WEBVTT 00:00.320 --> 00:08.600 So far, every single example or statement that we've learned, we did the work in one single file. 00:08.630 --> 00:15.980 Now, this would be pretty hard to maintain in any project that has more significant size. 00:16.010 --> 00:22.130 That's why typically you would like to distribute your PHP code across multiple files. 00:22.160 --> 00:28.880 Now then you would need to somehow make sure that those files work together. 00:28.880 --> 00:36.470 So as you already know, PHP is not a compiled language, so every single time you'd like to use some 00:36.470 --> 00:39.800 code from another file, you need to load it. 00:39.800 --> 00:46.700 And in this video we're going to learn about two instructions or actually four instructions that let 00:46.700 --> 00:47.600 you do that. 00:47.600 --> 00:51.590 Load other PHP files and code inside them. 00:51.590 --> 00:55.010 They are called include and require. 00:55.040 --> 00:59.510 And for that let's create another folder first. 00:59.510 --> 01:05.120 Let's call it require and only then we're going to create some files inside. 01:07.480 --> 01:15.100 For this example, let's just use um, quite typical use case of storing the configuration in a separate 01:15.100 --> 01:15.910 file. 01:16.000 --> 01:25.600 Let me create a config.php file that will just store our configuration. 01:25.600 --> 01:29.620 And other than that let's create a main PHP file. 01:29.620 --> 01:32.530 Which job would be to run something. 01:33.010 --> 01:35.350 So let me jump back to the config file. 01:35.350 --> 01:39.550 And here let's just store some configuration options. 01:39.580 --> 01:41.590 Obviously that's all made up. 01:41.590 --> 01:43.150 We are just having an example. 01:43.150 --> 01:52.150 So maybe we would like to connect to a database so we can start the database host and the database user. 01:54.430 --> 01:56.860 Now let's jump to the main PHP file. 01:56.860 --> 02:01.570 So this file is to Bo is supposed to do something important. 02:01.570 --> 02:06.130 And we just want to keep the configuration separate. 02:06.130 --> 02:13.430 You know, not to have files that are excessively big without a reason. 02:13.430 --> 02:21.830 If we can divide the code into different files with some specific purpose, why won't we do that? 02:21.980 --> 02:30.470 So here, let's say I'd like to connect to the database, but obviously we're just gonna simulate that. 02:30.470 --> 02:41.510 Now in this example I will just output the db host and the db user variables. 02:43.370 --> 02:52.610 And if I now go to this require folder and I try to run the main PHP file, well we've got errors that 02:52.610 --> 02:54.650 we've got undefined variables. 02:54.680 --> 02:56.120 Now obviously that's the case. 02:56.120 --> 03:02.480 Those variables are not defined here but they are defined in this config PHP file. 03:02.510 --> 03:11.720 Let's see how can we get this file to be included inside our main file, which contains our app logic. 03:12.740 --> 03:22.330 So the first way is to just include the file using the include statement, where you just need to add 03:22.330 --> 03:25.390 the or provide the relative path to this file. 03:25.390 --> 03:28.030 So in it is in the current directory. 03:28.030 --> 03:30.580 So I can just do php config. 03:30.820 --> 03:40.720 PHP and if I run this script again now we have the values of both variables which is localhost and route. 03:44.080 --> 03:48.340 Now another way is to use the require stand statement. 03:48.340 --> 03:51.670 If I run this script, this seems to be the same. 03:51.670 --> 03:53.500 Now there has to be a difference. 03:53.500 --> 03:56.740 Otherwise those two statements would not exist. 03:56.740 --> 04:04.300 So the difference is that with the include statement, if the included file won't exist, we might get 04:04.300 --> 04:12.370 a warning, but the script will try to continue to run, but with require the application would just 04:12.370 --> 04:13.210 crash. 04:13.210 --> 04:19.690 So let me rename the config file to something else so we make sure it wouldn't be found. 04:19.690 --> 04:23.400 And first let's see the include way. 04:23.670 --> 04:27.570 So let's rerun the script again. 04:27.960 --> 04:36.900 And as I've said, we've got the PHP warning that the file could not be found and nothing really happens. 04:36.900 --> 04:43.320 We got more warnings that the variables also weren't found, they weren't defined. 04:43.320 --> 04:51.540 And if you have the warnings disabled in PHP, which is possible, the script will just run. 04:51.540 --> 04:57.840 It's obviously wrong and it won't do whatever it needs to do, but it will try to, you know, somehow 04:57.840 --> 05:02.760 cope with the situation and do whatever is possible. 05:02.790 --> 05:06.030 Now it's different with require. 05:07.590 --> 05:11.250 Now let me clear the console and run it again. 05:11.310 --> 05:15.690 So here we get a fatal error. 05:15.690 --> 05:19.530 So we couldn't open this config PHP file. 05:19.530 --> 05:22.890 And basically the script stop at this point. 05:23.160 --> 05:30.830 So you can see that there are no warnings about undefined variables in this echo statement, because 05:30.860 --> 05:35.510 stopping at this point means that this line wasn't even executed. 05:35.510 --> 05:37.400 We stopped at this line. 05:37.400 --> 05:39.020 The file wasn't found. 05:39.050 --> 05:40.850 It's a critical error. 05:40.850 --> 05:42.710 So the script has stopped. 05:42.740 --> 05:50.480 Now, when you need to include crucial information like the configuration for a database, it's obviously 05:50.480 --> 05:56.660 much better idea to use require because you know it is essential for the script to run. 05:58.130 --> 06:04.610 Now let's rename this file back to this original config php name so it works again. 06:06.350 --> 06:10.730 Now the require and include are just normal statements. 06:10.730 --> 06:18.440 You can use them how many times you want, and sometimes this might have some unexpected effects, because 06:18.440 --> 06:25.700 in those PHP files you not only can have the configuration and some variables defined, you might also 06:25.700 --> 06:31.760 have some code running and requiring this file two times would then cause. 06:31.760 --> 06:41.760 This included required code to run twice, and for such cases you just might want to use require ones 06:41.760 --> 06:48.750 or include ones well, they are the same as require and include respectively. 06:48.750 --> 06:56.100 They just make sure that if you've included or required certain file already, it won't happen again, 06:56.100 --> 07:00.240 even if there is an instruction that tries to do that. 07:00.330 --> 07:08.010 So typically it is safer to rely on either require one's own or include ones. 07:08.010 --> 07:12.150 And as a quick reminder, so you remember the main point. 07:12.150 --> 07:20.280 The main difference between require and include include will let you run your script even if the file 07:20.280 --> 07:27.960 doesn't exist or couldn't be found for any reason, and require will just crash if the file can't be 07:27.960 --> 07:28.710 found. 07:28.710 --> 07:31.080 So use require for any. 07:31.110 --> 07:39.540 Let's call it mission critical files that maybe have configuration to the database or any other credentials.