Beginner PHP Tutorial - 63 - Using the Header to Force Page Redirect Video Lecture | PHP for Absolute Beginners: From Novice to PHP Master - Web Development

hello this is Alex from PHP academy' org
and this is a video tutorial for the new
Boston in this video tutorial we are
going to be looking at the headers
function or the header function in PHP
so to modify the headers that are sent
to our browser now why would we need to
modify headers that are sent to our
browser now there are lots of different
reasons for this you may want to say
enable or disable caching of pages you
also might want to change the document
type so you might want to change it to
say a JPEG image or a PNG image or
something like that in order to process
an image on a page if you were using say
the PHP GD library which is something
you can look at later however in this
tutorial because we're just talking
about functionality of this we're going
to be using this header function to
redirect our users to another page now
before we start it's really important to
let you know that the header function
which looks like this cannot be used
after output has been sent to a page so
for example if we have a header called
or some header tags this is a HTML
output therefore we're using PHP
afterwards to using the header function
however this won't work
because we've already sent data to the
page so if you are to use the header
function you either have to use it after
our content or we need to talk about
output buffering and starting output
buffering on a page which is another
tutorial so where you can have a look at
that in regards to headers so let's just
say we have a PHP a blank PHP page I'm
going to create a variable called true
in fact I'm going to create a variable
called re-direct which is equal to true
now I'm going to create a simple if
statement to redirect us to a specific
page
if this variable is true so obviously
this is an example but later on if you
have let's say want to log a user in or
log user out you might want to redirect
them back to a specific page so we start
the header function like this and inside
we specify the location and to do this
we always use the predefined text
location and then a colon and after this
we specify the page we want to read
directly user to so I'm going to say
redirect page equals HTTP colon forward
slash forward slash Google Code UK so
now what I can do after this is I can
append redirect page so this is
essentially the same as typing header
and then the location inside and then
writing writing it like that however I'm
using variables just so we can get used
to the idea that this page may change so
at the moment this this should redirect
us to Google as we enter the page so
let's refresh and you can see what
that's done is it redirected me straight
over to Google code at UK so let's
likely modify the script I want to say
if redirect equals true redirect the
user otherwise down so at the moment
redirect is equal to true but I can
change this to redirect equals false and
we can go back headers and we haven't
been redirected however if we were to
change this here to true I'm able to
redirect to a specific page then we
refresh and we are redirected so just by
demonstrating the use of the function
with regards to redirecting user you can
see that how useful it is in changing
page and
Meishan like I said now this is the this
is an example to redirect to user
however if you research this function um
enough and watch some of my other
tutorials as well because we will be
using this function later on you'll
understand that it's not just for for
redirecting a user it's actually just to
modify the header information with your
your client your browser so bear this
function in mind the location feature of
it is very important and it's a great
way to sort of quickly redirect your
user without using any meta tags so HTML
meta tags and just remember that we
can't have any output any HTML put
before this so I've created header tags
my page with the h1 tags now let's go
back and go to headers now we've got my
page displayed that's absolutely fine
but now we have a warning it says cannot
modify header information headers
already sent on line 8 so this is the
where we're getting the error you can
see this is like 8 but headers already
sent however if we were to have this
below here
we're already modifying the pages
headers so we're rescinding header
information but we're never going to get
to see this so what happens if you want
to have a page that already maybe has
some output but you need to redirect the
user at some point there's a simple
option and that's OB which stands for
output buffering and we'll discuss that
in another tutorial which will be the
next in after this