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<HTML
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>Variables from outside PHP</TITLE
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><A
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>Chapter 7. Variables</TD
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><DIV
CLASS="sect1"
><H1
CLASS="sect1"
><A
NAME="language.variables.external"
>Variables from outside PHP</A
></H1
><DIV
CLASS="sect2"
><H2
CLASS="sect2"
><A
NAME="language.variables.external.form"
>HTML Forms (GET and POST)</A
></H2
><P
>&#13;     When a form is submitted to a PHP script, any variables from that
     form will be automatically made available to the script by
     PHP. If the <A
HREF="configuration.html#ini.track-vars"
>track_vars</A
>
     configuration option is turned on, then these variables will be
     located in the associative arrays
     <TT
CLASS="varname"
>$HTTP_POST_VARS</TT
>,
     <TT
CLASS="varname"
>$HTTP_GET_VARS</TT
>, and/or
     <TT
CLASS="varname"
>$HTTP_POST_FILES</TT
>, according to the
     source of the variable in question.
    </P
><P
>&#13;     For more information on these variables, please read <A
HREF="language.variables.predefined.html"
>Predefined
     variables</A
>.
    </P
><P
>&#13;     <TABLE
WIDTH="100%"
BORDER="0"
CELLPADDING="0"
CELLSPACING="0"
CLASS="EXAMPLE"
><TR
><TD
><DIV
CLASS="example"
><A
NAME="AEN2830"
></A
><P
><B
>Example 7-1. Simple form variable</B
></P
><TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="100%"
><TR
><TD
><PRE
CLASS="programlisting"
>&#13;&#60;form action="foo.php" method="post"&#62;
    Name: &#60;input type="text" name="username"&#62;&#60;br&#62;
    &#60;input type="submit"&#62;
&#60;/form&#62;
      </PRE
></TD
></TR
></TABLE
></DIV
></TD
></TR
></TABLE
>
    </P
><P
>&#13;     When the above form is submitted, the value from the text input
     will be available in
     <TT
CLASS="varname"
>$HTTP_POST_VARS['username']</TT
>. If the <A
HREF="configuration.html#ini.register-globals"
>register_globals</A
>
     configuration directive is turned on, then the variable will also
     be available as <TT
CLASS="varname"
>$username</TT
> in the global scope.
    </P
><P
>&#13;     PHP also understands arrays in the context of form variables. You
     may, for example, group related variables together, or use this
     feature to retrieve values from a multiple select
     input:
    </P
><P
>&#13;     <TABLE
WIDTH="100%"
BORDER="0"
CELLPADDING="0"
CELLSPACING="0"
CLASS="EXAMPLE"
><TR
><TD
><DIV
CLASS="example"
><A
NAME="AEN2839"
></A
><P
><B
>Example 7-2. More complex form variables</B
></P
><TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="100%"
><TR
><TD
><PRE
CLASS="programlisting"
>&#13;&#60;form action="array.php" method="post"&#62;
    Name: &#60;input type="text" name="personal[name]"&#62;&#60;br&#62;
    Email: &#60;input type="text" name="personal[email]"&#62;&#60;br&#62;
    Beer: &#60;br&#62;
    &#60;select multiple name="beer[]"&#62;
        &#60;option value="warthog"&#62;Warthog
        &#60;option value="guinness"&#62;Guinness
        &#60;option value="stuttgarter"&#62;Stuttgarter Schwabenbru
        &#60;/select&#62;
    &#60;input type="submit"&#62;
&#60;/form&#62;
      </PRE
></TD
></TR
></TABLE
></DIV
></TD
></TR
></TABLE
>
    </P
><P
>&#13;     In PHP 3, the array form variable usage is limited to
     single-dimensional arrays. In PHP 4, no such restriction applies.
    </P
><DIV
CLASS="sect3"
><H3
CLASS="sect3"
><A
NAME="AEN2843"
>IMAGE SUBMIT variable names</A
></H3
><P
>&#13;      When submitting a form, it is possible to use an image instead
      of the standard submit button with a tag like:</P
><DIV
CLASS="informalexample"
><A
NAME="AEN2846"
></A
><P
></P
><TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="100%"
><TR
><TD
><PRE
CLASS="programlisting"
>&#13;&#60;input type=image src="image.gif" name="sub"&#62;
      </PRE
></TD
></TR
></TABLE
><P
></P
></DIV
><P
>&#13;      When the user clicks somewhere on the image, the accompanying
      form will be transmitted to the server with two additional
      variables, sub_x and sub_y. These contain the coordinates of the
      user click within the image.  The experienced may note that the
      actual variable names sent by the browser contains a period
      rather than an underscore, but PHP converts the period to an
      underscore automatically.
     </P
></DIV
></DIV
><DIV
CLASS="sect2"
><H2
CLASS="sect2"
><A
NAME="language.variables.external.cookies"
>HTTP Cookies</A
></H2
><P
>&#13;     PHP transparently supports HTTP cookies as defined by <A
HREF="http://www.netscape.com/newsref/std/cookie_spec.html"
TARGET="_top"
>Netscape's Spec</A
>.  Cookies are a
     mechanism for storing data in the remote browser and thus
     tracking or identifying return users.  You can set cookies using
     the <B
CLASS="function"
>SetCookie()</B
> function.  Cookies are part of
     the HTTP header, so the SetCookie function must be called before
     any output is sent to the browser.  This is the same restriction
     as for the <B
CLASS="function"
>Header()</B
> function.  Any cookies
     sent to you from the client will automatically be turned into a
     PHP variable just like GET and POST method data.</P
><P
>&#13;     If you wish to assign multiple values to a single cookie, just
     add <I
CLASS="emphasis"
>[]</I
> to the cookie name.  For
     example:
    </P
><DIV
CLASS="informalexample"
><A
NAME="AEN2857"
></A
><P
></P
><TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="100%"
><TR
><TD
><PRE
CLASS="programlisting"
>&#13;SetCookie ("MyCookie[]", "Testing", time()+3600);
     </PRE
></TD
></TR
></TABLE
><P
></P
></DIV
><P
>&#13;     Note that a cookie will replace a previous cookie by the same
     name in your browser unless the path or domain is different.  So,
     for a shopping cart application you may want to keep a counter
     and pass this along.  i.e.
    </P
><TABLE
WIDTH="100%"
BORDER="0"
CELLPADDING="0"
CELLSPACING="0"
CLASS="EXAMPLE"
><TR
><TD
><DIV
CLASS="example"
><A
NAME="AEN2860"
></A
><P
><B
>Example 7-3. SetCookie Example</B
></P
><TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="100%"
><TR
><TD
><PRE
CLASS="programlisting"
>&#13;$Count++;
SetCookie ("Count", $Count, time()+3600);
SetCookie ("Cart[$Count]", $item, time()+3600);
     </PRE
></TD
></TR
></TABLE
></DIV
></TD
></TR
></TABLE
></DIV
><DIV
CLASS="sect2"
><H2
CLASS="sect2"
><A
NAME="language.variables.external.environment"
>Environment variables</A
></H2
><P
>&#13;     PHP automatically makes environment variables available as normal
     PHP variables.
     
     <DIV
CLASS="informalexample"
><A
NAME="AEN2866"
></A
><P
></P
><TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="100%"
><TR
><TD
><PRE
CLASS="programlisting"
>&#13;echo $HOME;  /* Shows the HOME environment variable, if set. */
      </PRE
></TD
></TR
></TABLE
><P
></P
></DIV
>
    </P
><P
>&#13;     Since information coming in via GET, POST and Cookie mechanisms
     also automatically create PHP variables, it is sometimes best to
     explicitly read a variable from the environment in order to make
     sure that you are getting the right version.  The
     <A
HREF="function.getenv.html"
><B
CLASS="function"
>getenv()</B
></A
> function can be used for this.  You
     can also set an environment variable with the
     <A
HREF="function.putenv.html"
><B
CLASS="function"
>putenv()</B
></A
> function.
    </P
></DIV
><DIV
CLASS="sect2"
><H2
CLASS="sect2"
><A
NAME="AEN2871"
>Dots in incoming variable names</A
></H2
><P
>&#13;     Typically, PHP does not alter the names of variables when they
     are passed into a script. However, it should be noted that the
     dot (period, full stop) is not a valid character in a PHP
     variable name. For the reason, look at it:
     <TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="100%"
><TR
><TD
><PRE
CLASS="programlisting"
>&#13;$varname.ext;  /* invalid variable name */
     </PRE
></TD
></TR
></TABLE
>
     Now, what the parser sees is a variable named
     <TT
CLASS="varname"
>$varname</TT
>, followed by the string concatenation
     operator, followed by the barestring (i.e. unquoted string which
     doesn't match any known key or reserved words) 'ext'. Obviously,
     this doesn't have the intended result.
    </P
><P
>&#13;     For this reason, it is important to note that PHP will
     automatically replace any dots in incoming variable names with
     underscores.
    </P
></DIV
><DIV
CLASS="sect2"
><H2
CLASS="sect2"
><A
NAME="AEN2877"
>Determining variable types</A
></H2
><P
>&#13;     Because PHP determines the types of variables and converts them
     (generally) as needed, it is not always obvious what type a given
     variable is at any one time.  PHP includes several functions
     which find out what type a variable is. They are
     <A
HREF="function.gettype.html"
><B
CLASS="function"
>gettype()</B
></A
>, <A
HREF="function.is-long.html"
><B
CLASS="function"
>is_long()</B
></A
>,
     <A
HREF="function.is-double.html"
><B
CLASS="function"
>is_double()</B
></A
>, <A
HREF="function.is-string.html"
><B
CLASS="function"
>is_string()</B
></A
>,
     <A
HREF="function.is-array.html"
><B
CLASS="function"
>is_array()</B
></A
>, and
     <A
HREF="function.is-object.html"
><B
CLASS="function"
>is_object()</B
></A
>.
    </P
></DIV
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