WEBVTT 00:00.750 --> 00:02.010 When working with strings. 00:02.040 --> 00:05.160 Another common task is to remove a prefix. 00:05.160 --> 00:15.440 Consider a URL with the common prefix https and we want to remove this prefix so we can focus on just 00:15.450 --> 00:21.270 a part of the URL that the users need to enter into an address bar. 00:21.300 --> 00:22.920 Here's how you do that. 00:22.950 --> 00:26.940 Firstly, we will enter the auxiliary URL. 00:27.300 --> 00:31.800 URL and here we will enter. 00:32.680 --> 00:44.380 Http oxley.com and is actually Udemy URL but in this case Udemy url will be https. 00:44.410 --> 00:44.980 Right. 00:45.010 --> 00:46.780 It will have different. 00:47.710 --> 00:48.280 Perfect. 00:50.180 --> 00:53.300 And here we will udemy.com. 00:54.050 --> 00:55.010 Now. 00:57.810 --> 00:59.010 Let's do this. 00:59.040 --> 00:59.640 Oxalate. 00:59.640 --> 01:02.090 That oxalate equals oxalate. 01:02.760 --> 01:07.590 Remove prefix http http. 01:08.880 --> 01:09.450 Here. 01:09.450 --> 01:13.710 And for Udemy we will use different https, right? 01:15.620 --> 01:18.080 What Udemy URL. 01:19.210 --> 01:21.730 Udemy url dot remove prefix. 01:21.790 --> 01:23.320 Http here. 01:23.350 --> 01:33.280 So if we do this and let's print this after that print url and print Udemy url. 01:33.280 --> 01:34.000 That's it. 01:34.860 --> 01:36.540 Now let's run this. 01:36.960 --> 01:38.190 And as you can see here. 01:38.190 --> 01:47.940 Yes, excellent Comet changed, but all udemy.com is left unchanged because we need to add s here to 01:47.940 --> 01:49.610 completely fix this. 01:49.620 --> 01:52.920 And here, as you can see here, com is changed. 01:52.920 --> 02:02.880 So you enter the name of the variable followed by a dot and then the method remove prefix. 02:03.210 --> 02:09.210 So inside the parentheses enter the prefix you want to remove from the original string. 02:10.380 --> 02:16.320 So like the methods for removing whitespace remove prefix leaves the original string unchanged. 02:16.350 --> 02:24.510 So if you want to keep the new value with the prefix removed, either reassign to the original variable 02:24.690 --> 02:28.230 like I did here or assign it to a new variable. 02:28.710 --> 02:34.920 So when you see a URL in an address bar, uh, the http. 02:36.010 --> 02:38.290 This part isn't shown. 02:38.320 --> 02:43.660 The browser is probably using a method like remove prefix. 02:44.050 --> 02:45.460 Behind the scenes. 02:46.490 --> 02:53.720 Let's actually now learn about how to avoid syntax errors with strings. 02:53.780 --> 03:01.400 So one kind of error that you might see with some regularity is a syntax error. 03:01.430 --> 03:09.260 A syntax error occurs when Python doesn't recognize a section of your program as valid python code. 03:09.290 --> 03:15.890 For example, if you use apostrophe within a single quotes, you will produce error. 03:15.920 --> 03:22.700 This happens because Python interprets everything between the first single quote and the apostrophe 03:22.730 --> 03:23.900 as a string. 03:23.930 --> 03:27.590 So it then tries to interpret the rest of. 03:29.620 --> 03:34.810 Uh, interpret the rest of the text as a python code, which causes errors. 03:34.810 --> 03:39.700 So here's how you use the single and the double quotes correctly. 03:39.850 --> 03:43.000 So now we will enter this here. 03:43.120 --> 03:46.210 Now I will share this quotes with you. 03:46.210 --> 03:47.050 So. 03:49.060 --> 03:51.070 Example one. 03:52.790 --> 03:53.270 Here. 03:55.060 --> 03:55.990 Now. 04:13.430 --> 04:14.360 I'll do this. 04:14.640 --> 04:14.900 That's. 04:16.630 --> 04:17.830 And now. 04:19.140 --> 04:19.560 Um. 04:25.970 --> 04:27.860 Now, let's actually write this here. 04:28.340 --> 04:33.110 As we said, the message here one. 04:33.950 --> 04:40.200 Oh, one of the one of the titans of. 04:41.600 --> 04:46.580 Fighters strength is its diverse. 04:53.700 --> 04:54.900 Yeah, it's. 04:55.080 --> 04:56.580 Is it? 04:58.040 --> 04:59.270 Diverse. 05:01.400 --> 05:02.300 Community. 05:03.240 --> 05:03.900 Here. 05:03.900 --> 05:05.550 We will print this message. 05:06.060 --> 05:06.810 Message? 05:08.610 --> 05:09.990 I was, actually. 05:13.320 --> 05:16.710 Now we will create a text file here and. 05:19.030 --> 05:19.690 Here. 05:19.690 --> 05:30.160 The first rope appears inside a set of double quotes so the python interpreter has no trouble executing 05:30.160 --> 05:31.720 and running this command. 05:31.720 --> 05:33.760 So it's okay for now. 05:34.300 --> 05:37.480 However, if you use single quotes. 05:38.330 --> 05:43.760 Python cannot identify where the string should end. 05:44.060 --> 05:50.300 So here we will get an error and this code will not compile because as you can see, we have an error 05:50.300 --> 05:51.650 in line one message. 05:51.810 --> 05:56.020 The python's strength is its diverse community. 05:56.030 --> 05:57.830 Invalid syntax. 05:59.790 --> 06:03.330 And here you will see this error something. 06:03.540 --> 06:11.130 And in the output you can see that error occurs right after the final single quote here. 06:13.690 --> 06:20.740 And this syntax error indicates that the interpreter doesn't recognize something in the code as valid 06:20.770 --> 06:21.250 python code. 06:21.280 --> 06:21.660 Right. 06:21.670 --> 06:28.780 And it thinks the problem might be a string that's not quoted correctly and the errors can. 06:29.680 --> 06:34.590 From a variety of sources, and I will point out some common ones as they arise. 06:34.600 --> 06:40.060 So you might see syntax errors often as you learn to write proper python code. 06:40.420 --> 06:45.160 So syntax errors are also the least specific kinds of errors. 06:45.160 --> 06:51.130 So they can be difficult and frustrating to identify and correct. 06:51.130 --> 06:59.140 So if you get stuck on a particular step or an error, you can ask me and I will answer them immediately.