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php-manual-en-4.3.0-2mdk.noarch.rpm

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>Chapter 8. Variables</TD
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CLASS="sect1"
><H1
CLASS="sect1"
><A
NAME="language.variables.predefined"
></A
>Predefined variables</H1
><P
>&#13;    PHP provides a large number of predefined variables to any script
    which it runs. Many of these variables, however, cannot be fully
    documented as they are dependent upon which server is running, the
    version and setup of the server, and other factors. Some of these
    variables will not be available when PHP is run on the 
    <A
HREF="features.commandline.html"
>command line</A
>. 
    For a listing of these variables, please see the section on 
    <A
HREF="reserved.variables.html"
>Reserved Predefined Variables</A
>.
   </P
><DIV
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><TABLE
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><TR
><TD
ALIGN="CENTER"
><B
>Warning</B
></TD
></TR
><TR
><TD
ALIGN="LEFT"
><P
>&#13;     In PHP 4.2.0 and later, the default value for the PHP directive <A
HREF="configuration.directives.html#ini.register-globals"
>register_globals</A
> is 
     <SPAN
CLASS="emphasis"
><I
CLASS="emphasis"
>off</I
></SPAN
>. This is a major change in PHP.  Having 
     register_globals <SPAN
CLASS="emphasis"
><I
CLASS="emphasis"
>off</I
></SPAN
> affects the set of predefined 
     variables available in the global scope.  For example, to get 
     <TT
CLASS="varname"
>DOCUMENT_ROOT</TT
> you'll use 
     <TT
CLASS="varname"
>$_SERVER['DOCUMENT_ROOT']</TT
> instead of 
     <TT
CLASS="varname"
>$DOCUMENT_ROOT</TT
>, or <TT
CLASS="varname"
>$_GET['id']</TT
> from 
     the URL <TT
CLASS="literal"
>http://www.example.com/test.php?id=3</TT
> instead 
     of <TT
CLASS="varname"
>$id</TT
>, or <TT
CLASS="varname"
>$_ENV['HOME']</TT
> instead of 
     <TT
CLASS="varname"
>$HOME</TT
>.
    </P
><P
>&#13;     For related information on this change, read the configuration entry for 
     <A
HREF="configuration.directives.html#ini.register-globals"
>register_globals</A
>, the security 
     chapter on <A
HREF="security.registerglobals.html"
>Using Register Globals
     </A
>, as well as the PHP <A
HREF="http://www.php.net/release_4_1_0.php"
TARGET="_top"
>4.1.0
     </A
> and <A
HREF="http://www.php.net/release_4_2_0.php"
TARGET="_top"
>4.2.0</A
> Release 
     Announcements.
    </P
><P
>&#13;     Using the available PHP Reserved Predefined Variables, like the 
     <A
HREF="language.variables.predefined.html#language.variables.superglobals"
>superglobal arrays</A
>, 
     is preferred.
    </P
></TD
></TR
></TABLE
></DIV
><P
>&#13;    From version 4.1.0 onward, PHP provides an additional set of predefined arrays
    containing variables from the web server (if applicable), the
    environment, and user input. These new arrays are rather special
    in that they are automatically global--i.e., automatically
    available in every scope. For this reason, they are often known as
    'autoglobals' or 'superglobals'. (There is no mechanism in PHP for
    user-defined superglobals.) The superglobals are listed below;
    however, for a listing of their contents and further discussion on
    PHP predefined variables and their natures, please see the section
    <A
HREF="reserved.variables.html"
>Reserved Predefined Variables</A
>.  
    Also, you'll notice how the older predefined variables 
    (<TT
CLASS="varname"
>$HTTP_*_VARS</TT
>) still exist.
   </P
><DIV
CLASS="note"
><BLOCKQUOTE
CLASS="note"
><P
><B
>Variable variables: </B
>
     Superglobals cannot be used as 
     <A
HREF="language.variables.variable.html"
>variable variables</A
>.
    </P
></BLOCKQUOTE
></DIV
><P
>&#13;    If certain variables in <A
HREF="configuration.directives.html#ini.variables-order"
>variables_order</A
> are not set, their
    appropriate PHP predefined arrays are also left empty.
   </P
><P
></P
><DIV
CLASS="variablelist"
><P
><B
>PHP Superglobals</B
></P
><DL
><DT
><A
HREF="reserved.variables.html#reserved.variables.globals"
>$GLOBALS</A
></DT
><DD
><P
>&#13;       Contains a reference to every variable which is currently
       available within the global scope of the script. The keys of
       this array are the names of the global variables.
       <TT
CLASS="varname"
>$GLOBALS</TT
> has existed since PHP 3.
      </P
></DD
><DT
><A
HREF="reserved.variables.html#reserved.variables.server"
>$_SERVER</A
></DT
><DD
><P
>&#13;       Variables set by the web server or otherwise directly related
       to the execution environment of the current script. Analogous
       to the old <TT
CLASS="varname"
>$HTTP_SERVER_VARS</TT
> array (which is
       still available, but deprecated).
      </P
></DD
><DT
><A
HREF="reserved.variables.html#reserved.variables.get"
>$_GET</A
></DT
><DD
><P
>&#13;       Variables provided to the script via HTTP GET. Analogous to the
       old <TT
CLASS="varname"
>$HTTP_GET_VARS</TT
> array (which is still
       available, but deprecated).
      </P
></DD
><DT
><A
HREF="reserved.variables.html#reserved.variables.post"
>$_POST</A
></DT
><DD
><P
>&#13;       Variables provided to the script via HTTP POST. Analogous to the
       old <TT
CLASS="varname"
>$HTTP_POST_VARS</TT
> array (which is still
       available, but deprecated).
      </P
></DD
><DT
><A
HREF="reserved.variables.html#reserved.variables.cookies"
>$_COOKIE</A
></DT
><DD
><P
>&#13;       Variables provided to the script via HTTP cookies. Analogous to
       the old <TT
CLASS="varname"
>$HTTP_COOKIE_VARS</TT
> array (which is
       still available, but deprecated).
      </P
></DD
><DT
><A
HREF="reserved.variables.html#reserved.variables.files"
>$_FILES</A
></DT
><DD
><P
>&#13;       Variables provided to the script via HTTP post file
       uploads. Analogous to the old
       <TT
CLASS="varname"
>$HTTP_POST_FILES</TT
> array (which is still
       available, but deprecated). See <A
HREF="features.file-upload.html#features.file-upload.post-method"
>POST method
        uploads</A
> for more information.
      </P
></DD
><DT
><A
HREF="reserved.variables.html#reserved.variables.environment"
>$_ENV</A
></DT
><DD
><P
>&#13;       Variables provided to the script via the environment. Analogous
       to the old <TT
CLASS="varname"
>$HTTP_ENV_VARS</TT
> array (which is
       still available, but deprecated).
      </P
></DD
><DT
><A
HREF="reserved.variables.html#reserved.variables.request"
>$_REQUEST</A
></DT
><DD
><P
>&#13;       Variables provided to the script via any user input mechanism,
       and which therefore cannot be trusted. The presence and order 
       of variable inclusion in this array is defined according to the <A
HREF="configuration.directives.html#ini.variables-order"
>variables_order</A
>
       configuration directive. This array has no direct analogue in
       versions of PHP prior to 4.1.0.  See also 
       <A
HREF="function.import-request-variables.html"
><B
CLASS="function"
>import_request_variables()</B
></A
>.
      </P
><DIV
CLASS="note"
><BLOCKQUOTE
CLASS="note"
><P
><B
>Note: </B
>
        When running on the <A
HREF="features.commandline.html"
>command line
        </A
>, this will <SPAN
CLASS="emphasis"
><I
CLASS="emphasis"
>not</I
></SPAN
> include the 
        <TT
CLASS="varname"
>argv</TT
> and <TT
CLASS="varname"
>argc</TT
> entries; these are 
        present in the <TT
CLASS="varname"
>$_SERVER</TT
> array.
       </P
></BLOCKQUOTE
></DIV
></DD
><DT
><A
HREF="reserved.variables.html#reserved.variables.session"
>$_SESSION</A
></DT
><DD
><P
>&#13;       Variables which are currently registered to a script's
       session. Analogous to the old
       <TT
CLASS="varname"
>$HTTP_SESSION_VARS</TT
> array (which is still
       available, but deprecated). See the <A
HREF="ref.session.html"
>Session handling functions</A
> section
       for more information.
      </P
></DD
></DL
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