cvs: phpdoc /he/language variables.xml
| From: | shlomi loubaton | Date: | Wed, 06 Feb 2002 02:46:20 +0000 |
| Subject: | cvs: phpdoc /he/language variables.xml | ||
| Groups: | php.doc | ||
| Request: | Send a blank email to phpdoc+get-969341936@lists.php.net to get a copy of this message | ||
shlomi Tue Feb 5 21:46:20 2002 EDT
Added files:
/phpdoc/he/language variables.xml
Log:
half translated...
Index: phpdoc/he/language/variables.xml +++ phpdoc/he/language/variables.xml <?xml version="1.0" encoding="iso-8859-1"?> <!-- EN-Revision: 1.33 Maintainer: shlomi Status: working --> <chapter id="language.variables"> <title>Variables</title> <sect1 id="language.variables.basics"> <title>Basics</title> <simpara> îùúðéí á-PHP îéåöâéí òì-éãé ùí òí ñéîï äãåìø áúçéìúå. ÷ééîú äáçðä áéï àåúéåú úçéìéåú ìàåúéåú øâéìåú áùîåú äîùúðéí (case-sensitive). </simpara> <para> çå÷é ëì äúåéåú á-PHP ú÷ôéí âí ìâáé ùîåú îùúðéí. ùí îùúðä ú÷éï éúçéì òí àåú àå úå ä÷å-äúçúåï åàçøéå éúëï øöó ùì àåúéåú îñôøéí àå ÷å-úçúåï. ðéúï ìúàø àú çå÷éåú ùí äîùúðä áòæøú áéèåé øâåìøé ëæä: '[a-zA-Z_\x7f-\xff][a-zA-Z0-9_\x7f-\xff]*' </para> <note> <simpara> äëååðä ôä äéà ìúåéí a-z,A-Z åúåé ä-ASCII îúå îñôø 127 òã úå 255 (0x7f-0xff) . </simpara> </note> <para> <informalexample> <programlisting role="php"> <![CDATA[ $var = "Bob"; $Var = "Joe"; echo "$var, $Var"; // outputs "Bob, Joe" $4site = 'not yet'; // invalid; starts with a number $_4site = 'not yet'; // valid; starts with an underscore $täyte = 'mansikka'; // valid; 'ä' is ASCII 228. ]]> </programlisting> </informalexample> </para> <para> á-PHP 3 úîéã îöéáéí òøëéí ìîùúðä. ëìåîø, ëàùø ðöéá áéèåé ìîùúðä, îåòú÷ òøëå ùì ëì äáéèåé ìúåê äîùúðä. ëàùø ðöéá àú òøëå ùì îùúðä îñåééí ìîùúðä àçø, ùéðåé òøëå ùì àçã äîùúðéí ìà éùôéò òì äîùúðä äùðé. ìîéãò ðåñó áðåùà éù ìòééï áôø÷ ä<link linkend="language.expressions">áéèåééí</link>. </para> <para> äçì îâøñä 4 ùì PHP ðéúï ìäùúîù áãøê ðåñôú ìäöáú îùúðéí: <emphasis>äöáä áòæøú îëååï(reference)</emphasis>. ëìåîø ðéúï ìéöåø îùúðä çãù ùîöáéò (áîéìéí àçøåú "îëååï ì" àå "ðäôê ìëéðåé ùì" îùúðä) ìîùúðä äî÷åøé. ùéðåé áòøëå ùì äîùúðä äçãù éúáöò âí òì äîùúðä äî÷åøé åìäôê. ìà îúáöòú ëàï äòú÷ä åìëï ääöáä úúáöòä áöåøä îäéøä éåúø àê ìà ðéúï ìäáçéï áäôøù æîðéí àìà àí îãåáø áìåìàåú àøåëåú àå äöáä ùì îòøëéí åàåáéé÷èéí âãåìéí áîéåçã. </para> <para> ëãé ìáöò äöáä áòæøú îëååï éù ìäåñéó àîôøñðã (&) áúçéìú ùí äîùúðä ùîëååðéí àìéå (îùúðä äî÷åø). ìãåâîä, äñ÷øéôè äáà éãôéñ ôòîééí àú äîçøåæú 'My name is Bob' : <informalexample> <programlisting role="php"> <![CDATA[ <?php $foo = 'Bob'; // Assign the value 'Bob' to $foo $bar = &$foo; // Reference $foo via $bar. $bar = "My name is $bar"; // Alter $bar... echo $foo; // $foo is altered too. echo $bar; ?> ]]> </programlisting> </informalexample> </para> <para> çùåá ìöééï ëé ø÷ îùúðä áòì ùí éëåì ì÷áì äöáä áòæøú îëååï. <informalexample> <programlisting role="php"> <![CDATA[ <?php $foo = 25; $bar = &$foo; // ô÷åãä ú÷éðä $bar = &(24 * 7); // ô÷åãä ìà ú÷éðä, äëååðä ìáéèåé ììà ùí function test() { return 25; } $bar = &test(); // ìà ú÷éï ?> ]]> </programlisting> </informalexample> </para> </sect1> <sect1 id="language.variables.predefined"> <title>îùúðéí îåâãøéí îøàù</title> <simpara> PHP îñô÷ú îñôø âãåì ùì îùúðéí "îåâãøéí îøàù" ìëì ñ÷øéôè ùäéà îøéöä. çì÷ îîùúðéí àìä ìà îúåòãéí áàåôï îìà ëé äí úìåééí áùøú, áâøñúå, áäâãøåúéå åáâåøîéí ðåñôéí. çì÷ îîùúðéí àìä ìà éäéå æîðéí ëàùø ñ÷øéôè PHP îåøõ îùåøú äô÷åãä. </simpara> <simpara> ìîøåú âåøîéí àìä, ìôðéëí øùéîä ùì îùúðéí îåâãøéí îøàù äæîéðéí áäú÷ðä øâéìä ùì PHP áâøñä 3 ëîåãåì ùì ùøú <ulink url="&url.apache;">Apache</ulink> 1.3.6. </simpara> <simpara> ì÷áìú øùéîä îìàä ùì ëì äîåâãøéí îøàù äæîéðéí ìùéîåù (åäîåï îéãò ùéîåùé ðåñó), éù ìòééï åìäùúîù áôåð÷öéä <function>phpinfo</function>. </simpara> <note> <simpara> øùéîä æå àéðä îìàä åàéðä îúééîøú ìäéåú ëæå. æå øùéîä ùîèøúä ìñô÷ ÷åéí-îðçéí ìñåâ äîùúðéí äîåâãøéí îøàù ùðéúï ìöôåú ëé éäéå æîéðéí áòú äøöú ñ÷øéôè. </simpara> </note> <sect2 id="language.variables.predefined.apache"> <title>îùúðéí ùì ùøú Apache</title> <simpara> îùúðéí àìå îåâãøéí òì-éãé ùøú <ulink url="&url.apache;">Apache</ulink>. áòú äôòìú ùøú îñåâ æä éúëï ùçì÷ îîùúðéí àìå ìà îåâãøéí åéúëï ùéåâãøå îùúðéí àçøéí ùàéðí øùåîéí ôä. øåá äîùúðéí îôåøèéí á<ulink url="&url.cgispec;">îôøè CGI 1.1</ulink> åñáéø ùéäéå æîéðéí ìùéîåù. </simpara> <simpara> éù ìöééï ëé ëì äîùúðéí äàìä ìà éäéå îåâãøéí áäøöú ñ÷øéôè PHP îùåøú äô÷åãä. </simpara> <para> <variablelist> <varlistentry> <term>$GATEWAY_INTERFACE</term> <listitem> <simpara> âøñú ä-CGI ùäùøú úåîê áä. (áãøê-ëìì 'CGI/1.1' ). </simpara> </listitem> </varlistentry> <varlistentry> <term>$SERVER_NAME</term> <listitem> <simpara> ùí ä-host ùúçúéå øõ äñ÷øéôè äðåëçé. àí äñ÷øéôè øõ úçú host åéøèåàìé, îùúðä æä éëéì àú ùí ä-host äåéøèåàìé. </simpara> </listitem> </varlistentry> <varlistentry> <term>$SERVER_SOFTWARE</term> <listitem> <simpara> îçøåæú äæéäåé ùì äùøú ùîåòáøú áëåúøéí (headers) áòú îùåá ìôðéåú (requests). </simpara> </listitem> </varlistentry> <varlistentry> <term>$SERVER_PROTOCOL</term> <listitem> <simpara> ùí åâøñú äôøåèå÷åì ì÷áìú äôðéåú. (áãøê-ëìì 'HTTP/1.0' ) </simpara> </listitem> </varlistentry> <varlistentry> <term>$REQUEST_METHOD</term> <listitem> <simpara> ñåâ äùéèä ùáòæøúä äúáöòä ôðééä ìùøú. éëéì îçøåæú ëâåï: 'GET','HEAD', 'POST', 'PUT'. </simpara> </listitem> </varlistentry> <varlistentry> <term>$QUERY_STRING</term> <listitem> <simpara> îçøåæú äôðééä (query string) ùãøëä äúáöòä âéùä ìòîåã. </simpara> </listitem> </varlistentry> <varlistentry> <term>$DOCUMENT_ROOT</term> <listitem> <simpara> äñôøéä äøàùéú ùúçúéä øõ äñ÷øéôè äðåëçé ìôé äâãøåú äùøú. </simpara> </listitem> </varlistentry> <varlistentry> <term>$HTTP_ACCEPT</term> <listitem> <simpara> úëåìú ëåúø ä-<literal>Accept:</literal> áôðééä äðåëçéú, àí ÷ééí ëåúø ëæä. </simpara> </listitem> </varlistentry> <varlistentry> <term>$HTTP_ACCEPT_CHARSET</term> <listitem> <simpara> úëåìú ëåúø ä-<literal>Accept-Charset:</literal> áôðééä äðåëçéú, àí ÷ééí ëåúø ëæä. ìãåâîä: 'iso-8859-1,*,utf-8'. </simpara> </listitem> </varlistentry> <varlistentry> <term>$HTTP_ACCEPT_ENCODING</term> <listitem> <simpara> úëåìú ëåúø ä-<literal>Accept-Encoding:</literal> áôðééä äðåëçéú, àí ÷ééí ëåúø ëæä. ìãåâîä: 'gzip'. </simpara> </listitem> </varlistentry> <varlistentry> <term>$HTTP_ACCEPT_LANGUAGE</term> <listitem> <simpara> úëåìú ëåúø ä-<literal>Accept-Language:</literal> áôðééä äðåëçéú, àí ÷ééí ëåúø ëæä. ìãåâîä: 'en'. </simpara> </listitem> </varlistentry> <varlistentry> <term>$HTTP_CONNECTION</term> <listitem> <simpara> úëåìú ëåúø ä-<literal>Connection:</literal> áôðééä äðåëçéú, àí ÷ééí ëåúø ëæä. ìãåâîä: 'Keep-Alive'. </simpara> </listitem> </varlistentry> <varlistentry> <term>$HTTP_HOST</term> <listitem> <simpara> úëåìú ëåúø ä-<literal>Host:</literal> áôðééä äðåëçéú, àí ÷ééí ëåúø ëæä. </simpara> </listitem> </varlistentry> <varlistentry> <term>$HTTP_REFERER</term> <listitem> <simpara> ëúåáúå ùì äòîåã (àí ÷ééí) ùäôðä àú äãôãôï ìòîåã äðåëçé. îùúðä æä ð÷áò òì-éãé ãôãôï äîùúîù. ìà ëì äãôãôðéí úåîëéí áàôùøåú æå. </simpara> </listitem> </varlistentry> <varlistentry> <term>$HTTP_USER_AGENT</term> <listitem> <simpara> úëåìú ëåúø ä-<literal>User_Agent:</literal> áôðééä äðåëçéú, àí ÷ééí ëåúø ëæä. îëéì îçøåæú äîöäéøä ñåâ äãôãôï äîùîù ìöôééä áòîåã äðåëçé. ëâåï:<computeroutput>Mozilla/4.5 [en] (X11; U; Linux 2.2.9 i586)</computeroutput>. ðéúï ìäùúîù áòøê æä åáòøê äôåð÷öéä <function>get_browser</function> ëãé ìàôùø áðééä ùì äòîåã úåê äúçùáåú áéëåìúå åñåâå ùì äãôãôï. </simpara> </listitem> </varlistentry> <varlistentry> <term>$REMOTE_ADDR</term> <listitem> <simpara> ëúåáú ä- IP ùîîðä äîùúîù öåôä áòîåã äðåëçé. </simpara> </listitem> </varlistentry> <varlistentry> <term>$REMOTE_PORT</term> <listitem> <simpara> ä-port ùãøëå îú÷ùø îçùáå ùì äîùúîù òí äùøú. </simpara> </listitem> </varlistentry> <varlistentry> <term>$SCRIPT_FILENAME</term> <listitem> <simpara> ùí äðúéá (pathname) äàáñåìåèé ùáå îåøõ äñ÷øéôè äðåëçé. </simpara> </listitem> </varlistentry> <varlistentry> <term>$SERVER_ADMIN</term> <listitem> <simpara> äòøê äîåòáø ìàåôöééú ä-SERVER_ADMIN ùì ùøú Apache á÷åáõ ääâãøåú ùì äùøú. àí äñ÷øéôè øõ úçú host åéøèåàìé, îùúðä æä éåâãø ì-host åéøèåàìé æä. </simpara> </listitem> </varlistentry> <varlistentry> <term>$SERVER_PORT</term> <listitem> <simpara> îñôø ä-port äîùîù ìú÷ùåøú ùì äùøú. äøéøú äîçãì äéà 80. ëàùø îùúîùéí á-SSL ìîùì, îñôø æä éùúðä ìôé ä-port ùäåâãø ë-secure HTTP port . </simpara> </listitem> </varlistentry> <varlistentry> <term>$SERVER_SIGNATURE</term> <listitem> <simpara> String containing the server version and virtual host name which are added to server-generated pages, if enabled. </simpara> </listitem> </varlistentry> <varlistentry> <term>$PATH_TRANSLATED</term> <listitem> <simpara> ðúéá îáåññ ìôé îòøëú ä÷áöéí ùì äñ÷øéôè äðåëçé (æä ìà document root ùì äñ÷øéôè) ìàçø ùáåöò îéôåé åéøèåàìé ìøéàìé. </simpara> </listitem> </varlistentry> <varlistentry> <term>$SCRIPT_NAME</term> <listitem> <simpara> îëéì àú ðúéá äñ÷øéôè äðåëçé. ùéîåùé ìòîåãéí ùîöáéòéí ìòöîí. </simpara> </listitem> </varlistentry> <varlistentry> <term>$REQUEST_URI</term> <listitem> <simpara> ëúåáú ä-URI äîùîùú ìâéùä ìòîåã äðåëçé. ìãåâîä: /index.html'. </simpara> </listitem> </varlistentry> </variablelist> </para> </sect2> <sect2 id="language.variables.predefined.environment"> <title>îùúðé ñáéáä</title> <simpara> These variables are imported into PHP's global namespace from the environment under which the PHP parser is running. Many are provided by the shell under which PHP is running and different systems are likely running different kinds of shells, a definitive list is impossible. Please see your shell's documentation for a list of defined environment variables. </simpara> <simpara> Other environment variables include the CGI variables, placed there regardless of whether PHP is running as a server module or CGI processor. </simpara> </sect2> <sect2 id="language.variables.predefined.php"> <title>PHP variables</title> <simpara> These variables are created by PHP itself. The <varname>$HTTP_*_VARS</varname> variables are available only if the <link linkend="ini.track-vars">track_vars</link> configuration is turned on. When enabled, the variables are always set, even if they are empty arrays. This prevents a malicious user from spoofing these variables. </simpara> <note> <para> As of PHP 4.0.3, <link linkend="ini.track-vars">track_vars</link> is always turned on, regardless of the configuration file setting. </para> </note> <note> <para> The new "Superglobals" were added in PHP version 4.1.0. See the <ulink url="&url.php.release4.1.0;">4.1.0 Release Announcement</ulink> for more details. These are the <varname>$_GET</varname>, <varname>$_POST</varname>, <varname>$_ENV</varname>, <varname>$_SERVER</varname>, <varname>$_COOKIE</varname>, <varname>$_REQUEST</varname> <varname>$_FILES</varname>, and <varname>$_SESSION</varname> arrays, and they are informally known as <emphasis>Superglobals</emphasis> since they are always available without regard to scope. These deprecate the older respective <varname>$HTTP_*_VARS</varname> arrays. </para> </note> <para> If the <link linkend="ini.register-globals">register_globals</link> directive is set, then these variables will also be made available in the global scope of the script; i.e., separate from the <varname>$HTTP_*_VARS</varname> and <varname>$_*</varname> arrays. For related information, see the security chapter titled <link linkend="security.registerglobals">Using Register Globals</link>. </para> <para> <variablelist> <varlistentry> <term>$argv</term> <listitem> <simpara> Array of arguments passed to the script. When the script is run on the command line, this gives C-style access to the command line parameters. When called via the GET method, this will contain the query string. </simpara> </listitem> </varlistentry> <varlistentry> <term>$argc</term> <listitem> <simpara> Contains the number of command line parameters passed to the script (if run on the command line). </simpara> </listitem> </varlistentry> <varlistentry> <term>$PHP_SELF</term> <listitem> <simpara> The filename of the currently executing script, relative to the document root. If PHP is running as a command-line processor, this variable is not available. </simpara> </listitem> </varlistentry> <varlistentry> <term>$HTTP_COOKIE_VARS</term> <listitem> <simpara> An associative array of variables passed to the current script via HTTP cookies. </simpara> </listitem> </varlistentry> <varlistentry> <term>$_COOKIE</term> <listitem> <simpara> An associative array of variables passed to the current script via HTTP cookies. Automatically global in any scope. Introduced in PHP 4.1.0. </simpara> </listitem> </varlistentry> <varlistentry> <term>$HTTP_GET_VARS</term> <listitem> <simpara> An associative array of variables passed to the current script via the HTTP GET method. </simpara> </listitem> </varlistentry> <varlistentry> <term>$_GET</term> <listitem> <simpara> An associative array of variables passed to the current script via the HTTP GET method. Automatically global in any scope. Introduced in PHP 4.1.0. </simpara> </listitem> </varlistentry> <varlistentry> <term>$HTTP_POST_VARS</term> <listitem> <simpara> An associative array of variables passed to the current script via the HTTP POST method. </simpara> </listitem> </varlistentry> <varlistentry> <term>$_POST</term> <listitem> <simpara> An associative array of variables passed to the current script via the HTTP POST method. Automatically global in any scope. Introduced in PHP 4.1.0. </simpara> </listitem> </varlistentry> <varlistentry> <term>$HTTP_POST_FILES</term> <listitem> <simpara> An associative array of variables containing information about files uploaded via the HTTP POST method. See <link linkend="features.file-upload.post-method">POST method uploads</link> for information on the contents of <varname>$HTTP_POST_FILES</varname>. Introduced in 4.0.0. </simpara> </listitem> </varlistentry> <varlistentry> <term>$_FILES</term> <listitem> <simpara> An associative array of variables containing information about files uploaded via the HTTP POST method. See <link linkend="features.file-upload.post-method">POST method uploads</link> for information on the contents of <varname>$_FILES</varname>. Automatically global in any scope. Introduced in PHP 4.1.0. </simpara> </listitem> </varlistentry> <varlistentry> <term>$HTTP_ENV_VARS</term> <listitem> <simpara> An associative array of variables passed to the current script via the parent environment. </simpara> </listitem> </varlistentry> <varlistentry> <term>$_ENV</term> <listitem> <simpara> An associative array of variables passed to the current script via the parent environment. Automagically global in any scope. Introduced in PHP 4.1.0. </simpara> </listitem> </varlistentry> <varlistentry> <term>$HTTP_SERVER_VARS</term> <listitem> <simpara> An associative array of variables passed to the current script from the HTTP server. These variables are analogous to the Apache variables described above. </simpara> </listitem> </varlistentry> <varlistentry> <term>$_SERVER</term> <listitem> <simpara> An associative array of variables passed to the current script from the HTTP server. These variables are analogous to the Apache variables described above. Automatically global in any scope. Introduced in PHP 4.1.0. </simpara> </listitem> </varlistentry> <varlistentry> <term>$HTTP_SESSION_VARS</term> <listitem> <simpara> An associative array of session variables passed to the current script. </simpara> </listitem> </varlistentry> <varlistentry> <term>$_SESSION</term> <listitem> <simpara> An associative array of session variables passed to the current script. Automatically global in any scope. Creating new entries in the $_SESSION array will automatically register them as session variables, as if you called <function>session_register</function>. Introduced in PHP 4.1.0. </simpara> </listitem> </varlistentry> <varlistentry> <term>$_REQUEST</term> <listitem> <simpara> An associative array merged from the GET, POST, and Cookie variables. In other words - all the information that is coming from the user, and that from a security point of view, cannot be trusted. Automatically global in any scope. Introduced in PHP 4.1.0. </simpara> </listitem> </varlistentry> </variablelist> </para> </sect2> </sect1> <sect1 id="language.variables.scope"> <title>Variable scope</title> <simpara> The scope of a variable is the context within which it is defined. For the most part all PHP variables only have a single scope. This single scope spans included and required files as well. For example: </simpara> <informalexample> <programlisting role="php"> <![CDATA[ $a = 1; include "b.inc"; ]]> </programlisting> </informalexample> <simpara> Here the <varname>$a</varname> variable will be available within the included <filename>b.inc</filename> script. However, within user-defined functions a local function scope is introduced. Any variable used inside a function is by default limited to the local function scope. For example: </simpara> <informalexample> <programlisting role="php"> <![CDATA[ $a = 1; /* global scope */ function Test() { echo $a; /* reference to local scope variable */ } Test(); ]]> </programlisting> </informalexample> <simpara> This script will not produce any output because the echo statement refers to a local version of the <varname>$a</varname> variable, and it has not been assigned a value within this scope. You may notice that this is a little bit different from the C language in that global variables in C are automatically available to functions unless specifically overridden by a local definition. This can cause some problems in that people may inadvertently change a global variable. In PHP global variables must be declared global inside a function if they are going to be used in that function. An example: </simpara> <informalexample> <programlisting role="php"> <![CDATA[ $a = 1; $b = 2; function Sum() { global $a, $b; $b = $a + $b; } Sum(); echo $b; ]]> </programlisting> </informalexample> <simpara> The above script will output "3". By declaring <varname>$a</varname> and <varname>$b</varname> global within the function, all references to either variable will refer to the global version. There is no limit to the number of global variables that can be manipulated by a function. </simpara> <simpara> A second way to access variables from the global scope is to use the special PHP-defined <varname>$GLOBALS</varname> array. The previous example can be rewritten as: </simpara> <informalexample> <programlisting role="php"> <![CDATA[ $a = 1; $b = 2; function Sum() { $GLOBALS["b"] = $GLOBALS["a"] + $GLOBALS["b"]; } Sum(); echo $b; ]]> </programlisting> </informalexample> <simpara> The <varname>$GLOBALS</varname> array is an associative array with the name of the global variable being the key and the contents of that variable being the value of the array element. </simpara> <simpara> Another important feature of variable scoping is the <emphasis>static</emphasis> variable. A static variable exists only in a local function scope, but it does not lose its value when program execution leaves this scope. Consider the following example: </simpara> <informalexample> <programlisting role="php"> <![CDATA[ function Test () { $a = 0; echo $a; $a++; } ]]> </programlisting> </informalexample> <simpara> This function is quite useless since every time it is called it sets <varname>$a</varname> to <literal>0</literal> and prints "0". The <varname>$a</varname>++ which increments the variable serves no purpose since as soon as the function exits the <varname>$a</varname> variable disappears. To make a useful counting function which will not lose track of the current count, the <varname>$a</varname> variable is declared static: </simpara> <informalexample> <programlisting role="php"> <![CDATA[ function Test() { static $a = 0; echo $a; $a++; } ]]> </programlisting> </informalexample> <simpara> Now, every time the Test() function is called it will print the value of <varname>$a</varname> and increment it. </simpara> <simpara> Static variables also provide one way to deal with recursive functions. A recursive function is one which calls itself. Care must be taken when writing a recursive function because it is possible to make it recurse indefinitely. You must make sure you have an adequate way of terminating the recursion. The following simple function recursively counts to 10, using the static variable <varname>$count</varname> to know when to stop: </simpara> <informalexample> <programlisting role="php"> <![CDATA[ function Test() { static $count = 0; $count++; echo $count; if ($count < 10) { Test (); } $count--; } ]]> </programlisting> </informalexample> </sect1> <sect1 id="language.variables.variable"> <title>Variable variables</title> <simpara> Sometimes it is convenient to be able to have variable variable names. That is, a variable name which can be set and used dynamically. A normal variable is set with a statement such as: </simpara> <informalexample> <programlisting role="php"> <![CDATA[ $a = "hello"; ]]> </programlisting> </informalexample> <simpara> A variable variable takes the value of a variable and treats that as the name of a variable. In the above example, <emphasis>hello</emphasis>, can be used as the name of a variable by using two dollar signs. i.e. </simpara> <informalexample> <programlisting role="php"> <![CDATA[ $$a = "world"; ]]> </programlisting> </informalexample> <simpara> At this point two variables have been defined and stored in the PHP symbol tree: <varname>$a</varname> with contents "hello" and <varname>$hello</varname> with contents "world". Therefore, this statement: </simpara> <informalexample> <programlisting role="php"> <![CDATA[ echo "$a ${$a}"; ]]> </programlisting> </informalexample> <simpara> produces the exact same output as: </simpara> <informalexample> <programlisting role="php"> <![CDATA[ echo "$a $hello"; ]]> </programlisting> </informalexample> <simpara> i.e. they both produce: <computeroutput>hello world</computeroutput>. </simpara> <simpara> In order to use variable variables with arrays, you have to resolve an ambiguity problem. That is, if you write <varname>$$a[1]</varname> then the parser needs to know if you meant to use <varname>$a[1]</varname> as a variable, or if you wanted <varname>$$a</varname> as the variable and then the [1] index from that variable. The syntax for resolving this ambiguity is: <varname>${$a[1]}</varname> for the first case and <varname>${$a}[1]</varname> for the second. </simpara> </sect1> <sect1 id="language.variables.external"> <title>Variables from outside PHP</title> <sect2 id="language.variables.external.form"> <title>HTML Forms (GET and POST)</title> <simpara> 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 <link linkend="ini.track-vars">track_vars</link> configuration option is turned on, then these variables will be located in the associative arrays <varname>$HTTP_POST_VARS</varname>, <varname>$HTTP_GET_VARS</varname>, and/or <varname>$HTTP_POST_FILES</varname>, according to the source of the variable in question. </simpara> <para> For more information on these variables, please read <link linkend="language.variables.predefined">Predefined variables</link>. </para> <para> <example> <title>Simple form variable</title> <programlisting role="php"> <![CDATA[ <form action="foo.php" method="post"> Name: <input type="text" name="username"><br> <input type="submit"> </form> ]]> </programlisting> </example> </para> <para> When the above form is submitted, the value from the text input will be available in <varname>$HTTP_POST_VARS['username']</varname>. If the <link linkend="ini.register-globals">register_globals</link> configuration directive is turned on, then the variable will also be available as <varname>$username</varname> in the global scope. </para> <note> <para> The <link linkend="ini.magic-quotes-gpc">magic_quotes_gpc</link> configuration directive affects Get, Post and Cookie values. If turned on, value (It's "PHP!") will automagically become (It\'s \"PHP!\"). Escaping is needed for DB insertion. Also see <function>addslashes</function>, <function>stripslashes</function> and <link linkend="ini.magic-quotes-sybase">magic_quotes_sybase</link>. </para> </note> <simpara> PHP also understands arrays in the context of form variables (see the <link linkend="faq.html">related faq</link>). You may, for example, group related variables together, or use this feature to retrieve values from a multiple select input: </simpara> <para> <example> <title>More complex form variables</title> <programlisting role="php"> <![CDATA[ <form action="array.php" 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 value="guinness">Guinness <option value="stuttgarter">Stuttgarter Schwabenbräu </select> <input type="submit"> </form> ]]> </programlisting> </example> </para> <para> In PHP 3, the array form variable usage is limited to single-dimensional arrays. In PHP 4, no such restriction applies. </para> <sect3 id="language.variables.external.form.submit"> <title>IMAGE SUBMIT variable names</title> <simpara> When submitting a form, it is possible to use an image instead of the standard submit button with a tag like:</simpara> <informalexample> <programlisting role="php"> <![CDATA[ <input type="image" src="image.gif" name="sub"> ]]> </programlisting> </informalexample> <simpara> 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. </simpara> </sect3> </sect2> <sect2 id="language.variables.external.cookies"> <title>HTTP Cookies</title> <simpara> PHP transparently supports HTTP cookies as defined by <ulink url="&spec.cookies;">Netscape's Spec</ulink>. Cookies are a mechanism for storing data in the remote browser and thus tracking or identifying return users. You can set cookies using the <function>setcookie</function> 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 <function>header</function> function. Any cookies sent to you from the client will automatically be turned into a PHP variable just like GET and POST method data.</simpara> <simpara> If you wish to assign multiple values to a single cookie, just add <emphasis>[]</emphasis> to the cookie name. For example: </simpara> <informalexample> <programlisting role="php"> <![CDATA[ setcookie("MyCookie[]", "Testing", time()+3600); ]]> </programlisting> </informalexample> <simpara> 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. </simpara> <example> <title>SetCookie Example</title> <programlisting role="php"> <![CDATA[ $Count++; setcookie("Count", $Count, time()+3600); setcookie("Cart[$Count]", $item, time()+3600); ]]> </programlisting> </example> </sect2> <sect2 id="language.variables.external.environment"> <title>Environment variables</title> <para> PHP automatically makes environment variables available as normal PHP variables. <informalexample> <programlisting role="php"> <![CDATA[ echo $HOME; /* Shows the HOME environment variable, if set. */ ]]> </programlisting> </informalexample> </para> <para> 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 <function>getenv</function> function can be used for this. You can also set an environment variable with the <function>putenv</function> function. </para> </sect2> <sect2 id="language.variables.external.dot-in-names"> <title>Dots in incoming variable names</title> <para> 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: <programlisting role="php"> <![CDATA[ $varname.ext; /* invalid variable name */ ]]> </programlisting> Now, what the parser sees is a variable named <varname>$varname</varname>, 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. </para> <para> For this reason, it is important to note that PHP will automatically replace any dots in incoming variable names with underscores. </para> </sect2> <sect2 id="language.variables.determining-type-of"> <title>Determining variable types</title> <para> 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 <function>gettype</function>, <function>is_long</function>, <function>is_double</function>, <function>is_string</function>, <function>is_array</function>, and <function>is_object</function>. </para> </sect2> </sect1> </chapter> <!-- Keep this comment at the end of the file Local variables: mode: sgml sgml-omittag:t sgml-shorttag:t sgml-minimize-attributes:nil sgml-always-quote-attributes:t sgml-indent-step:1 sgml-indent-data:t indent-tabs-mode:nil sgml-parent-document:nil sgml-default-dtd-file:"../../manual.ced" sgml-exposed-tags:nil sgml-local-catalogs:nil sgml-local-ecat-files:nil End: vim600: syn=xml fen fdm=syntax fdl=2 si vim: et tw=78 syn=sgml vi: ts=1 sw=1 -->
Index: phpdoc/he/language/variables.xml +++ phpdoc/he/language/variables.xml <?xml version="1.0" encoding="iso-8859-1"?> <!-- EN-Revision: 1.33 Maintainer: shlomi Status: working --> <chapter id="language.variables"> <title>Variables</title> <sect1 id="language.variables.basics"> <title>Basics</title> <simpara> îùúðéí á-PHP îéåöâéí òì-éãé ùí òí ñéîï äãåìø áúçéìúå. ÷ééîú äáçðä áéï àåúéåú úçéìéåú ìàåúéåú øâéìåú áùîåú äîùúðéí (case-sensitive). </simpara> <para> çå÷é ëì äúåéåú á-PHP ú÷ôéí âí ìâáé ùîåú îùúðéí. ùí îùúðä ú÷éï éúçéì òí àåú àå úå ä÷å-äúçúåï åàçøéå éúëï øöó ùì àåúéåú îñôøéí àå ÷å-úçúåï. ðéúï ìúàø àú çå÷éåú ùí äîùúðä áòæøú áéèåé øâåìøé ëæä: '[a-zA-Z_\x7f-\xff][a-zA-Z0-9_\x7f-\xff]*' </para> <note> <simpara> äëååðä ôä äéà ìúåéí a-z,A-Z åúåé ä-ASCII îúå îñôø 127 òã úå 255 (0x7f-0xff) . </simpara> </note> <para> <informalexample> <programlisting role="php"> <![CDATA[ $var = "Bob"; $Var = "Joe"; echo "$var, $Var"; // outputs "Bob, Joe" $4site = 'not yet'; // invalid; starts with a number $_4site = 'not yet'; // valid; starts with an underscore $täyte = 'mansikka'; // valid; 'ä' is ASCII 228. ]]> </programlisting> </informalexample> </para> <para> á-PHP 3 úîéã îöéáéí òøëéí ìîùúðä. ëìåîø, ëàùø ðöéá áéèåé ìîùúðä, îåòú÷ òøëå ùì ëì äáéèåé ìúåê äîùúðä. ëàùø ðöéá àú òøëå ùì îùúðä îñåééí ìîùúðä àçø, ùéðåé òøëå ùì àçã äîùúðéí ìà éùôéò òì äîùúðä äùðé. ìîéãò ðåñó áðåùà éù ìòééï áôø÷ ä<link linkend="language.expressions">áéèåééí</link>. </para> <para> äçì îâøñä 4 ùì PHP ðéúï ìäùúîù áãøê ðåñôú ìäöáú îùúðéí: <emphasis>äöáä áòæøú îëååï(reference)</emphasis>. ëìåîø ðéúï ìéöåø îùúðä çãù ùîöáéò (áîéìéí àçøåú "îëååï ì" àå "ðäôê ìëéðåé ùì" îùúðä) ìîùúðä äî÷åøé. ùéðåé áòøëå ùì äîùúðä äçãù éúáöò âí òì äîùúðä äî÷åøé åìäôê. ìà îúáöòú ëàï äòú÷ä åìëï ääöáä úúáöòä áöåøä îäéøä éåúø àê ìà ðéúï ìäáçéï áäôøù æîðéí àìà àí îãåáø áìåìàåú àøåëåú àå äöáä ùì îòøëéí åàåáéé÷èéí âãåìéí áîéåçã. </para> <para> ëãé ìáöò äöáä áòæøú îëååï éù ìäåñéó àîôøñðã (&) áúçéìú ùí äîùúðä ùîëååðéí àìéå (îùúðä äî÷åø). ìãåâîä, äñ÷øéôè äáà éãôéñ ôòîééí àú äîçøåæú 'My name is Bob' : <informalexample> <programlisting role="php"> <![CDATA[ <?php $foo = 'Bob'; // Assign the value 'Bob' to $foo $bar = &$foo; // Reference $foo via $bar. $bar = "My name is $bar"; // Alter $bar... echo $foo; // $foo is altered too. echo $bar; ?> ]]> </programlisting> </informalexample> </para> <para> çùåá ìöééï ëé ø÷ îùúðä áòì ùí éëåì ì÷áì äöáä áòæøú îëååï. <informalexample> <programlisting role="php"> <![CDATA[ <?php $foo = 25; $bar = &$foo; // ô÷åãä ú÷éðä $bar = &(24 * 7); // ô÷åãä ìà ú÷éðä, äëååðä ìáéèåé ììà ùí function test() { return 25; } $bar = &test(); // ìà ú÷éï ?> ]]> </programlisting> </informalexample> </para> </sect1> <sect1 id="language.variables.predefined"> <title>îùúðéí îåâãøéí îøàù</title> <simpara> PHP îñô÷ú îñôø âãåì ùì îùúðéí "îåâãøéí îøàù" ìëì ñ÷øéôè ùäéà îøéöä. çì÷ îîùúðéí àìä ìà îúåòãéí áàåôï îìà ëé äí úìåééí áùøú, áâøñúå, áäâãøåúéå åáâåøîéí ðåñôéí. çì÷ îîùúðéí àìä ìà éäéå æîðéí ëàùø ñ÷øéôè PHP îåøõ îùåøú äô÷åãä. </simpara> <simpara> ìîøåú âåøîéí àìä, ìôðéëí øùéîä ùì îùúðéí îåâãøéí îøàù äæîéðéí áäú÷ðä øâéìä ùì PHP áâøñä 3 ëîåãåì ùì ùøú <ulink url="&url.apache;">Apache</ulink> 1.3.6. </simpara> <simpara> ì÷áìú øùéîä îìàä ùì ëì äîåâãøéí îøàù äæîéðéí ìùéîåù (åäîåï îéãò ùéîåùé ðåñó), éù ìòééï åìäùúîù áôåð÷öéä <function>phpinfo</function>. </simpara> <note> <simpara> øùéîä æå àéðä îìàä åàéðä îúééîøú ìäéåú ëæå. æå øùéîä ùîèøúä ìñô÷ ÷åéí-îðçéí ìñåâ äîùúðéí äîåâãøéí îøàù ùðéúï ìöôåú ëé éäéå æîéðéí áòú äøöú ñ÷øéôè. </simpara> </note> <sect2 id="language.variables.predefined.apache"> <title>îùúðéí ùì ùøú Apache</title> <simpara> îùúðéí àìå îåâãøéí òì-éãé ùøú <ulink url="&url.apache;">Apache</ulink>. áòú äôòìú ùøú îñåâ æä éúëï ùçì÷ îîùúðéí àìå ìà îåâãøéí åéúëï ùéåâãøå îùúðéí àçøéí ùàéðí øùåîéí ôä. øåá äîùúðéí îôåøèéí á<ulink url="&url.cgispec;">îôøè CGI 1.1</ulink> åñáéø ùéäéå æîéðéí ìùéîåù. </simpara> <simpara> éù ìöééï ëé ëì äîùúðéí äàìä ìà éäéå îåâãøéí áäøöú ñ÷øéôè PHP îùåøú äô÷åãä. </simpara> <para> <variablelist> <varlistentry> <term>$GATEWAY_INTERFACE</term> <listitem> <simpara> âøñú ä-CGI ùäùøú úåîê áä. (áãøê-ëìì 'CGI/1.1' ). </simpara> </listitem> </varlistentry> <varlistentry> <term>$SERVER_NAME</term> <listitem> <simpara> ùí ä-host ùúçúéå øõ äñ÷øéôè äðåëçé. àí äñ÷øéôè øõ úçú host åéøèåàìé, îùúðä æä éëéì àú ùí ä-host äåéøèåàìé. </simpara> </listitem> </varlistentry> <varlistentry> <term>$SERVER_SOFTWARE</term> <listitem> <simpara> îçøåæú äæéäåé ùì äùøú ùîåòáøú áëåúøéí (headers) áòú îùåá ìôðéåú (requests). </simpara> </listitem> </varlistentry> <varlistentry> <term>$SERVER_PROTOCOL</term> <listitem> <simpara> ùí åâøñú äôøåèå÷åì ì÷áìú äôðéåú. (áãøê-ëìì 'HTTP/1.0' ) </simpara> </listitem> </varlistentry> <varlistentry> <term>$REQUEST_METHOD</term> <listitem> <simpara> ñåâ äùéèä ùáòæøúä äúáöòä ôðééä ìùøú. éëéì îçøåæú ëâåï: 'GET','HEAD', 'POST', 'PUT'. </simpara> </listitem> </varlistentry> <varlistentry> <term>$QUERY_STRING</term> <listitem> <simpara> îçøåæú äôðééä (query string) ùãøëä äúáöòä âéùä ìòîåã. </simpara> </listitem> </varlistentry> <varlistentry> <term>$DOCUMENT_ROOT</term> <listitem> <simpara> äñôøéä äøàùéú ùúçúéä øõ äñ÷øéôè äðåëçé ìôé äâãøåú äùøú. </simpara> </listitem> </varlistentry> <varlistentry> <term>$HTTP_ACCEPT</term> <listitem> <simpara> úëåìú ëåúø ä-<literal>Accept:</literal> áôðééä äðåëçéú, àí ÷ééí ëåúø ëæä. </simpara> </listitem> </varlistentry> <varlistentry> <term>$HTTP_ACCEPT_CHARSET</term> <listitem> <simpara> úëåìú ëåúø ä-<literal>Accept-Charset:</literal> áôðééä äðåëçéú, àí ÷ééí ëåúø ëæä. ìãåâîä: 'iso-8859-1,*,utf-8'. </simpara> </listitem> </varlistentry> <varlistentry> <term>$HTTP_ACCEPT_ENCODING</term> <listitem> <simpara> úëåìú ëåúø ä-<literal>Accept-Encoding:</literal> áôðééä äðåëçéú, àí ÷ééí ëåúø ëæä. ìãåâîä: 'gzip'. </simpara> </listitem> </varlistentry> <varlistentry> <term>$HTTP_ACCEPT_LANGUAGE</term> <listitem> <simpara> úëåìú ëåúø ä-<literal>Accept-Language:</literal> áôðééä äðåëçéú, àí ÷ééí ëåúø ëæä. ìãåâîä: 'en'. </simpara> </listitem> </varlistentry> <varlistentry> <term>$HTTP_CONNECTION</term> <listitem> <simpara> úëåìú ëåúø ä-<literal>Connection:</literal> áôðééä äðåëçéú, àí ÷ééí ëåúø ëæä. ìãåâîä: 'Keep-Alive'. </simpara> </listitem> </varlistentry> <varlistentry> <term>$HTTP_HOST</term> <listitem> <simpara> úëåìú ëåúø ä-<literal>Host:</literal> áôðééä äðåëçéú, àí ÷ééí ëåúø ëæä. </simpara> </listitem> </varlistentry> <varlistentry> <term>$HTTP_REFERER</term> <listitem> <simpara> ëúåáúå ùì äòîåã (àí ÷ééí) ùäôðä àú äãôãôï ìòîåã äðåëçé. îùúðä æä ð÷áò òì-éãé ãôãôï äîùúîù. ìà ëì äãôãôðéí úåîëéí áàôùøåú æå. </simpara> </listitem> </varlistentry> <varlistentry> <term>$HTTP_USER_AGENT</term> <listitem> <simpara> úëåìú ëåúø ä-<literal>User_Agent:</literal> áôðééä äðåëçéú, àí ÷ééí ëåúø ëæä. îëéì îçøåæú äîöäéøä ñåâ äãôãôï äîùîù ìöôééä áòîåã äðåëçé. ëâåï:<computeroutput>Mozilla/4.5 [en] (X11; U; Linux 2.2.9 i586)</computeroutput>. ðéúï ìäùúîù áòøê æä åáòøê äôåð÷öéä <function>get_browser</function> ëãé ìàôùø áðééä ùì äòîåã úåê äúçùáåú áéëåìúå åñåâå ùì äãôãôï. </simpara> </listitem> </varlistentry> <varlistentry> <term>$REMOTE_ADDR</term> <listitem> <simpara> ëúåáú ä- IP ùîîðä äîùúîù öåôä áòîåã äðåëçé. </simpara> </listitem> </varlistentry> <varlistentry> <term>$REMOTE_PORT</term> <listitem> <simpara> ä-port ùãøëå îú÷ùø îçùáå ùì äîùúîù òí äùøú. </simpara> </listitem> </varlistentry> <varlistentry> <term>$SCRIPT_FILENAME</term> <listitem> <simpara> ùí äðúéá (pathname) äàáñåìåèé ùáå îåøõ äñ÷øéôè äðåëçé. </simpara> </listitem> </varlistentry> <varlistentry> <term>$SERVER_ADMIN</term> <listitem> <simpara> äòøê äîåòáø ìàåôöééú ä-SERVER_ADMIN ùì ùøú Apache á÷åáõ ääâãøåú ùì äùøú. àí äñ÷øéôè øõ úçú host åéøèåàìé, îùúðä æä éåâãø ì-host åéøèåàìé æä. </simpara> </listitem> </varlistentry> <varlistentry> <term>$SERVER_PORT</term> <listitem> <simpara> îñôø ä-port äîùîù ìú÷ùåøú ùì äùøú. äøéøú äîçãì äéà 80. ëàùø îùúîùéí á-SSL ìîùì, îñôø æä éùúðä ìôé ä-port ùäåâãø ë-secure HTTP port . </simpara> </listitem> </varlistentry> <varlistentry> <term>$SERVER_SIGNATURE</term> <listitem> <simpara> String containing the server version and virtual host name which are added to server-generated pages, if enabled. </simpara> </listitem> </varlistentry> <varlistentry> <term>$PATH_TRANSLATED</term> <listitem> <simpara> ðúéá îáåññ ìôé îòøëú ä÷áöéí ùì äñ÷øéôè äðåëçé (æä ìà document root ùì äñ÷øéôè) ìàçø ùáåöò îéôåé åéøèåàìé ìøéàìé. </simpara> </listitem> </varlistentry> <varlistentry> <term>$SCRIPT_NAME</term> <listitem> <simpara> îëéì àú ðúéá äñ÷øéôè äðåëçé. ùéîåùé ìòîåãéí ùîöáéòéí ìòöîí. </simpara> </listitem> </varlistentry> <varlistentry> <term>$REQUEST_URI</term> <listitem> <simpara> ëúåáú ä-URI äîùîùú ìâéùä ìòîåã äðåëçé. ìãåâîä: /index.html'. </simpara> </listitem> </varlistentry> </variablelist> </para> </sect2> <sect2 id="language.variables.predefined.environment"> <title>îùúðé ñáéáä</title> <simpara> These variables are imported into PHP's global namespace from the environment under which the PHP parser is running. Many are provided by the shell under which PHP is running and different systems are likely running different kinds of shells, a definitive list is impossible. Please see your shell's documentation for a list of defined environment variables. </simpara> <simpara> Other environment variables include the CGI variables, placed there regardless of whether PHP is running as a server module or CGI processor. </simpara> </sect2> <sect2 id="language.variables.predefined.php"> <title>PHP variables</title> <simpara> These variables are created by PHP itself. The <varname>$HTTP_*_VARS</varname> variables are available only if the <link linkend="ini.track-vars">track_vars</link> configuration is turned on. When enabled, the variables are always set, even if they are empty arrays. This prevents a malicious user from spoofing these variables. </simpara> <note> <para> As of PHP 4.0.3, <link linkend="ini.track-vars">track_vars</link> is always turned on, regardless of the configuration file setting. </para> </note> <note> <para> The new "Superglobals" were added in PHP version 4.1.0. See the <ulink url="&url.php.release4.1.0;">4.1.0 Release Announcement</ulink> for more details. These are the <varname>$_GET</varname>, <varname>$_POST</varname>, <varname>$_ENV</varname>, <varname>$_SERVER</varname>, <varname>$_COOKIE</varname>, <varname>$_REQUEST</varname> <varname>$_FILES</varname>, and <varname>$_SESSION</varname> arrays, and they are informally known as <emphasis>Superglobals</emphasis> since they are always available without regard to scope. These deprecate the older respective <varname>$HTTP_*_VARS</varname> arrays. </para> </note> <para> If the <link linkend="ini.register-globals">register_globals</link> directive is set, then these variables will also be made available in the global scope of the script; i.e., separate from the <varname>$HTTP_*_VARS</varname> and <varname>$_*</varname> arrays. For related information, see the security chapter titled <link linkend="security.registerglobals">Using Register Globals</link>. </para> <para> <variablelist> <varlistentry> <term>$argv</term> <listitem> <simpara> Array of arguments passed to the script. When the script is run on the command line, this gives C-style access to the command line parameters. When called via the GET method, this will contain the query string. </simpara> </listitem> </varlistentry> <varlistentry> <term>$argc</term> <listitem> <simpara> Contains the number of command line parameters passed to the script (if run on the command line). </simpara> </listitem> </varlistentry> <varlistentry> <term>$PHP_SELF</term> <listitem> <simpara> The filename of the currently executing script, relative to the document root. If PHP is running as a command-line processor, this variable is not available. </simpara> </listitem> </varlistentry> <varlistentry> <term>$HTTP_COOKIE_VARS</term> <listitem> <simpara> An associative array of variables passed to the current script via HTTP cookies. </simpara> </listitem> </varlistentry> <varlistentry> <term>$_COOKIE</term> <listitem> <simpara> An associative array of variables passed to the current script via HTTP cookies. Automatically global in any scope. Introduced in PHP 4.1.0. </simpara> </listitem> </varlistentry> <varlistentry> <term>$HTTP_GET_VARS</term> <listitem> <simpara> An associative array of variables passed to the current script via the HTTP GET method. </simpara> </listitem> </varlistentry> <varlistentry> <term>$_GET</term> <listitem> <simpara> An associative array of variables passed to the current script via the HTTP GET method. Automatically global in any scope. Introduced in PHP 4.1.0. </simpara> </listitem> </varlistentry> <varlistentry> <term>$HTTP_POST_VARS</term> <listitem> <simpara> An associative array of variables passed to the current script via the HTTP POST method. </simpara> </listitem> </varlistentry> <varlistentry> <term>$_POST</term> <listitem> <simpara> An associative array of variables passed to the current script via the HTTP POST method. Automatically global in any scope. Introduced in PHP 4.1.0. </simpara> </listitem> </varlistentry> <varlistentry> <term>$HTTP_POST_FILES</term> <listitem> <simpara> An associative array of variables containing information about files uploaded via the HTTP POST method. See <link linkend="features.file-upload.post-method">POST method uploads</link> for information on the contents of <varname>$HTTP_POST_FILES</varname>. Introduced in 4.0.0. </simpara> </listitem> </varlistentry> <varlistentry> <term>$_FILES</term> <listitem> <simpara> An associative array of variables containing information about files uploaded via the HTTP POST method. See <link linkend="features.file-upload.post-method">POST method uploads</link> for information on the contents of <varname>$_FILES</varname>. Automatically global in any scope. Introduced in PHP 4.1.0. </simpara> </listitem> </varlistentry> <varlistentry> <term>$HTTP_ENV_VARS</term> <listitem> <simpara> An associative array of variables passed to the current script via the parent environment. </simpara> </listitem> </varlistentry> <varlistentry> <term>$_ENV</term> <listitem> <simpara> An associative array of variables passed to the current script via the parent environment. Automagically global in any scope. Introduced in PHP 4.1.0. </simpara> </listitem> </varlistentry> <varlistentry> <term>$HTTP_SERVER_VARS</term> <listitem> <simpara> An associative array of variables passed to the current script from the HTTP server. These variables are analogous to the Apache variables described above. </simpara> </listitem> </varlistentry> <varlistentry> <term>$_SERVER</term> <listitem> <simpara> An associative array of variables passed to the current script from the HTTP server. These variables are analogous to the Apache variables described above. Automatically global in any scope. Introduced in PHP 4.1.0. </simpara> </listitem> </varlistentry> <varlistentry> <term>$HTTP_SESSION_VARS</term> <listitem> <simpara> An associative array of session variables passed to the current script. </simpara> </listitem> </varlistentry> <varlistentry> <term>$_SESSION</term> <listitem> <simpara> An associative array of session variables passed to the current script. Automatically global in any scope. Creating new entries in the $_SESSION array will automatically register them as session variables, as if you called <function>session_register</function>. Introduced in PHP 4.1.0. </simpara> </listitem> </varlistentry> <varlistentry> <term>$_REQUEST</term> <listitem> <simpara> An associative array merged from the GET, POST, and Cookie variables. In other words - all the information that is coming from the user, and that from a security point of view, cannot be trusted. Automatically global in any scope. Introduced in PHP 4.1.0. </simpara> </listitem> </varlistentry> </variablelist> </para> </sect2> </sect1> <sect1 id="language.variables.scope"> <title>Variable scope</title> <simpara> The scope of a variable is the context within which it is defined. For the most part all PHP variables only have a single scope. This single scope spans included and required files as well. For example: </simpara> <informalexample> <programlisting role="php"> <![CDATA[ $a = 1; include "b.inc"; ]]> </programlisting> </informalexample> <simpara> Here the <varname>$a</varname> variable will be available within the included <filename>b.inc</filename> script. However, within user-defined functions a local function scope is introduced. Any variable used inside a function is by default limited to the local function scope. For example: </simpara> <informalexample> <programlisting role="php"> <![CDATA[ $a = 1; /* global scope */ function Test() { echo $a; /* reference to local scope variable */ } Test(); ]]> </programlisting> </informalexample> <simpara> This script will not produce any output because the echo statement refers to a local version of the <varname>$a</varname> variable, and it has not been assigned a value within this scope. You may notice that this is a little bit different from the C language in that global variables in C are automatically available to functions unless specifically overridden by a local definition. This can cause some problems in that people may inadvertently change a global variable. In PHP global variables must be declared global inside a function if they are going to be used in that function. An example: </simpara> <informalexample> <programlisting role="php"> <![CDATA[ $a = 1; $b = 2; function Sum() { global $a, $b; $b = $a + $b; } Sum(); echo $b; ]]> </programlisting> </informalexample> <simpara> The above script will output "3". By declaring <varname>$a</varname> and <varname>$b</varname> global within the function, all references to either variable will refer to the global version. There is no limit to the number of global variables that can be manipulated by a function. </simpara> <simpara> A second way to access variables from the global scope is to use the special PHP-defined <varname>$GLOBALS</varname> array. The previous example can be rewritten as: </simpara> <informalexample> <programlisting role="php"> <![CDATA[ $a = 1; $b = 2; function Sum() { $GLOBALS["b"] = $GLOBALS["a"] + $GLOBALS["b"]; } Sum(); echo $b; ]]> </programlisting> </informalexample> <simpara> The <varname>$GLOBALS</varname> array is an associative array with the name of the global variable being the key and the contents of that variable being the value of the array element. </simpara> <simpara> Another important feature of variable scoping is the <emphasis>static</emphasis> variable. A static variable exists only in a local function scope, but it does not lose its value when program execution leaves this scope. Consider the following example: </simpara> <informalexample> <programlisting role="php"> <![CDATA[ function Test () { $a = 0; echo $a; $a++; } ]]> </programlisting> </informalexample> <simpara> This function is quite useless since every time it is called it sets <varname>$a</varname> to <literal>0</literal> and prints "0". The <varname>$a</varname>++ which increments the variable serves no purpose since as soon as the function exits the <varname>$a</varname> variable disappears. To make a useful counting function which will not lose track of the current count, the <varname>$a</varname> variable is declared static: </simpara> <informalexample> <programlisting role="php"> <![CDATA[ function Test() { static $a = 0; echo $a; $a++; } ]]> </programlisting> </informalexample> <simpara> Now, every time the Test() function is called it will print the value of <varname>$a</varname> and increment it. </simpara> <simpara> Static variables also provide one way to deal with recursive functions. A recursive function is one which calls itself. Care must be taken when writing a recursive function because it is possible to make it recurse indefinitely. You must make sure you have an adequate way of terminating the recursion. The following simple function recursively counts to 10, using the static variable <varname>$count</varname> to know when to stop: </simpara> <informalexample> <programlisting role="php"> <![CDATA[ function Test() { static $count = 0; $count++; echo $count; if ($count < 10) { Test (); } $count--; } ]]> </programlisting> </informalexample> </sect1> <sect1 id="language.variables.variable"> <title>Variable variables</title> <simpara> Sometimes it is convenient to be able to have variable variable names. That is, a variable name which can be set and used dynamically. A normal variable is set with a statement such as: </simpara> <informalexample> <programlisting role="php"> <![CDATA[ $a = "hello"; ]]> </programlisting> </informalexample> <simpara> A variable variable takes the value of a variable and treats that as the name of a variable. In the above example, <emphasis>hello</emphasis>, can be used as the name of a variable by using two dollar signs. i.e. </simpara> <informalexample> <programlisting role="php"> <![CDATA[ $$a = "world"; ]]> </programlisting> </informalexample> <simpara> At this point two variables have been defined and stored in the PHP symbol tree: <varname>$a</varname> with contents "hello" and <varname>$hello</varname> with contents "world". Therefore, this statement: </simpara> <informalexample> <programlisting role="php"> <![CDATA[ echo "$a ${$a}"; ]]> </programlisting> </informalexample> <simpara> produces the exact same output as: </simpara> <informalexample> <programlisting role="php"> <![CDATA[ echo "$a $hello"; ]]> </programlisting> </informalexample> <simpara> i.e. they both produce: <computeroutput>hello world</computeroutput>. </simpara> <simpara> In order to use variable variables with arrays, you have to resolve an ambiguity problem. That is, if you write <varname>$$a[1]</varname> then the parser needs to know if you meant to use <varname>$a[1]</varname> as a variable, or if you wanted <varname>$$a</varname> as the variable and then the [1] index from that variable. The syntax for resolving this ambiguity is: <varname>${$a[1]}</varname> for the first case and <varname>${$a}[1]</varname> for the second. </simpara> </sect1> <sect1 id="language.variables.external"> <title>Variables from outside PHP</title> <sect2 id="language.variables.external.form"> <title>HTML Forms (GET and POST)</title> <simpara> 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 <link linkend="ini.track-vars">track_vars</link> configuration option is turned on, then these variables will be located in the associative arrays <varname>$HTTP_POST_VARS</varname>, <varname>$HTTP_GET_VARS</varname>, and/or <varname>$HTTP_POST_FILES</varname>, according to the source of the variable in question. </simpara> <para> For more information on these variables, please read <link linkend="language.variables.predefined">Predefined variables</link>. </para> <para> <example> <title>Simple form variable</title> <programlisting role="php"> <![CDATA[ <form action="foo.php" method="post"> Name: <input type="text" name="username"><br> <input type="submit"> </form> ]]> </programlisting> </example> </para> <para> When the above form is submitted, the value from the text input will be available in <varname>$HTTP_POST_VARS['username']</varname>. If the <link linkend="ini.register-globals">register_globals</link> configuration directive is turned on, then the variable will also be available as <varname>$username</varname> in the global scope. </para> <note> <para> The <link linkend="ini.magic-quotes-gpc">magic_quotes_gpc</link> configuration directive affects Get, Post and Cookie values. If turned on, value (It's "PHP!") will automagically become (It\'s \"PHP!\"). Escaping is needed for DB insertion. Also see <function>addslashes</function>, <function>stripslashes</function> and <link linkend="ini.magic-quotes-sybase">magic_quotes_sybase</link>. </para> </note> <simpara> PHP also understands arrays in the context of form variables (see the <link linkend="faq.html">related faq</link>). You may, for example, group related variables together, or use this feature to retrieve values from a multiple select input: </simpara> <para> <example> <title>More complex form variables</title> <programlisting role="php"> <![CDATA[ <form action="array.php" 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 value="guinness">Guinness <option value="stuttgarter">Stuttgarter Schwabenbräu </select> <input type="submit"> </form> ]]> </programlisting> </example> </para> <para> In PHP 3, the array form variable usage is limited to single-dimensional arrays. In PHP 4, no such restriction applies. </para> <sect3 id="language.variables.external.form.submit"> <title>IMAGE SUBMIT variable names</title> <simpara> When submitting a form, it is possible to use an image instead of the standard submit button with a tag like:</simpara> <informalexample> <programlisting role="php"> <![CDATA[ <input type="image" src="image.gif" name="sub"> ]]> </programlisting> </informalexample> <simpara> 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. </simpara> </sect3> </sect2> <sect2 id="language.variables.external.cookies"> <title>HTTP Cookies</title> <simpara> PHP transparently supports HTTP cookies as defined by <ulink url="&spec.cookies;">Netscape's Spec</ulink>. Cookies are a mechanism for storing data in the remote browser and thus tracking or identifying return users. You can set cookies using the <function>setcookie</function> 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 <function>header</function> function. Any cookies sent to you from the client will automatically be turned into a PHP variable just like GET and POST method data.</simpara> <simpara> If you wish to assign multiple values to a single cookie, just add <emphasis>[]</emphasis> to the cookie name. For example: </simpara> <informalexample> <programlisting role="php"> <![CDATA[ setcookie("MyCookie[]", "Testing", time()+3600); ]]> </programlisting> </informalexample> <simpara> 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. </simpara> <example> <title>SetCookie Example</title> <programlisting role="php"> <![CDATA[ $Count++; setcookie("Count", $Count, time()+3600); setcookie("Cart[$Count]", $item, time()+3600); ]]> </programlisting> </example> </sect2> <sect2 id="language.variables.external.environment"> <title>Environment variables</title> <para> PHP automatically makes environment variables available as normal PHP variables. <informalexample> <programlisting role="php"> <![CDATA[ echo $HOME; /* Shows the HOME environment variable, if set. */ ]]> </programlisting> </informalexample> </para> <para> 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 <function>getenv</function> function can be used for this. You can also set an environment variable with the <function>putenv</function> function. </para> </sect2> <sect2 id="language.variables.external.dot-in-names"> <title>Dots in incoming variable names</title> <para> 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: <programlisting role="php"> <![CDATA[ $varname.ext; /* invalid variable name */ ]]> </programlisting> Now, what the parser sees is a variable named <varname>$varname</varname>, 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. </para> <para> For this reason, it is important to note that PHP will automatically replace any dots in incoming variable names with underscores. </para> </sect2> <sect2 id="language.variables.determining-type-of"> <title>Determining variable types</title> <para> 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 <function>gettype</function>, <function>is_long</function>, <function>is_double</function>, <function>is_string</function>, <function>is_array</function>, and <function>is_object</function>. </para> </sect2> </sect1> </chapter> <!-- Keep this comment at the end of the file Local variables: mode: sgml sgml-omittag:t sgml-shorttag:t sgml-minimize-attributes:nil sgml-always-quote-attributes:t sgml-indent-step:1 sgml-indent-data:t indent-tabs-mode:nil sgml-parent-document:nil sgml-default-dtd-file:"../../manual.ced" sgml-exposed-tags:nil sgml-local-catalogs:nil sgml-local-ecat-files:nil End: vim600: syn=xml fen fdm=syntax fdl=2 si vim: et tw=78 syn=sgml vi: ts=1 sw=1 -->