WEBVTT 00:00.910 --> 00:06.710 Us far we've only been using C strings and we've had to be very mindful about how they work. 00:06.720 --> 00:13.200 We always had to account for the null character and we had to use the C string library to copy strings. 00:13.290 --> 00:18.420 I mean I use them for the majority of this course because it's important for you to understand how things 00:18.420 --> 00:23.520 really work under the hood whenever you're programming there should never be anything that you would 00:23.520 --> 00:25.980 consider as magical. 00:26.130 --> 00:31.140 Otherwise you won't understand their implications on the code as a whole. 00:31.170 --> 00:36.070 Understanding your program as a whole is really the key to making it the best it can be. 00:38.470 --> 00:48.010 But instead of using C strings we could have been using C++ strings and to do that we use the string 00:48.010 --> 01:01.520 library case so not C string but string OK and this actually gives us access to a real string type so 01:01.790 --> 01:06.800 we type string like this and give it a name. 01:08.380 --> 01:14.440 We can actually have regular strings as if it was a real type. 01:14.440 --> 01:14.910 OK. 01:15.030 --> 01:21.840 And it is in this case and there's lots of things that we can do with it. 01:21.840 --> 01:23.640 For example we can put it 01:26.810 --> 01:40.220 ministering seek out just like normal K and we can even get it from input so we could actually say please 01:40.710 --> 01:42.020 dear string 01:45.110 --> 01:50.160 this he get. 01:50.660 --> 01:55.210 It's actually making a new string for this string to 01:58.440 --> 02:01.220 actually put it into my string too. 02:01.230 --> 02:07.610 So instead of using what you have been using which is the you tell our our own huge sales library actually 02:08.230 --> 02:12.340 and we wrote a function in there to actually get a string right. 02:12.570 --> 02:18.750 We can just use C in instead and have that kind of nice support. 02:19.410 --> 02:32.780 And even in output it's the same string to this case if you're in this C great solo just like we thought 02:33.320 --> 02:35.890 and we can even get it right. 02:36.290 --> 02:41.850 Everyone even print out every day. 02:45.770 --> 02:53.780 So there's other things we can do which is something really nice which is a pending strings together. 02:54.200 --> 03:01.590 So you could say make another string say string three 03:04.710 --> 03:06.430 and we can actually append them together. 03:06.440 --> 03:15.860 So say my string plus my string to k. 03:15.950 --> 03:24.410 So we're basically adding my string to or reading my string to do my string. 03:24.620 --> 03:32.020 Ok so if we put that say results 03:34.230 --> 03:37.780 is I string three 03:41.000 --> 03:44.380 of your wryness. 03:44.740 --> 03:50.700 Everyone result is Hello everyone so it actually adds them together. 03:50.740 --> 04:02.040 Pens them together they just kind of cool and we could even have done this like this say my string three 04:03.160 --> 04:10.440 sequels Samoa thing that's so sexy. 04:10.460 --> 04:11.470 But for 04:14.230 --> 04:17.640 free again everyone 04:20.820 --> 04:28.630 so everyone actually append this thing this exclamation mark to the string as well. 04:29.990 --> 04:30.650 OK. 04:31.060 --> 04:37.390 And the edition will actually again appends strings together and notice that we don't have to worry 04:37.390 --> 04:44.200 about the memory of the string anymore and we always have to worry about how big the array for this 04:44.320 --> 04:45.180 string was. 04:45.190 --> 04:54.190 But now we don't really have to worry about that because internally the string type we ever hear will 04:54.250 --> 04:56.680 probably do everything for us. 04:56.680 --> 05:03.440 In fact it will do everything for us though it internally it might do some dynamic memory allocations 05:03.460 --> 05:07.920 but we don't really have to worry that the string itself will take care of it. 05:09.400 --> 05:21.940 One other nice thing is that just like our C strings we can actually set characters directly. 05:22.000 --> 05:29.090 So when you actually use the indexing operator they like this. 05:29.090 --> 05:30.760 Just like a C string. 05:30.940 --> 05:35.620 So it's just like with C strings. 05:37.250 --> 05:41.750 So we can actually access individual elements individual characters. 05:41.750 --> 05:51.740 In this case of the string itself the other nice thing about String type is that we can actually get 05:51.770 --> 05:54.430 the length of the string. 05:55.080 --> 06:02.600 Unlike with C string before which we have to use a function to do that this type actually provides the 06:02.600 --> 06:04.580 length already. 06:04.580 --> 06:08.240 So if I said zero length 06:12.130 --> 06:29.950 string is or of say just say my string theory is and we said My string three dot like 06:34.400 --> 06:38.100 if you write and that's everyone 06:40.350 --> 06:43.110 and the length of my string is 14 or so. 06:43.140 --> 06:54.360 One two three four five six seven eight nine 10 11 12 13 14 insets 14 characters so that's the night. 06:54.420 --> 06:55.330 That's nice. 06:55.330 --> 07:01.220 And so we don't have to use Sterling anymore for string lengths. 07:04.130 --> 07:16.430 And one very interesting part of the string type is we can actually create a C string from it. 07:16.880 --> 07:20.800 So I said See 07:23.510 --> 07:31.500 C string tension is say my string. 07:31.520 --> 07:35.080 3. C string. 07:35.240 --> 07:37.690 Stir. 07:37.860 --> 07:44.280 So this actually gives you a conc char star. 07:44.390 --> 07:44.690 OK. 07:44.700 --> 07:48.390 So it's a constant character pointer. 07:49.330 --> 07:54.690 Or a pointer to a character constant if you will. 07:55.140 --> 07:57.610 Which is really nice. 07:58.050 --> 08:04.840 And you may be wondering why would I care about this if I have this string type now. 08:05.280 --> 08:12.420 Well we care about it because Still if you want to interface with C or C libraries which we will be 08:12.420 --> 08:14.730 doing in the next section 08:17.610 --> 08:21.210 C only has C strings right. 08:21.270 --> 08:26.670 That's why that's why they're called Caesarians factors because they're from the C language. 08:26.670 --> 08:34.640 And in order to interface with some of the functions that we're going to need we actually have to use 08:34.640 --> 08:38.930 this dot C string function. 08:39.530 --> 08:43.620 But we'll see that in the next section. 08:43.650 --> 08:58.270 One thing to remember in a very important thing is if we're using strings with functions so if we had 08:58.270 --> 09:00.550 some function like this 09:03.240 --> 09:05.280 if you do if you did this 09:10.400 --> 09:13.420 hey this is passing it by value. 09:17.170 --> 09:25.660 And the reason why I went through all the trouble of showing you see strings before is we know that 09:27.370 --> 09:33.210 in this case it would actually do copy OK. 09:33.370 --> 09:45.970 So it actually copy all the values in the string K which is all the characters in what basically amounts 09:45.970 --> 09:50.860 to is the big array into this function k. 09:50.890 --> 09:55.500 So it will actually do a real copy which could be very slow. 09:55.840 --> 10:03.740 So instead of doing this with strings you should always be doing the pass by reference. 10:04.210 --> 10:09.240 Or if you don't need to change it pass it by constant reference. 10:09.250 --> 10:15.030 Otherwise you'll actually incur potentially a very big penalty. 10:15.030 --> 10:16.860 It will be very slow. 10:16.860 --> 10:18.580 It will waste a lot of memory. 10:18.810 --> 10:19.620 OK. 10:19.620 --> 10:26.370 So just remember that when you're passing strings to functions it should be either by reference or by 10:26.910 --> 10:28.470 constant reference. 10:28.470 --> 10:37.880 Or if you really need to change something like string pointer OK so other than that they really just 10:37.880 --> 10:41.260 work like any other type. 10:41.600 --> 10:49.820 So we'll be using them from now on our next game. 10:49.820 --> 10:56.420 And and actually in the last lecture of this section which will be working on the mini project that 10:56.420 --> 11:04.280 we started in the last section a bit more so in the next lecture I want to go over vector's.