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</div><hr /><div id="language.variables.external" class="sect1">
<h2 class="title">Variables From External Sources</h2>
<div class="sect2" id="language.variables.external.form">
<h3 class="title">HTML Forms (GET and POST)</h3>
<p class="simpara">
When a form is submitted to a PHP script, the information from
that form is automatically made available to the script. There
are many ways to access this information, for example:
</p>
<p class="para">
<div class="example" id="example-108">
<p><strong>Example #1 A simple HTML form</strong></p>
<div class="example-contents">
<div class="htmlcode"><pre class="htmlcode"><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></pre>
</div>
</div>
</div>
</p>
<p class="para">
Depending on your particular setup and personal preferences, there
are many ways to access data from your HTML forms. Some examples are:
</p>
<p class="para">
<div class="example" id="example-109">
<p><strong>Example #2 Accessing data from a simple POST HTML form</strong></p>
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB"><?php <br /></span><span style="color: #FF8000">// Available since PHP 4.1.0<br /><br /> </span><span style="color: #007700">echo </span><span style="color: #0000BB">$_POST</span><span style="color: #007700">[</span><span style="color: #DD0000">'username'</span><span style="color: #007700">];<br /> echo </span><span style="color: #0000BB">$_REQUEST</span><span style="color: #007700">[</span><span style="color: #DD0000">'username'</span><span style="color: #007700">];<br /><br /> </span><span style="color: #0000BB">import_request_variables</span><span style="color: #007700">(</span><span style="color: #DD0000">'p'</span><span style="color: #007700">, </span><span style="color: #DD0000">'p_'</span><span style="color: #007700">);<br /> echo </span><span style="color: #0000BB">$p_username</span><span style="color: #007700">;<br /><br /></span><span style="color: #FF8000">// As of PHP 5.0.0, these long predefined variables can be<br />// disabled with the register_long_arrays directive.<br /><br /> </span><span style="color: #007700">echo </span><span style="color: #0000BB">$HTTP_POST_VARS</span><span style="color: #007700">[</span><span style="color: #DD0000">'username'</span><span style="color: #007700">];<br /><br /></span><span style="color: #FF8000">// Available if the PHP directive register_globals = on. As of <br />// PHP 4.2.0 the default value of register_globals = off.<br />// Using/relying on this method is not preferred.<br /><br /> </span><span style="color: #007700">echo </span><span style="color: #0000BB">$username</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">?></span>
</span>
</code></div>
</div>
</div>
</p>
<p class="para">
Using a GET form is similar except you'll use the appropriate
GET predefined variable instead. GET also applies to the
<em>QUERY_STRING</em> (the information after the '?' in a URL). So,
for example, <em>http://www.example.com/test.php?id=3</em>
contains GET data which is accessible with <var class="varname"><var class="varname"><a href="reserved.variables.get.html" class="classname">$_GET['id']</a></var></var>.
See also <var class="varname"><var class="varname"><a href="reserved.variables.request.html" class="classname">$_REQUEST</a></var></var> and
<span class="function"><a href="function.import-request-variables.html" class="function">import_request_variables()</a></span>.
</p>
<blockquote class="note"><p><strong class="note">Note</strong>:
<p class="para">
<a href="language.variables.superglobals.html" class="link">Superglobal arrays</a>,
like <var class="varname"><var class="varname"><a href="reserved.variables.post.html" class="classname">$_POST</a></var></var> and <var class="varname"><var class="varname"><a href="reserved.variables.get.html" class="classname">$_GET</a></var></var>, became
available in PHP 4.1.0
</p>
</p></blockquote>
<blockquote class="note"><p><strong class="note">Note</strong>:
<p class="para">
Dots and spaces in variable names are converted to underscores. For
example <em><input name="a.b" /></em> becomes
<em>$_REQUEST["a_b"]</em>.
</p>
</p></blockquote>
<p class="para">
As shown, before PHP 4.2.0 the default value for <a href="ini.core.html#ini.register-globals" class="link">register_globals</a>
was <em class="emphasis">on</em>. The PHP
community is encouraging all to not rely on this directive
as it's preferred to assume it's <em class="emphasis">off</em> and code
accordingly.
</p>
<blockquote class="note"><p><strong class="note">Note</strong>:
<p class="para">
The <a href="info.configuration.html#ini.magic-quotes-gpc" class="link">magic_quotes_gpc</a>
configuration directive affects Get, Post and Cookie values. If
turned on, value (It's "PHP!") will automagically become (It\'s \"PHP!\").
It was deemed that this was needed for escaping for DB insertion circa a
decade ago and is a legacy feature now that should be disabled. See also
<span class="function"><a href="function.addslashes.html" class="function">addslashes()</a></span>, <span class="function"><a href="function.stripslashes.html" class="function">stripslashes()</a></span> and
<a href="sybase.configuration.html#ini.magic-quotes-sybase" class="link">magic_quotes_sybase</a>.
</p>
</p></blockquote>
<p class="simpara">
PHP also understands arrays in the context of form variables
(see the <a href="faq.html.html" class="link">related faq</a>). You may,
for example, group related variables together, or use this
feature to retrieve values from a multiple select input. For
example, let's post a form to itself and upon submission display
the data:
</p>
<p class="para">
<div class="example" id="example-110">
<p><strong>Example #3 More complex form variables</strong></p>
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB"><?php<br /></span><span style="color: #007700">if (</span><span style="color: #0000BB">$_POST</span><span style="color: #007700">) {<br /> echo </span><span style="color: #DD0000">'<pre>'</span><span style="color: #007700">;<br /> echo </span><span style="color: #0000BB">htmlspecialchars</span><span style="color: #007700">(</span><span style="color: #0000BB">print_r</span><span style="color: #007700">(</span><span style="color: #0000BB">$_POST</span><span style="color: #007700">, </span><span style="color: #0000BB">true</span><span style="color: #007700">));<br /> echo </span><span style="color: #DD0000">'</pre>'</span><span style="color: #007700">;<br />}<br /></span><span style="color: #0000BB">?><br /></span><form action="" method="post"><br /> Name: <input type="text" name="personal[name]" /><br /><br /> Email: <input type="text" name="personal[email]" /><br /><br /> Beer: <br /><br /> <select multiple name="beer[]"><br /> <option value="warthog">Warthog</option><br /> <option value="guinness">Guinness</option><br /> <option value="stuttgarter">Stuttgarter Schwabenbräu</option><br /> </select><br /><br /> <input type="submit" value="submit me!" /><br /></form></span>
</code></div>
</div>
</div>
</p>
<div class="sect3" id="language.variables.external.form.submit">
<h4 class="title">IMAGE SUBMIT variable names</h4>
<p class="simpara">
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">
<div class="example-contents">
<div class="htmlcode"><pre class="htmlcode"><input type="image" src="image.gif" name="sub" /></pre>
</div>
</div>
</div>
<p class="simpara">
When the user clicks somewhere on the image, the accompanying
form will be transmitted to the server with two additional
variables, <var class="varname"><var class="varname">sub_x</var></var> and <var class="varname"><var class="varname">sub_y</var></var>.
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" id="language.variables.external.cookies">
<h3 class="title">HTTP Cookies</h3>
<p class="simpara">
PHP transparently supports HTTP cookies as defined by <a href="http://www.faqs.org/rfcs/rfc6265" class="link external">» RFC 6265</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 <span class="function"><a href="function.setcookie.html" class="function">setcookie()</a></span> 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 <span class="function"><a href="function.header.html" class="function">header()</a></span> function. Cookie data
is then available in the appropriate cookie data arrays, such
as <var class="varname"><var class="varname"><a href="reserved.variables.cookies.html" class="classname">$_COOKIE</a></var></var>, <var class="varname"><var class="varname">$HTTP_COOKIE_VARS</var></var>
as well as in <var class="varname"><var class="varname"><a href="reserved.variables.request.html" class="classname">$_REQUEST</a></var></var>. See the
<span class="function"><a href="function.setcookie.html" class="function">setcookie()</a></span> manual page for more details and
examples.
</p>
<p class="simpara">
If you wish to assign multiple values to a single cookie variable, you
may assign it as an array. For example:
</p>
<div class="informalexample">
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB"><?php<br /> setcookie</span><span style="color: #007700">(</span><span style="color: #DD0000">"MyCookie[foo]"</span><span style="color: #007700">, </span><span style="color: #DD0000">'Testing 1'</span><span style="color: #007700">, </span><span style="color: #0000BB">time</span><span style="color: #007700">()+</span><span style="color: #0000BB">3600</span><span style="color: #007700">);<br /> </span><span style="color: #0000BB">setcookie</span><span style="color: #007700">(</span><span style="color: #DD0000">"MyCookie[bar]"</span><span style="color: #007700">, </span><span style="color: #DD0000">'Testing 2'</span><span style="color: #007700">, </span><span style="color: #0000BB">time</span><span style="color: #007700">()+</span><span style="color: #0000BB">3600</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">?></span>
</span>
</code></div>
</div>
</div>
<p class="simpara">
That will create two separate cookies although <var class="varname"><var class="varname">MyCookie</var></var> will now
be a single array in your script. If you want to set just one cookie
with multiple values, consider using <span class="function"><a href="function.serialize.html" class="function">serialize()</a></span> or
<span class="function"><a href="function.explode.html" class="function">explode()</a></span> on the value first.
</p>
<p class="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.
</p>
<div class="example" id="example-111">
<p><strong>Example #4 A <span class="function"><a href="function.setcookie.html" class="function">setcookie()</a></span> example</strong></p>
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB"><?php<br /></span><span style="color: #007700">if (isset(</span><span style="color: #0000BB">$_COOKIE</span><span style="color: #007700">[</span><span style="color: #DD0000">'count'</span><span style="color: #007700">])) {<br /> </span><span style="color: #0000BB">$count </span><span style="color: #007700">= </span><span style="color: #0000BB">$_COOKIE</span><span style="color: #007700">[</span><span style="color: #DD0000">'count'</span><span style="color: #007700">] + </span><span style="color: #0000BB">1</span><span style="color: #007700">;<br />} else {<br /> </span><span style="color: #0000BB">$count </span><span style="color: #007700">= </span><span style="color: #0000BB">1</span><span style="color: #007700">;<br />}<br /></span><span style="color: #0000BB">setcookie</span><span style="color: #007700">(</span><span style="color: #DD0000">'count'</span><span style="color: #007700">, </span><span style="color: #0000BB">$count</span><span style="color: #007700">, </span><span style="color: #0000BB">time</span><span style="color: #007700">()+</span><span style="color: #0000BB">3600</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">setcookie</span><span style="color: #007700">(</span><span style="color: #DD0000">"Cart[</span><span style="color: #0000BB">$count</span><span style="color: #DD0000">]"</span><span style="color: #007700">, </span><span style="color: #0000BB">$item</span><span style="color: #007700">, </span><span style="color: #0000BB">time</span><span style="color: #007700">()+</span><span style="color: #0000BB">3600</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">?></span>
</span>
</code></div>
</div>
</div>
</div>
<div class="sect2" id="language.variables.external.dot-in-names">
<h3 class="title">Dots in incoming variable names</h3>
<p class="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:
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB"><?php<br />$varname</span><span style="color: #007700">.</span><span style="color: #0000BB">ext</span><span style="color: #007700">; </span><span style="color: #FF8000">/* invalid variable name */<br /></span><span style="color: #0000BB">?></span>
</span>
</code></div>
</div>
Now, what the parser sees is a variable named
<var class="varname"><var class="varname">$varname</var></var>, 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 class="para">
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" id="language.variables.determining-type-of">
<h3 class="title">Determining variable types</h3>
<p class="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, such as:
<span class="function"><a href="function.gettype.html" class="function">gettype()</a></span>, <span class="function"><a href="function.is-array.html" class="function">is_array()</a></span>,
<span class="function"><a href="function.is-float.html" class="function">is_float()</a></span>, <span class="function"><a href="function.is-int.html" class="function">is_int()</a></span>,
<span class="function"><a href="function.is-object.html" class="function">is_object()</a></span>, and
<span class="function"><a href="function.is-string.html" class="function">is_string()</a></span>. See also the chapter on
<a href="language.types.html" class="link">Types</a>.
</p>
</div>
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