WEBVTT 00:00.350 --> 00:07.270 C plus plus 11 introduce another way to use the for loop, which is intended to be used with the containers. 00:07.280 --> 00:11.930 So the C plus plus standard library contains templates for the container classes. 00:11.960 --> 00:18.430 These classes contain a collection of objects and provide access to those items in a standard way. 00:18.440 --> 00:23.790 The standard way is to iterate through a collection using an iterator object. 00:23.810 --> 00:30.260 More details about how to do it is will begin in the next lecture here, but this syntax requires an 00:30.260 --> 00:34.710 understanding of pointers and iterators so we will not cover them here. 00:34.730 --> 00:42.050 So the range based for loop gives a simple mechanism to access items in a container without explicitly 00:42.050 --> 00:43.490 using iterators. 00:43.490 --> 00:47.390 So the syntax is simple here for here, for loop. 00:47.390 --> 00:50.300 Here for declaration. 00:51.770 --> 00:52.940 An expression. 00:53.590 --> 00:56.860 And after that, the loop statement begins. 00:57.070 --> 00:58.960 Loop statement here. 00:58.990 --> 01:05.590 So the first thing is to pointed out that there are only two expressions and they are separated by the 01:05.590 --> 01:06.100 colon. 01:07.030 --> 01:12.790 So the first expression is used to declare the loop variable, which is of the type of the items in 01:12.790 --> 01:14.890 the collection being iterated throughout. 01:14.890 --> 01:21.280 And the second expression is gives an access to the collection in the C plus plus times. 01:21.280 --> 01:28.810 The collection that can be used are those that define a begin and end function that gives a access to 01:28.810 --> 01:34.780 iterators and also stack based arrays and the set based arrays that the compiler knows the size of. 01:34.780 --> 01:42.670 Here, the standard library defines a container object vector here in this here, let's create a vector 01:42.670 --> 01:51.010 and the vector template is a class that contains items of the type specified in the angled braces like 01:51.010 --> 01:53.110 that here vector. 01:55.390 --> 01:58.280 And we're going to create a string vector here. 01:58.300 --> 01:58.960 String vector. 01:58.960 --> 02:05.510 As you can see, we got an error because we have to include the vector library here. 02:05.530 --> 02:07.820 Import vector library, as you can see here. 02:07.840 --> 02:10.930 So we imported vector library and. 02:14.220 --> 02:19.890 So, you know, the vector is initialized in a special way that is new to a C plus plus 11. 02:19.890 --> 02:22.620 And this is called the list initialization. 02:22.620 --> 02:29.730 So this syntax allows you to specify the initial values of the vector in a list between curly braces 02:29.730 --> 02:30.180 here. 02:30.180 --> 02:38.520 So let's make an my cars variable and make it, for example, BMW, M. 02:39.990 --> 02:41.280 Fourth here. 02:43.360 --> 02:46.450 Portiere Fiat here. 02:47.200 --> 02:49.630 Volkswagen we're going to add here. 02:51.430 --> 02:52.570 Volkswagen. 02:52.750 --> 02:57.070 And we're going to add another Audi here. 02:57.490 --> 02:58.210 Here. 02:58.920 --> 03:03.690 And we're going to create a for loop for integer E. 03:04.820 --> 03:05.600 Zero. 03:05.630 --> 03:15.680 While Integer is less than my cast size and increase e by one and see out. 03:16.860 --> 03:17.250 Uh. 03:17.280 --> 03:18.000 Okay. 03:18.740 --> 03:20.770 See out my cars. 03:20.780 --> 03:23.200 Dot add e. 03:24.690 --> 03:26.250 And end line. 03:28.950 --> 03:30.030 And line here. 03:33.790 --> 03:34.510 So. 03:36.390 --> 03:37.230 Here. 03:39.000 --> 03:49.200 The vector class has a member of called member function called size that the called through the dot 03:49.200 --> 03:55.860 operator here which means the call this function on this object that returns the number of items in 03:55.860 --> 03:56.550 the vector. 03:56.550 --> 04:00.060 So each item is accessed. 04:01.160 --> 04:03.440 Using add function here. 04:04.240 --> 04:06.880 Passing the object index. 04:07.600 --> 04:11.550 The one big problem with this code is that it uses random access. 04:11.560 --> 04:15.790 That is, it accesses each item using its index. 04:15.790 --> 04:22.990 So this is a property of vector, but standard library container types do not have random access. 04:23.350 --> 04:27.100 Now we're going to create another range based loop here. 04:29.840 --> 04:31.020 Arranged baseball. 04:31.050 --> 04:32.520 This is going to be a range based loop. 04:34.420 --> 04:35.470 Based. 04:36.950 --> 04:41.420 Slope here and let's create the previous example we did here. 04:41.420 --> 04:48.770 So for string model, my car model. 04:50.390 --> 04:53.330 Oh, yes, my car model here. 04:54.970 --> 04:56.320 And my car's. 04:59.430 --> 05:00.870 And see out. 05:03.180 --> 05:07.320 My car model and inline. 05:07.500 --> 05:08.310 So. 05:09.590 --> 05:11.390 Let's print it again. 05:13.160 --> 05:13.940 And. 05:14.800 --> 05:16.120 Here say out. 05:17.810 --> 05:19.100 Uh, just to make. 05:19.100 --> 05:20.180 Make it look nice. 05:23.350 --> 05:24.460 Look here. 05:33.690 --> 05:34.350 Here. 05:34.710 --> 05:38.190 So this is the first example and this is the second. 05:38.280 --> 05:41.580 So actually the output is the same. 05:41.910 --> 05:47.350 They look, they look same, but each item is accessed using the add function here. 05:47.370 --> 05:53.460 But in this leg here, the we just use the range based loop here. 05:56.400 --> 06:01.110 So the standard library containers type, as I said earlier, do not have random access. 06:01.110 --> 06:05.430 And this for loop uses the range based for here. 06:05.700 --> 06:09.130 So actually we can create another work. 06:09.300 --> 06:16.020 So as you know, this type here works with any of the standard container types and for arrays allocated 06:16.020 --> 06:16.950 on the stack here. 06:16.950 --> 06:18.900 So we're going to create another here. 06:19.290 --> 06:27.120 Um, let's make it my car years here, my cars here. 06:28.410 --> 06:28.890 Here. 06:29.250 --> 06:31.980 And, for example. 06:33.210 --> 06:33.560 Um. 06:34.770 --> 06:36.030 2002. 06:36.060 --> 06:37.500 2005. 06:38.340 --> 06:39.960 1989. 06:41.230 --> 06:42.000 Okay. 06:42.240 --> 06:43.380 And how many? 06:43.440 --> 06:44.670 Yeah, we have five. 06:44.700 --> 06:46.350 Let's create a five to make it. 06:46.890 --> 06:51.090 Which are we going to print it here or make it for where you want to? 06:51.420 --> 06:53.130 Uh, you want access here. 06:53.910 --> 06:55.740 And 2010. 06:57.140 --> 07:01.190 So and let's print it out using this range based for. 07:01.520 --> 07:04.550 For loop here, for integer. 07:05.030 --> 07:06.830 Uh, here, here. 07:07.010 --> 07:10.820 And my cars here and here. 07:10.850 --> 07:15.560 C out my here and. 07:16.100 --> 07:16.900 And line. 07:19.750 --> 07:20.170 Here. 07:20.200 --> 07:22.120 As you can see, we printed this as well. 07:22.120 --> 07:28.450 In this case, the compiler knows the size of the array because the compiler has allocated the array 07:28.450 --> 07:29.050 here. 07:29.050 --> 07:31.360 And so it can determine the range. 07:31.390 --> 07:36.880 The range based for loop will iterate through all the items in container. 07:36.880 --> 07:43.720 But as with the previous version, you can leave the for loop using the break, return, throw or go 07:43.720 --> 07:44.200 to here. 07:44.200 --> 07:51.820 So and you can indicate that the next loop should be executed using the condition continue statement 07:51.820 --> 07:53.950 here so we can make it like that here. 07:54.820 --> 07:55.480 Okay. 07:55.480 --> 07:56.380 If. 07:57.990 --> 07:58.410 Make it. 07:58.560 --> 07:59.970 Let's make an if statement. 07:59.970 --> 08:01.710 Write an if statement here. 08:01.950 --> 08:02.760 So. 08:03.850 --> 08:12.400 If our year equals to two 1989, make it just an. 08:13.480 --> 08:14.050 Okay? 08:14.320 --> 08:16.000 No, actually. 08:16.870 --> 08:17.100 It. 08:17.230 --> 08:21.070 Uh, the year car is too old. 08:21.100 --> 08:21.970 See out. 08:23.090 --> 08:24.920 Car is to. 08:26.460 --> 08:26.940 All. 08:28.120 --> 08:29.590 Old classic. 08:31.000 --> 08:32.440 We'll make it classic car. 08:32.740 --> 08:36.700 And of course, we have to end line here to make it look nice. 08:36.700 --> 08:41.740 And else here, just print the year of the car here. 08:42.010 --> 08:43.210 Make it here. 08:43.210 --> 08:55.090 As you can see here, when it comes to the 1989, it shows the if statement is executed and else the 08:55.120 --> 08:58.300 C out here is just printed to the screen here.