   #PHP Manual Control Structures require require_once

                 PHP Manual
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include()

   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 11-3. 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 11-4. 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 4.3.0 do not support accessing
   remote files via this function, even if allow_url_fopen is enabled.

   Example 11-5. 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 11-6. 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 11-7. 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.

     Note: Because this is a language construct and not a function, it
     cannot be called using variable functions

   See also require(), require_once(), include_once(), readfile(),
   virtual(), and include_path.
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