WEBVTT 00:01.860 --> 00:03.330 After the return type. 00:04.300 --> 00:08.710 Uh, the parameters, the function name and have been determined. 00:08.740 --> 00:12.430 You need to define the body of the parameters. 00:12.430 --> 00:15.680 So we're going to firstly make the return time. 00:15.700 --> 00:23.080 Then our function name, for example, my function, the parameters of this function is going to get, 00:23.080 --> 00:25.030 for example, my integer. 00:25.030 --> 00:28.660 And this is the function. 00:29.960 --> 00:31.070 Uh, body here. 00:31.070 --> 00:39.470 So the code for a function must appear between a pair of braces here, as you can see here. 00:39.470 --> 00:46.490 So if the function returns a value, then the function must have at least one line. 00:46.520 --> 00:51.800 The last line in the function with the return statement here. 00:52.790 --> 01:00.320 So this must return the appropriate type or type that can be implicitly converted to the return type 01:00.320 --> 01:01.430 of the function. 01:01.430 --> 01:09.500 So as mentioned before, if the function is declared as auto here, the compiler will deduce the return 01:09.500 --> 01:09.800 type. 01:09.800 --> 01:14.840 So in this case, the return statement must return the same type. 01:15.450 --> 01:21.630 Now, when a function is called, the compiler checks all the overloads of the function to find one 01:21.630 --> 01:24.150 that matches the parameter in the calling code. 01:24.150 --> 01:30.330 So if there is a no exact match, then the standard and user defined type conversions are performed. 01:30.330 --> 01:37.130 So the values provided by the calling code may be different type from parentheses here. 01:37.140 --> 01:38.760 So parameters. 01:39.210 --> 01:45.660 So by default parameters are passed by value and the copy is made. 01:45.660 --> 01:47.010 So which means that the. 01:47.920 --> 01:53.230 Parameters are treated as local variables in the function like that here. 01:53.230 --> 01:58.390 So you can't use the my integer variable outside the function here. 01:58.540 --> 02:04.240 These are the just local variables that you can use these variables inside the function. 02:04.240 --> 02:05.020 So. 02:07.200 --> 02:13.320 Uh, the variety of the function can decide to pass parameter by reference either through the pointer 02:13.320 --> 02:14.790 or a C plus plus reference. 02:14.790 --> 02:22.200 So pass by reference means that the variable in the calling code can be altered by the function, but 02:22.200 --> 02:27.150 this can controlled by making the parameters constant here. 02:27.150 --> 02:34.470 So in which case the reason for passing by reference is to prevent the potentially costly copying being 02:34.470 --> 02:35.040 made. 02:35.040 --> 02:41.880 So the built in arrays are always passed as a pointer to the first item to the array. 02:41.880 --> 02:47.250 Here, the compiler will create the temporaries when needed. 02:47.250 --> 02:51.750 So for example, when a parameter here, for example, let's create a void. 02:51.750 --> 02:59.760 If the when a parameter is a const reference and the calling code uh, passed pass as a literal, a 02:59.760 --> 03:04.890 temporary object is created here and it's only available to the function here. 03:05.100 --> 03:13.680 Let's create a function float and here we're going to make the F here. 03:15.850 --> 03:19.420 F 1.0, for example. 03:19.450 --> 03:20.740 Or double. 03:21.670 --> 03:22.510 Double d. 03:23.590 --> 03:25.780 D equals. 03:26.640 --> 03:27.620 2.0. 03:27.630 --> 03:29.880 As you know, this is the plot number. 03:29.880 --> 03:33.840 And here and we're going to. 03:34.750 --> 03:45.400 Add the F pass the D variable, the double variable to the our f function here which returns nothing. 03:45.400 --> 03:48.580 But we have a const parameter here. 03:49.330 --> 03:49.540 The. 03:51.240 --> 03:52.770 So here, this is. 03:52.770 --> 03:53.730 Okay. 03:53.820 --> 03:54.450 Okay. 03:54.450 --> 03:57.960 And temporary float is created. 03:58.260 --> 04:01.170 And this is actually the almost the same. 04:01.710 --> 04:03.600 And it's okay. 04:03.600 --> 04:10.950 And the temporary float is created here actually, in this. 04:10.950 --> 04:12.000 Not in this line. 04:12.000 --> 04:13.590 In this line we have, uh. 04:13.590 --> 04:14.280 Okay. 04:14.280 --> 04:22.440 And it code can compile successfully and in f when we pass 1.0 as parameter, the temporary float is 04:22.440 --> 04:22.830 created. 04:22.830 --> 04:31.950 And, um, when we're going to pass the D as a parameter, the temporary float is created as well here 04:31.950 --> 04:36.870 and we can pass the initializer list list in this functions here. 04:36.870 --> 04:39.960 So you can pass initializer list as a parameter. 04:39.960 --> 04:44.160 If that list can be converted to the type of the parameter. 04:44.160 --> 04:48.120 So for example, let's we're going to create another struct here. 04:48.150 --> 04:53.010 Actually, we can delete this codes, we can create another struct here. 04:53.010 --> 04:54.510 We can delete this as well. 04:55.930 --> 04:58.750 Uh, struct point here. 04:58.780 --> 05:02.080 This is going to take an integer x here. 05:02.200 --> 05:05.140 An integer A or integer. 05:06.280 --> 05:07.930 Integer B here. 05:09.470 --> 05:10.100 Here. 05:10.100 --> 05:15.980 So we're going to make the ender function named set point. 05:16.430 --> 05:19.550 And the point, as you can see, the point is a struct. 05:19.550 --> 05:23.480 We're going to take the point struct as a parameter. 05:24.510 --> 05:26.820 And name it here. 05:26.820 --> 05:31.280 So in the main function, we're going to code a point. 05:31.290 --> 05:42.330 We're going to create a point object named P and reach the P dot A equals one and P dot B equals one 05:42.330 --> 05:42.990 as well. 05:42.990 --> 05:45.720 And here we're going to set point. 05:45.750 --> 05:53.160 We're going to use the set point function and we're going to pass to pass P as a parameter. 05:53.640 --> 05:56.550 And we're going to set point here. 05:57.660 --> 06:00.220 Uh, using the curly braces here. 06:00.240 --> 06:02.970 One and one here. 06:03.960 --> 06:09.920 And we're going to return zero, as always in main function here. 06:09.930 --> 06:11.010 So. 06:12.600 --> 06:17.760 Uh, this code defines a structure that has two members. 06:17.910 --> 06:18.660 Here. 06:18.690 --> 06:20.520 Actually, let's make it look nice here. 06:20.520 --> 06:21.010 Like this. 06:21.030 --> 06:27.120 This structure has a two members, and in the main function, a new instance of point is created on 06:27.120 --> 06:32.400 the stack, and it is initialized by accessing their members directly. 06:32.400 --> 06:39.570 So the instance is then passed to a function that has point parameters as the parameter of set point 06:39.600 --> 06:40.080 here. 06:40.110 --> 06:42.390 Set point is passed by value. 06:42.420 --> 06:49.920 The compiler creates a copy of the structure on the stack of the function here, and the second call 06:49.920 --> 06:51.660 of the set point does the same. 06:51.660 --> 06:58.440 The compiler will create a temporary point object on the stack of the function and initialize it with 06:58.440 --> 07:01.320 the values in the initializer list.