Setting and Viewing Cookies with PHP
Here is a fun way to learn about cookies by setting them and
then viewing them.
First, let's set a cookie.
In a PHP web page, put these 14 lines of PHP code at the top
of the web page source code. There may be no characters, no
spaces, and no blank lines in the file above this PHP code:
In the above code, you may change:
-
The cookie's name. Cookies must have a name. It can
be any sequence of characters excluding semi-colon,
comma and white space.
-
The cookie's value. The value may be empty or
contain any sequence of characters. There is a limit
to how many characters the value may contain. The
entire cookie, cookie name, domain name, value,
etc., may be no more than 4k in size. So the
maximum size of the value by itself would
be some less than 4k.
-
The valid directory. This is the directory (and its
subdirectories) that the cookie may be read from.
"/" represents the document root, a cookie that can
be read from anywhere on the domain. "/books" would
mean the cookie can only be read from directory
/books and its subdirectories.
-
The number of days the cookie shall live. Specify 0
for a session cookie (a cookie that deletes when the
browser is closed). Otherwise, specify the number of
days.
The setcookie() function is the line that sets the cookie.
The other code lines prepare the variables for the function.
If you are familiar with PHP, you may wish to put values
directly into the function call and the variables dispensed
with. It would give you more control over exactly what
values are sent to the setcookie() function. For example,
the cookie lifetime doesn't have to be in days, but can be
specified in shorter blocks -- hours or even seconds. And
additional parameters may be sent to the function, such as
an indication that the cookie may be set and read only with
a secure connection.
The above paragraph is only for those having good
familiarity with PHP. For everybody else, simply pop the PHP
code into the web page, as is, or with some of the variables
changed.
Upload the web page with the cookie setting PHP code to your
server and load the page into your browser. When the page
loads into the browser, the cookie is set.
Note: When a cookie is set with PHP, the cookie will be
available to the browser at the *next* page load, not the
same page load as when the cookie was set. This is unlike
JavaScript, where the cookie is available immediately.
OK, now let's view the cookie.
These 5 lines of PHP code put anywhere within the body area
of a PHP web page will tell you what cookies the browser has
available:
Upload the page to your server and load the page into your
browser. It will list any cookies available for the directory
where the page is located.
The list of cookies is rather raw. But the information is
there. Code could be written to pretty the cookie display.
For further study, the cookies specification is at
http://wp.netscape.com/newsref/std/cookie_spec.html
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Will Bontrager
©Copyright 2007 Bontrager Connection, LLC Bontrager Connection, LLC
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