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);
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>
.....
Note: The
value of the cookie is automatically URLencoded when sending the cookie, and
automatically decoded when received (to prevent URLencoding, use setrawcookie()
instead).setcookie("user", "Alex Porter", time()+3600);
?>
<html>
.....
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", $expire);
?>
<html>
.....
In
the example above the expiration time is set to a month (60 sec * 60 min *
24 hours * 30 days).$expire=time()+60*60*24*30;
setcookie("user", "Alex Porter", $expire);
?>
<html>
.....
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);
?>
In
the following example we use the isset() function to find out if a cookie has
been set:// Print a cookie
echo $_COOKIE["user"];
// A way to view all cookies
print_r($_COOKIE);
?>
<html>
<body>
<?php
if (isset($_COOKIE["user"]))
echo "Welcome " . $_COOKIE["user"] . "!<br />";
else
echo "Welcome guest!<br />";
?>
</body>
</html>
<body>
<?php
if (isset($_COOKIE["user"]))
echo "Welcome " . $_COOKIE["user"] . "!<br />";
else
echo "Welcome guest!<br />";
?>
</body>
</html>
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);
?>
// set the expiration date to one hour ago
setcookie("user", "", time()-3600);
?>
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>
Retrieve
the values in the "welcome.php" file like this:<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>
<html>
<body>
Welcome <?php echo $_POST["name"]; ?>.<br />
You are <?php echo $_POST["age"]; ?> years old.
</body>
</html>
<body>
Welcome <?php echo $_POST["name"]; ?>.<br />
You are <?php echo $_POST["age"]; ?> years old.
</body>
</html>
