Basic PHP Tutorial 16: Include and Require

Key Takeaways

hello and welcome to the 16th basic higher python i knew i was going to do that basic php tutorial uh in this tutorial uh we're gonna be discussing the include and require um commands and basically what they're gonna do is they pretty much do the same thing but if they can't do it that's where they defer so the include is going to call for a file to be included if it can't be included everything will still run require on the other hand will require that uh file whatever to be included so to speak and if not then it will it will cease to run so um but the actual command to do it is the same and so in this sense what we're going to do is i've already got this header.php file it says header two but it's actually header not quite sure why it's doing maybe because i have another header file or something in this temp folder but regardless it is corresponding to the header.php so for header.php we're just going to do h1 and this is the website title and uh in fact instead of this is the website title let's call this um php or welcome to my php tutorials okay that'll be our header we'll save that and we'll upload that to the server so if we pop over to um if we pop to this uh we see this is the page this is what's included with header it's just you know h1 with header one tags and we want that on this page so the way that we do that is we'll pop over here and you just say include header.php now if uh input it in quotes if it is located in the same directory then you put it there otherwise you know you start using these um oops it'll go within here like that if it's in like one prior directory if it's in another prior directory we'll do that and so on but for now it's actually in the um the same directory so we'll just leave that there and now we're going to say we're just going to echo out some regular text hello regular text and we'll save this and we'll run this and when we refresh um oh we forgot our semicolon of course now you see that we've included the rules for our really a header file and so the reason you'd want to do this is over time if you have a website or if you've ever visited a website in your life you probably notice that the top of the website is about the same no matter what page you go to now if this was hard coded um as in like typed out every page like say um this website wanted to have like a little bit of a facelift and use a new banner or something like that they would have to like go through by hand and change every single um pages header and that would be like really tedious so instead what you do is you just have include header.php at the top of the script and what it'll do is we'll just include whatever the header is so if you wanted to say um you know what i like php that's cool and tutorials what if uh what if we wanted to do like we were like well dang you know now we're we're like strictly like php video tutorials right like you're like dang that's like a way better way to describe our site so so we'll do uh welcome to my php video tutorials and say you have if you had you know 50 pages you don't have to edit this page at all you just edit the header page and so when you save that header page um we'll come back over here and now it's video tutorials and so if you had like 50 different pages you would be able to do this like really really quick instead of having to go through and edit them and just as a quick aside since it is here we can say require header.php and we'll upload that and refresh and you know it's still there so it's still working so it doesn't really matter which one you use if it's there but if you don't want the page to break if it can't get that file then you just say include so like if you were including a php page or a script that had like an integral function to the entire page and you couldn't seem to get that you would want to use that like require if it's integral to the page working you would want to use a require that way you're not going to continue running through a bunch of code when you don't have the information you really need right and you would want to have some sort of error code or something like that and then with this another thing you can do is see say like we did this what if we did two includes so we include the header file twice what happens then well if this would upload hold up so we pop over here we run it and as you can see you know it's included it and used it twice um now we can get rid of that one um so now uh the heck was i going to show you all right right what you can use is these two there's another a variation of these in functions where you can say include underscore uh once and now let's save it replay and now you see even though um we called it twice it's only been displayed once because what this include once does is it asks the question has this already been included if so never mind and as you can see it has already been included therefore it did not include this one same thing with required it could be require once like so and boy i wonder what happens if we use require ones because it hasn't been required it's been included so now what oh man the suspense it's killing me it is just killing me and it only runs once so hopefully not too many of you guys got killed by the suspense um so anyways that's the include and require functions as always thank you for watching and until next time