/xml/language/variables.xml

<?xml version="1.0" encoding="utf-8"?>

<!-- $Revision: 324974 $ -->

<!-- EN-Revision: 324522 Maintainer: HonestQiao Status: ready -->

<!-- Reviewed: no Maintainer: HonestQiao -->

<!-- CREDITS: dallas, Gregory, verdana -->

 <chapter xml:id="language.variables" xmlns="http://docbook.org/ns/docbook" xmlns:xlink="http://www.w3.org/1999/xlink">

  <title>??</title>



  <sect1 xml:id="language.variables.basics">

   <title>??</title>



   <simpara>

    PHP ????????????????????????????????

   </simpara>



   <para>

    ???? PHP

    ??????????????????????????????????????????????????????????????????????????'[a-zA-Z_\x7f-\xff][a-zA-Z0-9_\x7f-\xff]*'?

   </para>



   <note>

    <simpara>

     ???????? a-z?A-Z??? ASCII ??? 127 ? 255?0x7f-0xff??

    </simpara>

   </note>

   <note>

    <simpara>

     <literal>$this</literal> ????????????????

    </simpara>

   </note>

   

   &tip.userlandnaming;

   

   <para>

    ??????????<link linkend="ref.var">????</link>?

   </para>

   <para>

    <informalexample>

     <programlisting role="php">

<![CDATA[

<?php

$var = 'Bob';

$Var = 'Joe';

echo "$var, $Var";      // ?? "Bob, Joe"



$4site = 'not yet';     // ???????????

$_4site = 'not yet';    // ????????????

$i??is = 'mansikka';  // ???????????

?>

]]>

     </programlisting>

    </informalexample>

   </para>



   <para>

    ????????????????????????????????????????????????????????????????????????????????????????????????????????????????????<link linkend="language.expressions">???</link>???

   </para>

   <para>

    PHP ????????????????<link linkend="language.references">????</link>???????????????????“?????” ?? “??”???????????????????????????

   </para>

   <para>

    ????????????? &amp;

    ??????????????????????????????“My name is Bob”???

    <informalexample>

     <programlisting role="php">

<![CDATA[

<?php

$foo = 'Bob';              // ? 'Bob' ?? $foo

$bar = &$foo;              // ?? $bar ?? $foo

$bar = "My name is $bar";  // ?? $bar ??

echo $bar;

echo $foo;                 // $foo ??????

?>

]]>

     </programlisting>

    </informalexample>

   </para>



   <para>

    ???????????????????????????????

    <informalexample>

     <programlisting role="php">

<![CDATA[

<?php

$foo = 25;

$bar = &$foo;      // ?????

$bar = &(24 * 7);  // ??; ??????????



function test()

{

   return 25;

}



$bar = &test();    // ??

?>

]]>

     </programlisting>

    </informalexample>

   </para>

   <para>

    ??? PHP ?????????????????????????????????????????? - ???????????

    &false;????????????????????????????????????????????

   </para>

   <para>

    <example>

     <title>??????????</title>

     <programlisting role="php">

<![CDATA[

<?php

// Unset AND unreferenced (no use context) variable; outputs NULL

var_dump($unset_var);



// Boolean usage; outputs 'false' (See ternary operators for more on this syntax)

echo($unset_bool ? "true\n" : "false\n");



// String usage; outputs 'string(3) "abc"'

$unset_str .= 'abc';

var_dump($unset_str);



// Integer usage; outputs 'int(25)'

$unset_int += 25; // 0 + 25 => 25

var_dump($unset_int);



// Float/double usage; outputs 'float(1.25)'

$unset_float += 1.25;

var_dump($unset_float);



// Array usage; outputs array(1) {  [3]=>  string(3) "def" }

$unset_arr[3] = "def"; // array() + array(3 => "def") => array(3 => "def")

var_dump($unset_arr);



// Object usage; creates new stdClass object (see http://www.php.net/manual/en/reserved.classes.php)

// Outputs: object(stdClass)#1 (1) {  ["foo"]=>  string(3) "bar" }

$unset_obj->foo = 'bar';

var_dump($unset_obj);

?>

]]>

     </programlisting>

    </example>

   </para>

   <para>

    ???????????????????????????????????????????????????

    <link linkend="ini.register-globals">register_globals</link> ????????<link 

    linkend="security.globals">????</link>?????????????<link 

    linkend="errorfunc.constants.errorlevels.e-notice">E_NOTICE</link>????????????????????????<function>isset</function>

    ??????????????????????

   </para>

  </sect1>



  <sect1 xml:id="language.variables.predefined">

   <title>?????</title>



   <simpara>

    PHP ?????????????????????????????????????????????????????????????

    PHP ?<link linkend="features.commandline">???</link>?????????????????????????<link

    linkend="reserved.variables">?????</link>???

   </simpara>



   <warning>

    <simpara>

     PHP 4.2.0 ????????PHP ?? <link

     linkend="ini.register-globals">register_globals</link> ?????

     <emphasis>off</emphasis>??? PHP ????????? register_globals ???

     <emphasis>off</emphasis> ????????????????????????????

     <varname>DOCUMENT_ROOT</varname> ????????

     <varname>$_SERVER['DOCUMENT_ROOT']</varname> ??

     <varname>$DOCUMENT_ROOT</varname>??????

     <varname>$_GET['id']</varname> ??? <varname>$id</varname> ? URL

     <literal>http://www.example.com/test.php?id=3</literal> ???

     id ?????? <varname>$_ENV['HOME']</varname> ???

     <varname>$HOME</varname> ?????? HOME ???

    </simpara>

    <simpara>

     ?????????? <link

     linkend="ini.register-globals">register_globals</link>

     ?????????????<link

     linkend="security.globals">?? Register Globals</link>??? PHP

     <link xlink:href="&url.php.release4.1.0;">4.1.0</link> ?

     <link xlink:href="&url.php.release4.2.0;">4.2.0</link> ??????

    </simpara>

    <simpara>

     ?????? PHP ???????????<link

     linkend="language.variables.superglobals">?????</link>?

    </simpara>

   </warning>



   <simpara>

    ? PHP 4.1.0 ???PHP ???????????????????????? web

    ??????????????????????????????????????????????????????????????????????????autoglobals?????????superglobals???PHP

    ????????????????????????????????????????????

    PHP ???????????????????????<link

    linkend="reserved.variables">?????</link>??????????????????<varname>$HTTP_*_VARS</varname>??????&avail.register-long-arrays;

   </simpara>



   <note>

    <title>????</title>

    <para>

     ???????????<link linkend="language.variables.variable">????</link>?

    </para>

   </note>

    <note>

    <para>

     ???????? HTTP_*_VARS

     ??????????????????????????????????????

    </para>

   </note>



   <para>

    ???? <link linkend="ini.variables-order">variables_order</link>

    ??????????????? PHP ??????????

   </para>



  </sect1>





  <sect1 xml:id="language.variables.scope">

   <title>????</title>



   <simpara>

    ???????????????????????????????

    PHP ??????????????????????????

    include ? require ?????????

   </simpara>

   <informalexample>

    <programlisting role="php">

<![CDATA[

<?php

$a = 1;

include 'b.inc';

?>

]]>

    </programlisting>

   </informalexample>

   <simpara>

    ???? <varname>$a</varname> ???????

    <filename>b.inc</filename> ??????????????????????????????????????????????????????????????

   </simpara>



   <informalexample>

    <programlisting role="php">

<![CDATA[

<?php

$a = 1; /* global scope */



function Test()

{

    echo $a; /* reference to local scope variable */

}



Test();

?>

]]>

    </programlisting>

   </informalexample>



   <simpara>

    ?????????????? echo ??????????????

    <varname>$a</varname>????????????????????????

    PHP ?????? C ?????????? C

    ????????????????????????????????????????????????????????PHP

    ?????????????????global?

   </simpara>



   <sect2 xml:id="language.variables.scope.global">

    <title>global ???</title>

    <simpara>

     ??????? <literal>global</literal> ????

    </simpara>

    <para>

     <example>

      <title>?? global</title>

      <programlisting role="php">

<![CDATA[

<?php

$a = 1;

$b = 2;



function Sum()

{

    global $a, $b;



    $b = $a + $b;

}



Sum();

echo $b;

?>

]]>

      </programlisting>

     </example>

    </para>



    <simpara>

     ?????????“3”????????????

     <varname>$a</varname> ? <varname>$b</varname>???????????????????????????????????????????PHP ?????

    </simpara>



    <simpara>

     ?????????????????????? PHP ???

     <varname>$GLOBALS</varname> ?????????????

    </simpara>



    <para>

     <example>

      <title>?? <varname>$GLOBALS</varname> ?? global</title>

      <programlisting role="php">

<![CDATA[

<?php

$a = 1;

$b = 2;



function Sum()

{

    $GLOBALS['b'] = $GLOBALS['a'] + $GLOBALS['b'];

}



Sum();

echo $b;

?>

]]>

      </programlisting>

     </example>

    </para>



    <simpara>

      <varname>$GLOBALS</varname>

     ????????????????????????????????????<varname>$GLOBALS</varname>

     ??????????????? $GLOBALS ???<link

     linkend="language.variables.superglobals">?????</link>?????????????????

    </simpara>



    <para>

     <example>

      <title>??????????????</title>

      <programlisting role="php">

<![CDATA[

<?php

function test_global()

{

    // ??????????? "super"?????? 'global' ???????????????????

    global $HTTP_POST_VARS;



    echo $HTTP_POST_VARS['name'];



    // Superglobals ???????????????? 'global' ???Superglobals ?? PHP 4.1.0 ????

    echo $_POST['name'];

}

?>

]]>

      </programlisting>

     </example>

    </para>

   </sect2>



   <sect2 xml:id="language.variables.scope.static">

    <title>??????</title>



    <simpara>

     ?????????????<emphasis>????</emphasis>?static

     variable??????????????????????????????????????????????

    </simpara>



    <para>

     <example>

      <title>???????????</title>

      <programlisting role="php">

<![CDATA[

<?php

function Test()

{

    $a = 0;

    echo $a;

    $a++;

}

?>

]]>

      </programlisting>

     </example>

    </para>



    <simpara>

     ???????????????????

     <varname>$a</varname> ???? <literal>0</literal> ???

     &quot;0&quot;??????? <varname>$a</varname>++

     ?????????????????

     <varname>$a</varname> ?????????????????????????????

     <varname>$a</varname> ???????

    </simpara>



    <para>

     <example>

      <title>?????????</title>

      <programlisting role="php">

<![CDATA[

<?php

function test()

{

    static $a = 0;

    echo $a;

    $a++;

}

?>

]]>

      </programlisting>

     </example>

    </para>



    <simpara>

     ?????<varname>$a</varname>?????test()?????????? test() ??????

     <varname>$a</varname> ??????

    </simpara>



    <simpara>

     ???????????????????????????????????????????????????????????????????????????????????????

     10???????

     <varname>$count</varname> ????????

    </simpara>



    <para>

     <example>

      <title>?????????</title>

      <programlisting role="php">

<![CDATA[

<?php

function test()

{

    static $count = 0;



    $count++;

    echo $count;

    if ($count < 10) {

        test();

    }

    $count--;

}

?>

]]>

      </programlisting>

     </example>

    </para>



    <note>

     <para>

      ?????????????????????????????????????????

     </para>

     <para>

      <example>

       <title>??????</title>

       <programlisting role="php">

<![CDATA[

<?php

function foo(){

    static $int = 0;          // correct

    static $int = 1+2;        // wrong  (as it is an expression)

    static $int = sqrt(121);  // wrong  (as it is an expression too)



    $int++;

    echo $int;

}

?>

]]>

       </programlisting>

      </example>

     </para>

    </note>

   </sect2>



   <sect2 xml:id="language.variables.scope.references">

    <title>??????????</title>

    <simpara>

     ? Zend ?? 1 ?????? PHP4??????

     <link linkend="language.variables.scope.static">static</link> ?

     <link linkend="language.variables.scope.global">global</link>

     ???? <link linkend="language.references">references</link>

     ???????????????????

     <literal>global</literal>

     ????????????????????????????????????????????????????????

    </simpara>



    <informalexample>

     <programlisting role="php">

<![CDATA[

<?php

function test_global_ref() {

    global $obj;

    $obj = &new stdclass;

}



function test_global_noref() {

    global $obj;

    $obj = new stdclass;

}



test_global_ref();

var_dump($obj);

test_global_noref();

var_dump($obj);

?>

]]>

     </programlisting>

    </informalexample>



   &example.outputs;



    <screen>

NULL

object(stdClass)(0) {

}

    </screen>



    <simpara>

     ?????????

     <literal>static</literal> ???????????????

    </simpara>



    <informalexample>

     <programlisting role="php">

<![CDATA[

<?php

function &get_instance_ref() {

    static $obj;



    echo 'Static object: ';

    var_dump($obj);

    if (!isset($obj)) {

        // ????????????

        $obj = &new stdclass;

    }

    $obj->property++;

    return $obj;

}



function &get_instance_noref() {

    static $obj;



    echo 'Static object: ';

    var_dump($obj);

    if (!isset($obj)) {

        // ????????????

        $obj = new stdclass;

    }

    $obj->property++;

    return $obj;

}



$obj1 = get_instance_ref();

$still_obj1 = get_instance_ref();

echo "\n";

$obj2 = get_instance_noref();

$still_obj2 = get_instance_noref();

?>

]]>

     </programlisting>

    </informalexample>



   &example.outputs;



    <screen>

Static object: NULL

Static object: NULL



Static object: NULL

Static object: object(stdClass)(1) {

  ["property"]=>

  int(1)

}

    </screen>



    <simpara>

     ???????????????????????????

     <literal>&amp;get_instance_ref()</literal> ?????????<emphasis>??</emphasis>?

    </simpara>

   </sect2>

  </sect1>



  <sect1 xml:id="language.variables.variable">

   <title>????</title>



   <simpara>

     ?????????????????????????????????????????????????????????

   </simpara>



   <informalexample>

    <programlisting role="php">

<![CDATA[

<?php

$a = 'hello';

?>

]]>

    </programlisting>

   </informalexample>



   <simpara>

    ?????????????????????????????????????

    <emphasis>hello</emphasis> ??????????$???????????????????????

   </simpara>



   <informalexample>

    <programlisting role="php">

<![CDATA[

<?php

$$a = 'world';

?>

]]>

    </programlisting>

   </informalexample>



   <simpara>

    ?????????????<varname>$a</varname> ????“hello”??

    <varname>$hello</varname> ????“world”??????????

   </simpara>



   <informalexample>

    <programlisting role="php">

<![CDATA[

<?php

echo "$a ${$a}";

?>

]]>

    </programlisting>

   </informalexample>



   <simpara>

    ??????????????????

   </simpara>



   <informalexample>

    <programlisting role="php">

<![CDATA[

<?php

echo "$a $hello";

?>

]]>

    </programlisting>

   </informalexample>



   <simpara>

     ???????<computeroutput>hello world</computeroutput>?

   </simpara>



   <simpara>

    ???????????????????????????????

    <varname>$$a[1]</varname>

    ????????????

    <varname>$a[1]</varname>

    ????????????

    <varname>$$a</varname>

    ???????????????? [1]

    ????????????????????

    <varname>${$a[1]}</varname>????????

    <varname>${$a}[1]</varname>?

   </simpara>



   <warning>

    <simpara>

     ???? PHP ??????????<link

     linkend="language.variables.superglobals">?????</link>?????????

    </simpara>

   </warning>



  </sect1>



  <sect1 xml:id="language.variables.external">

   <title>?? PHP ?????</title>



   <sect2 xml:id="language.variables.external.form">

    <title>HTML ???GET ? POST?</title>



    <simpara>

     ???????? PHP

     ??????????????????????????????????

    </simpara>



    <para>

     <example>

      <title>????? HTML ??</title>

      <programlisting role="html">

<![CDATA[

<form action="foo.php" method="POST">

    Name:  <input type="text" name="username"><br />

    Email: <input type="text" name="email"><br />

    <input type="submit" name="submit" value="Submit me!" />

</form>

]]>

      </programlisting>

     </example>

    </para>



    <para>

     ?????????????????????? HTML

     ??????????

    </para>



    <para>

     <example>

      <title>?????? POST HTML ??????</title>

      <programlisting role="html">

<![CDATA[

<?php

// ? PHP 4.1.0 ???

   echo $_POST['username'];

   echo $_REQUEST['username'];

   

   import_request_variables('p', 'p_');

   echo $p_username;

// PHP 6??????? PHP 5.0.0 ????????????

// ?? register_long_arrays ?????



   echo $HTTP_POST_VARS['username'];



// ?? PHP ?? register_globals = on ???????

// PHP 4.2.0 ????? register_globals = off?

// ?????/???????



   echo $username;

?>

]]>

      </programlisting>

     </example>

    </para>

    <para>

     ?? GET ?????????????? GET ??????GET

     ????

     QUERY_STRING?URL ??“?”??????????????<literal>http://www.example.com/test.php?id=3</literal>

     ????? <varname>$_GET['id']</varname>

     ??? GET ?????

     <link linkend="reserved.variables.request">$_REQUEST</link> ?

     <function>import_request_variables</function>?

    </para>



    <note>

     <para>

      <link linkend="language.variables.superglobals">?????</link>?

      <varname>$_POST</varname> ?? <varname>$_GET</varname> ????

      PHP 4.1.0 ????

     </para>

    </note>



    <para>

     ?????? PHP 4.2.0 ?? <link

     linkend="ini.register-globals">register_globals</link>

     ?????

     <emphasis>on</emphasis>?PHP

     ????????????????????????

     <emphasis>off</emphasis>?

    </para>



    <note>

     <para>

      <link linkend="ini.magic-quotes-gpc">magic_quotes_gpc</link>

      ???????

      Get?Post ? Cookie ????????? (It's "PHP!") ??????

      (It\'s \"PHP!\")???????????????

      <function>addslashes</function>?<function>stripslashes</function> ?

      <link linkend="ini.magic-quotes-sybase">magic_quotes_sybase</link>?

     </para>

    </note>



    <simpara>

     PHP ?????????????????<link

     linkend="faq.html">??????</link>????????????????????????????????????????? POST ?????????????

    </simpara>



    <para>

     <example>

      <title>????????</title>

      <programlisting role="php">

<![CDATA[

<?php

if (isset($_POST['action']) && $_POST['action'] == 'submitted') {

    echo '<pre>';



    print_r($_POST);

    echo '<a href="'. $_SERVER['PHP_SELF'] .'">Please try again</a>';



    echo '</pre>';

} else {

?>

<form action="<?php echo $_SERVER['PHP_SELF']; ?>" method="post">

    Name:  <input type="text" name="personal[name]"><br />

    Email: <input type="text" name="personal[email]"><br />

    Beer: <br>

    <select multiple name="beer[]">

        <option value="warthog">Warthog</option>

        <option value="guinness">Guinness</option>

        <option value="stuttgarter">Stuttgarter Schwabenbr</option>

    </select><br />

    <input type="hidden" name="action" value="submitted" />

    <input type="submit" name="submit" value="submit me!" />

</form>

<?php

}

?>

]]>

      </programlisting>

     </example>

    </para>



     <sect3 xml:id="language.variables.external.form.submit">

     <title>IMAGE SUBMIT ???</title>



     <simpara>

      ?????????????????????????????????

     </simpara>



     <informalexample>

      <programlisting role="html">

<![CDATA[

<input type="image" src="image.gif" name="sub" />

]]>

      </programlisting>

     </informalexample>



     <simpara>

      ???????????????????????????????????

      sub_x ? sub_y???????????????????????????????????????????????????????

      sub.x ? sub.y??? PHP ????????????

     </simpara>

    </sect3>



   </sect2>



   <sect2 xml:id="language.variables.external.cookies">

    <title>HTTP Cookies</title>



    <simpara>

     PHP ????? <link

     xlink:href="&url.rfc;6265">RFC 6265</link>????

     HTTP cookies?Cookies

     ???????????????????????????????????

     <function>setcookie</function>

     ???? cookies?Cookies ?

     HTTP ???????????

     SetCookie ??????????????????????

     <function>header</function> ??????????Cookie

     ??????? cookie ??????????

     <varname>$_COOKIE</varname>?<varname>$HTTP_COOKIE_VARS</varname> ?

     <varname>$_REQUEST</varname>?????????

     <function>setcookie</function> ?????

    </simpara>



    <simpara>

     ??????????? cookie ???????????????

    </simpara>



    <informalexample>

     <programlisting role="php">

<![CDATA[

<?php

  setcookie("MyCookie[foo]", 'Testing 1', time()+3600);

  setcookie("MyCookie[bar]", 'Testing 2', time()+3600);

?>

]]>

     </programlisting>

    </informalexample>



    <simpara>

     ?????????? cookie??? MyCookie

     ????????????????????? cookie

     ???????????????

     <function>serialize</function> ?

     <function>explode</function>?

    </simpara>



    <simpara>

     ????????? cookie ??????????

     cookie??????????????????????????????????????

    </simpara>



    <example>

     <title>?? <function>setcookie</function> ???</title>

     <programlisting role="php">

<![CDATA[

<?php

if (isset($_COOKIE['count'])) {

    $count = $_COOKIE['count'] + 1;

} else {

    $count = 1;

}

setcookie('count', $count, time()+3600);

setcookie("Cart[$count]", $item, time()+3600);

?>

]]>

     </programlisting>

    </example>



   </sect2>



   <sect2 xml:id="language.variables.external.dot-in-names">

    <title>??????</title>



    <para>

     ???PHP ?????????????????????????????

     PHP ??????????????????

     <programlisting role="php">

<![CDATA[

<?php

$varname.ext;  /* ????? */

?>

]]>

     </programlisting>

     ?????????????

     <varname>$varname</varname>

     ?????????????????????????????????????????????????????????'ext'?????????????

    </para>



    <para>

     ????????? PHP

     ??????????????????

    </para>



   </sect2>



   <sect2 xml:id="language.variables.determining-type-of">

    <title>??????</title>



    <para>

     ?? PHP ??????????????????????????????????????????????PHP

     ???????????????????<function>gettype</function>?<function>is_array</function>?<function>is_float</function>?<function>is_int</function>?<function>is_object</function> ?

     <function>is_string</function>???<link

     linkend="language.types">??</link>???

    </para>

   </sect2>



  </sect1>



 </chapter>



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