Question

I have a problem with the below:-

//index.php
<?php

define('PATH','Ajfit/');

/* Get all the required files and functions */
require(PATH . 'settings.inc.php');
require(PATH . 'inc/common.inc.php');

?>

//setting.inc.php
<?php
      $settings['language']='English';
?>

//inc/common.inc.php
<?php
      //global $settings, $lang, $_SESSION; //$setting = null????
      $language = $settings['language']; //$language is still null
?>

when i try and access the global variable $settings within common.inc.php it is set null even though i set the variable within setting.inc.php. If i debug, when i step out of setting.inc.php the $settings valiable is set within the index.php, however when i step into common.inc.php the $settings valiable is set to null.

Does anyone have any ideas?

Answer 1

Answer: In the inc/common.inc.php file, you don’t need to use the global keyword, the variable is already accessible. Using global redefines the variable, and is thus made null.

Explanation:

Variable Scope is the key here. The global keyword is only required when scope changes. The scope of regular files (including include()s) is all the same, so all of your variables are accessible by any php in the same scope, even if it comes from a different file.

An example of where you need to use global is inside of functions. The scope of a function is different than that of plain php, which is different from class scope, and so on.

Example:

//foo.php
  $foo = "bar";

  echo $foo; //prints "bar" since scope hasn't changed.

  function zoo() {
    echo $foo; //prints "" because of scope change.
  }

  function zoo2() {
    global $foo;
    echo $foo; //prints "bar" because $foo is recognized as in a higher scope.
  }

  include('bar.php');

//bar.php
  echo $foo; //prints "bar" because scope still hasn't changed.

  function zoo3() {
    echo $foo; //prints "" for the same reason as in zoo()
  }

  function zoo4() {
    global $foo;
    echo $foo; //prints "bar" for the same reason as in zoo2()
  }

More Information:

If you want more information on when to use global and when not to, check the php.net documentation on variable scope.