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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 for 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
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>
<body>
</body>
</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).
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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