The include() statement includes and evaluates
the specified file.
The documentation below also applies to require().
The two constructs are identical in every way except how they handle
failure. include() produces a
Warning while require()
results in a Fatal Error.
In other words, use require() if you want
a missing file to halt processing of the page. include() does
not behave this way, the script will continue regardless. Be sure to have an
appropriate include_path setting as well.
When a file is included, the code it contains inherits the
variable scope of the
line on which the include occurs. Any variables available at that line
in the calling file will be available within the called file, from that
point forward.
Example 12-3. Basic include() example vars.php
<?php
$color = 'green';
$fruit = 'apple';
?>
test.php
<?php
echo "A $color $fruit"; // A
include 'vars.php';
echo "A $color $fruit"; // A green apple
?> |
|
If the include occurs inside a function within the calling file,
then all of the code contained in the called file will behave as
though it had been defined inside that function. So, it will follow
the variable scope of that function.
Example 12-4. Including within functions <?php
function foo()
{
global $color;
include 'vars.php';
echo "A $color $fruit";
}
/* vars.php is in the scope of foo() so *
* $fruit is NOT available outside of this *
* scope. $color is because we declared it *
* as global. */
foo(); // A green apple
echo "A $color $fruit"; // A green
?> |
|
When a file is included, parsing drops out of PHP mode and
into HTML mode at the beginning of the target file, and resumes
again at the end. For this reason, any code inside the target
file which should be executed as PHP code must be enclosed within
valid PHP start
and end tags.
If "URL fopen wrappers"
are enabled in PHP (which they are in the default configuration),
you can specify the file to be included using an URL (via HTTP or
other supported wrapper - see Appendix I for a list
of protocols) instead of a local pathname. If the target server interprets
the target file as PHP code, variables may be passed to the included
file using an URL request string as used with HTTP GET. This is
not strictly speaking the same thing as including the file and having
it inherit the parent file's variable scope; the script is actually
being run on the remote server and the result is then being
included into the local script.
| Warning |
Windows
versions of PHP prior to PHP 4.3 do not
support accessing remote files via this function, even if
allow_url_fopen is enabled.
|
Example 12-5. include() through HTTP <?php
/* This example assumes that www.example.com is configured to parse .php *
* files and not .txt files. Also, 'Works' here means that the variables *
* $foo and $bar are available within the included file. */
// Won't work; file.txt wasn't handled by www.example.com as PHP
include 'http://www.example.com/file.txt?foo=1&bar=2';
// Won't work; looks for a file named 'file.php?foo=1&bar=2' on the
// local filesystem.
include 'file.php?foo=1&bar=2';
// Works.
include 'http://www.example.com/file.php?foo=1&bar=2';
$foo = 1;
$bar = 2;
include 'file.txt'; // Works.
include 'file.php'; // Works.
?> |
|
See also
Remote files,
fopen() and
file() for related
information.
Because include() and require()
are special language constructs, you must enclose them within a statement
block if it's inside a conditional block.
Example 12-6. include() and conditional blocks <?php
// This is WRONG and will not work as desired.
if ($condition)
include $file;
else
include $other;
// This is CORRECT.
if ($condition) {
include $file;
} else {
include $other;
}
?> |
|
Handling Returns: It is possible to execute a return()
statement inside an included file in order to terminate processing in that
file and return to the script which called it. Also, it's possible to return
values from included files. You can take the value of the include call as
you would a normal function.
Note:
In PHP 3, the return may not appear inside a block unless it's
a function block, in which case the return() applies
to that function and not the whole file.
Example 12-7. include() and the return() statement return.php
<?php
$var = 'PHP';
return $var;
?>
noreturn.php
<?php
$var = 'PHP';
?>
testreturns.php
<?php
$foo = include 'return.php';
echo $foo; // prints 'PHP'
$bar = include 'noreturn.php';
echo $bar; // prints 1
?> |
|
$bar is the value 1 because the include
was successful. Notice the difference between the above examples. The first uses
return() within the included file while the other does not.
A few other ways to "include" files into variables are with
fopen(), file() or by using
include() along with
Output Control Functions.
See also require(), require_once(),
include_once(), readfile(),
virtual(), and
include_path.
