WEBVTT 00:01.150 --> 00:09.070 C plus plus 11 introduced a mechanism for declaring that a variable's type should be determined from 00:09.070 --> 00:14.980 the data it is initialized with, and that is the auto keyword here. 00:15.310 --> 00:23.650 So this is a minor confusion here because the prior C plus plus 11 prior to C plus plus 11, the auto 00:23.650 --> 00:27.010 key was used to declare the automatic variables. 00:27.040 --> 00:32.110 That is the variables that are automatically allocated on the stack in a function. 00:32.110 --> 00:40.240 So other than variables declared at a file scope or a static, are the other variables in this course 00:40.240 --> 00:46.870 so far have been automatic variables, and automatic variables are the most widely used storage class. 00:47.470 --> 00:56.590 So since it was optional and applicable to most variables, the auto keyword was rarely used in C plus 00:56.590 --> 00:57.210 plus. 00:57.220 --> 01:00.710 So the C plus plus 11 took advantage of this. 01:00.710 --> 01:07.820 Remove the old meaning and gave the author the whole new meaning here. 01:07.820 --> 01:15.890 So if you're compiling all C plus plus code with the C plus plus 11 compiler and that old code uses 01:15.920 --> 01:24.140 auto, so you will get errors because the new compiler will assume auto will be used with the variables 01:24.140 --> 01:27.230 with no specified type. 01:27.230 --> 01:28.280 So. 01:29.200 --> 01:34.170 If this happens, simply search and delete each instance of auto. 01:34.180 --> 01:38.530 So it was redundant in C plus plus prior to C plus plus 11. 01:38.530 --> 01:43.210 And there was a little reason for developers to use it here. 01:43.240 --> 01:50.710 The auto keyword means that the compiler should create a variable with the type of the data that is 01:50.710 --> 01:51.670 assigned to it. 01:51.670 --> 01:55.230 So the variable can only have a single type. 01:55.240 --> 02:00.190 The type the compiler decides is a type it needs for the data assigned to it. 02:00.370 --> 02:06.670 So and you cannot use the variables elsewhere to hold data of a different type because the compiler 02:06.670 --> 02:10.270 needs to determine the type from an initializer. 02:10.270 --> 02:16.300 And it means that all auto variables must be initialized. 02:17.200 --> 02:17.920 Now. 02:18.190 --> 02:21.150 Now, I want to do some examples here. 02:21.160 --> 02:27.880 So let's create an auto variables, which I will explain all of these auto variables later and add comments 02:27.880 --> 02:28.720 to it. 02:29.380 --> 02:34.480 For example, 42 auto be 42. 02:36.260 --> 02:36.830 Here. 02:36.860 --> 02:44.060 Auto c 42 lx here auto d here. 02:44.840 --> 02:50.150 Um 1.11.0 f auto. 02:51.120 --> 02:51.960 E here. 02:53.490 --> 02:55.590 1.0. 02:57.000 --> 02:57.900 Auto. 02:59.690 --> 03:00.740 If here. 03:02.510 --> 03:04.850 Uh, if it's going to be character. 03:10.760 --> 03:11.180 Here. 03:14.960 --> 03:15.950 And auto. 03:18.590 --> 03:19.130 Here. 03:19.160 --> 03:19.640 True. 03:22.160 --> 03:22.940 Here. 03:23.510 --> 03:28.630 Now I want to add, um, variables after it. 03:28.640 --> 03:40.280 So this is the integer we created integer type because we assigned to just an integer and here we created 03:40.280 --> 03:43.790 the long type, just the long integer. 03:44.390 --> 03:47.780 So we created long, long integer. 03:48.880 --> 03:49.420 Here. 03:49.420 --> 03:51.510 We created the float. 03:52.370 --> 03:53.630 Here. 03:54.620 --> 04:03.890 Double note that there is no syntax to specify that an integer value is a single byte or two byte, 04:03.890 --> 04:11.240 so you cannot create an unsigned character variables or short variables this way. 04:11.880 --> 04:15.010 Uh, and here we created the character. 04:15.020 --> 04:17.300 Just a usual normal standard character. 04:18.410 --> 04:21.410 And here we created the bull here. 04:22.560 --> 04:27.630 So this is a tribal use of the auto keyword. 04:27.630 --> 04:36.690 You should some sometimes you create this auto keyword with this and the compiler will assign the type 04:36.690 --> 04:39.330 of this variable automatically. 04:39.330 --> 04:44.250 So now I want to create another example to show you how this happens. 04:44.250 --> 04:48.870 And here this things might might get confusing. 04:48.870 --> 04:56.940 So don't worry if you don't know about the tuple or vectors here, which you will learn in later lectures. 04:56.940 --> 05:04.770 So now I want to create a vector that will take two, uh, one tuple, uh, in the tuple we're going 05:04.770 --> 05:06.840 to have string and integer. 05:08.110 --> 05:10.180 Here, we're going to create the vector. 05:10.360 --> 05:13.180 As you can see here, vector is not a built in type. 05:13.180 --> 05:18.910 So we have to import from the import class of vector to use it. 05:18.910 --> 05:23.380 And as you can see here, the compiler created a include vector here. 05:24.460 --> 05:26.830 The vector here tuple. 05:28.350 --> 05:30.720 String integer here. 05:30.750 --> 05:37.800 So as you can see, we have a tuple and we need to import the string here. 05:39.820 --> 05:43.210 And here we're going to name it my cars. 05:44.180 --> 05:50.510 Uh, as you can see, we got an error because we didn't actually included the tuple here. 05:50.510 --> 05:54.620 So that's why we're going to include include. 05:55.320 --> 06:01.290 Couple here, as you can see here, our error gone away and then. 06:02.700 --> 06:03.300 Here. 06:03.660 --> 06:08.730 We're going to add variables to my car's vector. 06:08.760 --> 06:10.260 Here, my cars. 06:10.260 --> 06:11.800 I will explain all of these codes here. 06:11.820 --> 06:12.750 Don't worry. 06:13.350 --> 06:19.860 My car's pushback back make topple and we're going to pass the. 06:21.930 --> 06:26.960 For example, let's name some car BMW and its year here. 06:27.270 --> 06:32.280 As you can see, the first is string and the second parameter is integer. 06:32.280 --> 06:38.250 So let's input our the date of production. 06:38.580 --> 06:44.120 The year of production of our car, for example, 2001. 06:44.130 --> 06:45.420 My cars. 06:45.450 --> 06:47.820 Or let's make a model of it. 06:47.820 --> 06:49.500 So make it look nicer. 06:52.110 --> 06:55.080 5/5 series here. 06:55.110 --> 06:58.070 My cars push back. 06:58.770 --> 07:00.120 Make Topple. 07:00.810 --> 07:02.010 The fourth. 07:03.450 --> 07:04.290 Uh. 07:05.690 --> 07:06.380 Mustang. 07:06.770 --> 07:07.820 Mustang. 07:07.910 --> 07:08.750 Here. 07:10.040 --> 07:11.510 1989. 07:12.320 --> 07:13.580 My cars. 07:14.560 --> 07:16.330 The pushback. 07:17.680 --> 07:18.970 Make a couple. 07:20.960 --> 07:23.150 Uh, Volkswagen Golf here. 07:23.150 --> 07:25.370 2010. 07:26.680 --> 07:27.580 My car. 07:27.580 --> 07:28.150 Start. 07:28.150 --> 07:29.170 Push back. 07:29.870 --> 07:30.690 Make. 07:30.710 --> 07:31.340 Make. 07:31.380 --> 07:32.180 Topple. 07:33.400 --> 07:34.060 Uh, here. 07:34.060 --> 07:37.990 We're going to input the Land Rover. 07:38.500 --> 07:40.270 Land Rover. 07:41.380 --> 07:44.440 Land Rover here. 07:46.190 --> 07:49.610 2015 here. 07:50.030 --> 07:59.720 Now we're going to create a for loop here for here, Tupple string integer here. 07:59.990 --> 08:03.320 It's going to be like my vehicles. 08:06.000 --> 08:08.040 Here and then. 08:09.360 --> 08:10.470 My cars. 08:10.470 --> 08:11.700 We will iterate. 08:11.730 --> 08:17.550 My cars one by one here, and then we're going to print it out here. 08:17.580 --> 08:18.570 C out. 08:19.410 --> 08:20.130 C out. 08:20.130 --> 08:26.010 As you can see, we cannot use C out because we have to use a include STD. 08:27.930 --> 08:28.350 Here. 08:30.040 --> 08:32.250 Input output stream and see. 08:33.910 --> 08:35.950 Get here. 08:41.490 --> 08:42.150 Get. 08:42.940 --> 08:44.440 My vehicles. 08:45.870 --> 08:46.230 Here. 08:49.440 --> 08:50.100 Get. 08:50.930 --> 08:51.700 One. 08:51.710 --> 08:53.260 I will explain all of these codes. 08:53.270 --> 08:53.780 Don't worry. 08:53.780 --> 08:54.380 Here. 08:55.670 --> 08:58.040 And get one. 08:58.430 --> 09:00.530 My vehicles. 09:02.590 --> 09:04.060 And end line. 09:05.600 --> 09:07.700 And let's run our code here. 09:11.510 --> 09:12.020 Okay. 09:14.900 --> 09:17.840 Make it look nice and print it out again. 09:18.770 --> 09:25.100 So this code, as you can see, this is our okay, make it run it again. 09:25.100 --> 09:36.830 So here, as you can see here, this code uses the vector container here to as you know, we haven't 09:36.830 --> 09:39.920 used vector or tuples, so don't worry about them. 09:40.430 --> 09:46.280 You will learn in next lectures about vectors and tuples and other technologies in C plus plus here. 09:46.280 --> 09:51.020 But just keep in mind that you will learn it and don't panic here. 09:51.440 --> 09:58.490 So, uh, here the vector stores two value items using this tuple. 09:59.670 --> 10:01.800 So the tuple class is simple. 10:01.830 --> 10:08.460 You declare a list of the types of items in the tuple object and the declaration between the angled 10:08.700 --> 10:09.870 braces here. 10:09.870 --> 10:18.060 So the tuple string integer declaration says that the object will hold a string and an integer. 10:18.060 --> 10:24.780 So in that order, the make tuple function here make tuple function here. 10:25.720 --> 10:34.540 Is provided by the C plus plus standard library and will create a tuple object containing two values. 10:34.540 --> 10:40.150 The first is a string and the second is integer. 10:40.330 --> 10:45.760 So the pushback function will put the item into the vector container. 10:45.760 --> 10:53.080 So after the for cost of the pushback function, the here the vehicles. 10:54.340 --> 11:03.070 The vehicle's variable will contain actually the my car's variable will contain four items and each 11:03.100 --> 11:11.590 in the four items we're going to have two variables and each one is tuple with the name and birth year. 11:11.770 --> 11:20.710 And here, as you can see, the range for loops throughout the container and on each loop assigns the 11:21.040 --> 11:27.580 my vehicle variable with the next item in the container of my cars. 11:27.580 --> 11:34.600 So the values in the tuple are printed to the console, as you can see here in this function. 11:35.770 --> 11:37.170 And for loop here. 11:37.170 --> 11:43.830 So an item in the tuple here is accessed using the get. 11:45.320 --> 11:48.920 Parameterized function from the tuple. 11:48.950 --> 11:52.010 Here, as you can see here, this is a get function. 11:52.280 --> 11:55.160 This get function belongs to tuple here. 11:55.820 --> 11:56.960 So. 11:59.430 --> 12:08.130 And here, as you can see here, the first we assigned zero to get the first object of this tuple and 12:08.130 --> 12:17.370 then a space here and then get one, uh, gets the year of item in the tuple. 12:17.370 --> 12:22.800 And the result of this code is this output here. 12:23.010 --> 12:30.690 So the next text has poor formatting because it does not take into account the length of the names. 12:30.690 --> 12:35.730 So this can be addresses using the manipulators in next lectures. 12:35.730 --> 12:38.490 So we're going to create here. 12:39.930 --> 12:44.190 Uh, take a look at the for loop here. 12:46.040 --> 12:48.560 So the type of the. 12:49.350 --> 12:54.450 My vehicles is tuple, string and integer. 12:54.450 --> 13:02.340 So this is fairly simple type and as you use the standard template more, you could end up with some 13:02.340 --> 13:06.600 complicated type, particularly when you use iterators. 13:06.600 --> 13:10.690 So this is where our tool becomes useful. 13:10.820 --> 13:13.560 The here we're going to create a code. 13:15.020 --> 13:17.580 Okay, so let's comment it out. 13:19.160 --> 13:19.640 Here. 13:22.740 --> 13:23.010 Oops. 13:25.110 --> 13:25.380 Here. 13:28.640 --> 13:29.510 Commented out. 13:31.020 --> 13:32.250 And here. 13:36.700 --> 13:37.420 For. 13:38.800 --> 13:41.140 Autonomy vehicles. 13:43.490 --> 13:48.920 Girls and my cars and see out. 13:51.260 --> 13:53.420 Get zero. 13:54.970 --> 13:58.120 From the my vehicles. 13:59.360 --> 14:01.670 Vehicles and. 14:04.010 --> 14:04.460 Here. 14:06.000 --> 14:12.480 Get one from the my vehicles here and end line. 14:14.490 --> 14:17.760 So here. 14:20.580 --> 14:23.340 This is where R2 becomes useful here. 14:23.340 --> 14:28.090 So this code is the same but easier to read. 14:28.110 --> 14:32.670 So the my vehicles variable is still typed. 14:33.270 --> 14:44.340 It has a tuple string integer, but auto means you do not have to explicitly code this in like this 14:44.340 --> 14:45.330 example here. 14:45.330 --> 14:50.220 So this is more readable code and more useful on this case here.