language.variables.external.html

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     </p>

     <div class="informalexample">
      <div class="example-contents">
<div class="cdata"><pre>
&lt;input type=&quot;image&quot; src=&quot;image.gif&quot; name=&quot;sub&quot; /&gt;
</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, sub_x and sub_y. These contain the coordinates of the
      user click within the image.  The experienced may note that the
      actual variable names sent by the browser contains a period
      rather than an underscore, but PHP converts the period to an
      underscore automatically.
     </p>
    </div>

   </div>

   <div id="language.variables.external.cookies" class="sect2">
    <h3 class="title">HTTP Cookies</h3>

    <p class="simpara">
     PHP transparently supports HTTP cookies as defined by <a href="http://cgi.netscape.com/newsref/std/cookie_spec.html" class="link external">&raquo; Netscape&#039;s Spec</a>.  Cookies are a
     mechanism for storing data in the remote browser and thus
     tracking or identifying return users.  You can set cookies using
     the <a href="function.setcookie.html" class="function">setcookie()</a> 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 <a href="function.header.html" class="function">header()</a> function.  Cookie data 
     is then available in the appropriate cookie data arrays, such 
     as <var class="varname"><a href="reserved.variables.cookies.html" class="classname">$_COOKIE</a></var>, <var class="varname">$HTTP_COOKIE_VARS</var> 
     as well as in <var class="varname"><a href="reserved.variables.request.html" class="classname">$_REQUEST</a></var>.  See the 
     <a href="function.setcookie.html" class="function">setcookie()</a> 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">&lt;?php<br />&nbsp;&nbsp;setcookie</span><span style="color: #007700">(</span><span style="color: #DD0000">"MyCookie[foo]"</span><span style="color: #007700">,&nbsp;</span><span style="color: #DD0000">'Testing&nbsp;1'</span><span style="color: #007700">,&nbsp;</span><span style="color: #0000BB">time</span><span style="color: #007700">()+</span><span style="color: #0000BB">3600</span><span style="color: #007700">);<br />&nbsp;&nbsp;</span><span style="color: #0000BB">setcookie</span><span style="color: #007700">(</span><span style="color: #DD0000">"MyCookie[bar]"</span><span style="color: #007700">,&nbsp;</span><span style="color: #DD0000">'Testing&nbsp;2'</span><span style="color: #007700">,&nbsp;</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">?&gt;</span>
</span>
</code></div>
     </div>

    </div>
    
    <p class="simpara">
     That will create two separate cookies although MyCookie will now 
     be a single array in your script.  If you want to set just one cookie 
     with multiple values, consider using <a href="function.serialize.html" class="function">serialize()</a> or 
     <a href="function.explode.html" class="function">explode()</a> 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">
     <p><b>Example #4 A <a href="function.setcookie.html" class="function">setcookie()</a> example</b></p>
     <div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB">&lt;?php<br /></span><span style="color: #007700">if&nbsp;(isset(</span><span style="color: #0000BB">$_COOKIE</span><span style="color: #007700">[</span><span style="color: #DD0000">'count'</span><span style="color: #007700">]))&nbsp;{<br />&nbsp;&nbsp;&nbsp;&nbsp;</span><span style="color: #0000BB">$count&nbsp;</span><span style="color: #007700">=&nbsp;</span><span style="color: #0000BB">$_COOKIE</span><span style="color: #007700">[</span><span style="color: #DD0000">'count'</span><span style="color: #007700">]&nbsp;+&nbsp;</span><span style="color: #0000BB">1</span><span style="color: #007700">;<br />}&nbsp;else&nbsp;{<br />&nbsp;&nbsp;&nbsp;&nbsp;</span><span style="color: #0000BB">$count&nbsp;</span><span style="color: #007700">=&nbsp;</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">,&nbsp;</span><span style="color: #0000BB">$count</span><span style="color: #007700">,&nbsp;</span><span style="color: #0000BB">time</span><span style="color: #007700">()+</span><span style="color: #0000BB">3600</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">setcookie</span><span style="color: #007700">(</span><span style="color: #DD0000">"Cart[$count]"</span><span style="color: #007700">,&nbsp;</span><span style="color: #0000BB">$item</span><span style="color: #007700">,&nbsp;</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">?&gt;</span>
</span>
</code></div>
     </div>

    </div>

   </div>

   <div id="language.variables.external.dot-in-names" class="sect2">
    <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">&lt;?php<br />$varname</span><span style="color: #007700">.</span><span style="color: #0000BB">ext</span><span style="color: #007700">;&nbsp;&nbsp;</span><span style="color: #FF8000">/*&nbsp;invalid&nbsp;variable&nbsp;name&nbsp;*/<br /></span><span style="color: #0000BB">?&gt;</span>
</span>
</code></div>
     </div>

     Now, what the parser sees is a variable named
     <var class="varname">$varname</var>, followed by the string concatenation
     operator, followed by the barestring (i.e. unquoted string which
     doesn&#039;t match any known key or reserved words) &#039;ext&#039;. Obviously,
     this doesn&#039;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 id="language.variables.determining-type-of" class="sect2">
    <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:
     <a href="function.gettype.html" class="function">gettype()</a>, <a href="function.is-array.html" class="function">is_array()</a>,
     <a href="function.is-float.html" class="function">is_float()</a>, <a href="function.is-int.html" class="function">is_int()</a>,
     <a href="function.is-object.html" class="function">is_object()</a>, and
     <a href="function.is-string.html" class="function">is_string()</a>.  See also the chapter on 
     <a href="language.types.html" class="link">Types</a>.
    </p>
   </div>

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