --> 02:24.790 You see now we have it. 02:24.830 --> 02:26.230 Hello from a function. 02:26.830 --> 02:36.990 So again if I use Ctrl c Ctrl V and save it again if I execute this code again you see that this time 02:36.990 --> 02:38.710 it gives me twice. 02:39.390 --> 02:41.910 And as much as I ran. 02:41.910 --> 02:47.550 As much as I call the function, it will print me this text, this function. 02:48.110 --> 02:50.390 So also we have parameters. 02:50.390 --> 02:54.310 Information can be passed to function as parameters. 02:54.750 --> 03:00.870 So parameters are specified after the function name. 03:01.630 --> 03:02.070 Okay. 03:02.550 --> 03:04.550 Here inside. 03:05.070 --> 03:05.550 Okay. 03:05.590 --> 03:06.990 Inside the parenthesis. 03:07.110 --> 03:08.300 This parenthesis Parentheses. 03:08.700 --> 03:14.740 You could, uh, you can add as many parentheses parameters as you want. 03:14.780 --> 03:15.180 Okay. 03:15.500 --> 03:21.980 You can add a lot of parameters here, but just be careful to separate them with a camera. 03:22.620 --> 03:23.860 How can we do that? 03:23.940 --> 03:31.580 Let's, uh, in this function, let's say we have, uh, something like if name. 03:31.620 --> 03:32.980 Okay, anything. 03:33.580 --> 03:38.140 And right here I pass a parameter by this name. 03:38.140 --> 03:41.620 And I'm going to use that here if name okay. 03:42.780 --> 03:47.060 And function name. 03:47.060 --> 03:51.700 And here I am going to pass this if name here. 03:51.780 --> 03:58.340 Because while I created this function I told it that it needs to get an argument. 03:58.340 --> 04:02.580 And whenever I am calling the function I need to pass something to this. 04:02.580 --> 04:06.060 Okay, so here I am going to. 04:08.340 --> 04:11.780 Say my function Okay. 04:13.580 --> 04:14.900 It is something that you pass. 04:14.900 --> 04:16.740 You could write anything here. 04:17.100 --> 04:22.780 Now, if I execute the program again, you say that hello from from my function. 04:22.780 --> 04:23.900 From my function. 04:24.900 --> 04:25.260 Okay. 04:27.380 --> 04:31.540 So it is how you can pass a parameter to a function. 04:32.020 --> 04:42.940 And also we can um, we can use a default parameter, which is very, uh, very good sometimes. 04:43.260 --> 04:46.060 For example, right here. 04:48.260 --> 04:56.540 Um, I'm going to pass a default parameter to this if name is equal to my function. 04:56.540 --> 05:01.900 And okay, by default it is my function. 05:02.300 --> 05:06.060 And right now it is not necessary to give this okay. 05:06.100 --> 05:07.220 It's optional now. 05:10.700 --> 05:11.180 Okay. 05:11.220 --> 05:13.690 See hello from my function. 05:13.690 --> 05:15.090 It comes from here. 05:15.410 --> 05:25.890 But if I use Ctrl C and Ctrl V and this time I give something else, for example, name it and execute 05:25.890 --> 05:26.370 this. 05:26.650 --> 05:32.570 So this time it will give me hello from name instead of my function. 05:32.570 --> 05:34.050 It will give me this one. 05:34.210 --> 05:41.090 Now if I comment this you can comment in Visual Studio Code using Ctrl and hitting the slash. 05:41.650 --> 05:44.730 So it will give you a comment. 05:45.490 --> 05:46.770 So here see here. 05:46.770 --> 05:48.050 Hello from name. 05:48.530 --> 06:00.530 It is how you can use a default parameter using function and also function can return something. 06:00.690 --> 06:03.570 Okay, the later function will return a value. 06:03.610 --> 06:06.970 Use the return keyword or use the return statement. 06:07.290 --> 06:08.890 So now let's. 06:11.490 --> 06:19.090 Use another function and I'm going to name it this time. 06:19.570 --> 06:22.210 Mull means multiplication. 06:22.810 --> 06:25.930 In here I'm going to give an argument that is going to be x. 06:26.330 --> 06:27.770 Here I'm going to return. 06:28.290 --> 06:33.610 For example, two is going to be multiplied by x. 06:34.530 --> 06:35.690 And that is it. 06:35.770 --> 06:40.170 Now whenever I call this function and give a number to this. 06:40.610 --> 06:47.570 So it needs to multiply that number by two and then return the result for me. 06:47.570 --> 06:49.690 Let's print that function mul. 06:49.970 --> 06:54.050 And here give the number two and save it. 06:54.050 --> 06:55.330 Then call it. 06:55.370 --> 06:56.530 It gives me four. 06:56.690 --> 06:56.970 Why? 06:57.010 --> 07:02.930 Because four comes here and then two comes here that we give it right here. 07:03.050 --> 07:03.210 Okay. 07:03.210 --> 07:03.890 Two multiply. 07:03.930 --> 07:05.330 Two is equal to four. 07:05.810 --> 07:07.570 Now if I give four. 07:10.570 --> 07:12.370 Now you know that it is eight. 07:12.410 --> 07:13.050 Okay. 07:13.050 --> 07:17.450 That is how you can use return keyword with function.