PHP Cookies
A cookie is often used to identify a user.
What is a Cookie?
A cookie is often used to identify a user. A cookie is a small file that the
server embeds on the user's computer. Each time the same computer requests a
page with a browser, it will send the cookie too. With PHP, you can both create
and retrieve cookie values.
How to Create a Cookie?
The setcookie() function is used to set a cookie.
Note: The setcookie() function must appear BEFORE the <html> tag.
Syntax
setcookie(name, value, expire, path, domain);
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Example 1
In the example below, we will create a cookie named "user" and assign the
value "Alex Porter" to it. We also specify that the cookie should expire after
one hour:
<?php
setcookie("user", "Alex Porter", time()+3600);
?>
<html>
.....
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Note: The value of the cookie is automatically URLencoded when
sending the cookie, and automatically decoded when received (to prevent
URLencoding, use setrawcookie() instead).
Example 2
You can also set the expiration time of the cookie in another way. It may be
easier than using seconds.
<?php
$expire=time()+60*60*24*30;
setcookie("user", "Alex Porter", $expire);
?>
<html>
.....
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In the example above the expiration time is set to a month (60 sec * 60
min * 24 hours * 30 days).
How to Retrieve a Cookie Value?
The PHP $_COOKIE variable is used to
retrieve a cookie value.
In the example below, we retrieve the value of the cookie named "user" and
display it on a page:
<?php
// Print a cookie
echo $_COOKIE["user"];
// A way to view all cookies
print_r($_COOKIE);
?>
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In the following example we use the isset() function to find out if a cookie
has been set:
<html>
<body>
<?php
if (isset($_COOKIE["user"]))
echo "Welcome " . $_COOKIE["user"] . "!<br />";
else
echo "Welcome guest!<br />";
?>
</body>
</html>
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How to Delete a Cookie?
When deleting a cookie you should assure that the expiration date is in the
past.
Delete example:
<?php
// set the expiration date to one hour ago
setcookie("user", "", time()-3600);
?>
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What if a Browser Does NOT Support Cookies?
If your application deals with browsers that do not support cookies, you will
have to use other methods to pass information from one page to another in your
application. One method is to pass the data through forms (forms and user input are described
earlier in this tutorial).
The form below passes the user input to "welcome.php" when the user clicks on
the "Submit" button:
<html>
<body>
<form action="welcome.php" method="post">
Name: <input type="text" name="name" />
Age: <input type="text" name="age" />
<input type="submit" />
</form>
</body>
</html>
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Retrieve the values in the "welcome.php" file like this:
<html>
<body>
Welcome <?php echo $_POST["name"]; ?>.<br />
You are <?php echo $_POST["age"]; ?> years old.
</body>
</html>
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