WEBVTT 00:01.230 --> 00:05.670 Hello again! In this video, we are going to look at removing elements from strings. 00:07.020 --> 00:09.570 The erase function does what you might expect. 00:09.990 --> 00:14.460 It will remove a character or characters from a string object. 00:15.570 --> 00:21.060 We call it on the string that we want to erase from. The first argument is the position where we want 00:21.060 --> 00:22.200 to start erasing. 00:22.710 --> 00:25.320 And the second document is the number of characters. 00:26.370 --> 00:30.210 So here we have three, which is the second letter 'l'. 00:30.600 --> 00:33.510 And one means we just wants to erase one character. 00:34.110 --> 00:35.580 So this will actually start erasing 00:35.580 --> 00:41.340 at that character, not before it or after it, actually at that character, and it will just 00:41.340 --> 00:42.330 erase one character. 00:42.990 --> 00:44.210 So that will be that letter 'o'. 00:45.660 --> 00:48.390 And again, we can use the return value from find. 00:49.380 --> 00:55.700 So we are going to find the first occurrence of the letter 'e' and then erase two characters, so that will erase 00:55.770 --> 00:56.630 'e' and 'l'. 00:59.190 --> 01:06.120 So here is that code. We erase the second letter 'l', then we erase 'e' and 'l'. So we should be just left 01:06.120 --> 01:07.260 with "ho". 01:09.170 --> 01:09.740 And there we are. 01:10.910 --> 01:16.880 So it is not quite Christmas yet, but maybe it is topical to have ho. Ho, ho ho? Maybe not! 01:20.840 --> 01:23.300 We can also use erase with iterators. 01:24.200 --> 01:29.270 If we just use a single iterator, it will erase the corresponding element. 01:29.690 --> 01:35.840 So if we have an iterator to the first element, by calling begin(), that will erase the first element. 01:36.650 --> 01:42.560 If we have a range of iterators, that will erase all the elements in the range up to, but not including, 01:42.560 --> 01:43.940 the end of the range. 01:44.600 --> 01:47.450 So that is the half open range that we mentioned before. 01:48.470 --> 01:54.350 If we have, for example, an iterator to the second element and the last element, this will erase 01:54.350 --> 02:00.350 all the elements from the second element up to, but not including, the last element. 02:03.150 --> 02:04.650 And we can try that out. 02:05.100 --> 02:11.700 So you remember that end() minus one is the actual last element. And end() on its own is the last element 02:11.700 --> 02:12.210 plus one. 02:14.330 --> 02:15.200 So what do we get? 02:16.250 --> 02:19.840 So we erase the first element and we get "allo". 02:21.820 --> 02:26.890 And then we erase everything except the first and last element of that string. 02:27.130 --> 02:28.480 So we end up with "eo". 02:33.720 --> 02:38.430 If we want to remove some characters from a string and replace them with other characters, then we can 02:38.430 --> 02:39.330 use replace(). 02:42.450 --> 02:47.640 The first argument to replace is the position where we want to start replacing. 02:48.970 --> 02:52.300 The second argument is the number of characters we want to replace. 02:52.930 --> 02:58.390 So we are starting from the letter 'H' and replacing five characters, and then we are going to replace 02:58.390 --> 03:01.180 them with the third argument, which is "Goodbye". 03:06.640 --> 03:10.900 And of course, being careful programmers, we check that we have actually got a valid index before we use 03:10.900 --> 03:11.140 it. 03:11.410 --> 03:12.880 So we put in this check here. 03:15.150 --> 03:18.180 And then we should end up with a string that says, "Say Goodbye". 03:19.930 --> 03:22.090 So there it is. We started with "Say Hello". 03:22.360 --> 03:24.400 Then we replaced "Hello" with "Goodbye". 03:26.550 --> 03:28.950 And again, we can use iterators. 03:32.560 --> 03:38.710 So we have a range of iterators, so we say that, everything in this half-open range, we want to 03:38.710 --> 03:39.190 replace. 03:39.760 --> 03:44.980 So in this case, we started with the first element, then everything up to, but not including, first 03:44.980 --> 03:46.120 element plus three. 03:46.810 --> 03:47.950 So that is the fourth element. 03:48.310 --> 03:50.290 So we are replacing everything before that. 03:51.190 --> 03:56.500 So we are replacing the first three elements, and then we are replacing them with "Wave". 04:01.290 --> 04:02.250 So there we are. 04:02.580 --> 04:05.820 We are going to replace the first three elements with "Wave". 04:09.470 --> 04:13.010 So we started out with "Say Goodbye", and now we are saying "Wave Goodbye". 04:18.780 --> 04:23.370 And finally, if we want to replace all the characters in the string with something else, we can do 04:23.450 --> 04:26.040 it in a single operation with "assign". 04:26.910 --> 04:30.870 So we just put the argument that we want to replace all the characters with. 04:33.440 --> 04:36.830 So we have "Hello", and we are going to replace all the characters with "Goodbye". 04:38.390 --> 04:39.170 And there we are. 04:40.280 --> 04:42.040 Okay, so that's it for this video. 04:42.050 --> 04:43.310 It's time for me to "say goodbye"! 04:43.820 --> 04:44.930 I'll see you again next time. 04:44.930 --> 04:47.180 But meanwhile, keep coding!