A cookie is often used to identify a user.A cookie is a tiny little file on your client’s hard drive which contains data you have asked to be stored. Some clients specifically configure their browser to reject cookies, believing for one reason or another that they are malicious, and there is nothing you can do about this – that person’s browser will not be able to store your data. When creating cookies, you specify how long you want it to be valid for, and, once done, the cookie remains in place until that date, when it “expires”.
Cookies are automatically sent to the web server (and received/parsed by PHP) each time a user visits you. That means that once we place our cookie, our visitors’ browsers will automatically send the contents of that cookie across to us each time they view our messageboard index, and PHP will read the value into the $_COOKIE superglobal array. As cookies are sent each time, it is incredibly important not to store too much information there – they can really waste a lot of bandwidth.
The nice thing about cookies is that they are decentralised – you do not need to worry about creating databases to hold information or adding and removing rows, you just store the data and check whether it is set. As such, cookies are good for any pages where you have got a small amount of information to handle – usually this involves user preferences. For example, use cookies to store how users want their messageboard index sorting, what order they like their news printed, etc.
If you are storing information such as their email address, ICQ number, etc, you should probably use a database – data like that is generally stored for long periods of time, whereas cookies are usually more throwaway information. That said, if you are storing personal information in cookies, please take the time to encrypt it.
Setting Cookies with PHP:
PHP provided setcookie() function to set a cookie. This function requires upto six arguments and should be called before <html> tag. For each cookie this function has to be called separately.
setcookie(name, value, expire, path, domain, security);
Here is the detail of all the arguments:
Name – This sets the name of the cookie and is stored in an environment variable called HTTP_COOKIE_VARS. This variable is used while accessing cookies.
Value -This sets the value of the named variable and is the content that you actually want to store.
Expiry – This specify a future time in seconds since 00:00:00 GMT on 1st Jan 1970. After this time cookie will become inaccessible. If this parameter is not set then cookie will automatically expire when the Web Browser is closed.
Path -This specifies the directories for which the cookie is valid. A single forward slash character permits the cookie to be valid for all directories.
Domain – This can be used to specify the domain name in very large domains and must contain at least two periods to be valid. All cookies are only valid for the host and domain which created them.
Security – This can be set to 1 to specify that the cookie should only be sent by secure transmission using HTTPS otherwise set to 0 which mean cookie can be sent by regular HTTP.
Following example will create two cookies name and age these cookies will be expired after one hour.
<?php
setcookie(“name”, “John Watkin”, time()+3600, “/”,”", 0);
setcookie(“age”, “36″, time()+3600, “/”, “”, 0);
?>
<html>
<head>
<title>Setting Cookies with PHP</title>
</head>
<body>
<?php echo “Set Cookies”?>
</body>
</html>
Accessing Cookies with PHP
PHP provides many ways to access cookies.Simplest way is to use either $_COOKIE or $HTTP_COOKIE_VARS variables. Following example will access all the cookies set in above example.
<html>
<head>
<title>Accessing Cookies with PHP</title>
</head>
<body>
<?php
echo $_COOKIE["name"]. “<br />”;
/* is equivalent to */
echo $HTTP_COOKIE_VARS["name"]. “<br />”;
echo $_COOKIE["age"] . “<br />”;
/* is equivalent to */
echo $HTTP_COOKIE_VARS["name"] . “<br />”;
?>
</body>
</html>
You can use isset() function to check if a cookie is set or not.
<html>
<head>
<title>Accessing Cookies with PHP</title>
</head>
<body>
<?php
if( isset($_COOKIE["name"]))
echo “Welcome ” . $_COOKIE["name"] . “<br />”;
else
echo “Sorry… Not recognized” . “<br />”;
?>
</body>
</html>
Deleting Cookie with PHP
Officially, to delete a cookie you should call setcookie() with the name argument only but this does not always work well, however, and should not be relied on.
It is safest to set the cookie with a date that has already expired:
<?php
setcookie( “name”, “”, time()- 60, “/”,”", 0);
setcookie( “age”, “”, time()- 60, “/”,”", 0);
?>
<html>
<head>
<title>Deleting Cookies with PHP</title>
</head>
<body>
<?php echo “Deleted Cookies” ?>
</body>
</html>
Cookies are automatically sent to the web server (and received/parsed by PHP) each time a user visits you. That means that once we place our cookie, our visitors’ browsers will automatically send the contents of that cookie across to us each time they view our messageboard index, and PHP will read the value into the $_COOKIE superglobal array. As cookies are sent each time, it is incredibly important not to store too much information there – they can really waste a lot of bandwidth.
The nice thing about cookies is that they are decentralised – you do not need to worry about creating databases to hold information or adding and removing rows, you just store the data and check whether it is set. As such, cookies are good for any pages where you have got a small amount of information to handle – usually this involves user preferences. For example, use cookies to store how users want their messageboard index sorting, what order they like their news printed, etc.
If you are storing information such as their email address, ICQ number, etc, you should probably use a database – data like that is generally stored for long periods of time, whereas cookies are usually more throwaway information. That said, if you are storing personal information in cookies, please take the time to encrypt it.
Setting Cookies with PHP:
PHP provided setcookie() function to set a cookie. This function requires upto six arguments and should be called before <html> tag. For each cookie this function has to be called separately.
setcookie(name, value, expire, path, domain, security);
Here is the detail of all the arguments:
Name – This sets the name of the cookie and is stored in an environment variable called HTTP_COOKIE_VARS. This variable is used while accessing cookies.
Value -This sets the value of the named variable and is the content that you actually want to store.
Expiry – This specify a future time in seconds since 00:00:00 GMT on 1st Jan 1970. After this time cookie will become inaccessible. If this parameter is not set then cookie will automatically expire when the Web Browser is closed.
Path -This specifies the directories for which the cookie is valid. A single forward slash character permits the cookie to be valid for all directories.
Domain – This can be used to specify the domain name in very large domains and must contain at least two periods to be valid. All cookies are only valid for the host and domain which created them.
Security – This can be set to 1 to specify that the cookie should only be sent by secure transmission using HTTPS otherwise set to 0 which mean cookie can be sent by regular HTTP.
Following example will create two cookies name and age these cookies will be expired after one hour.
<?php
setcookie(“name”, “John Watkin”, time()+3600, “/”,”", 0);
setcookie(“age”, “36″, time()+3600, “/”, “”, 0);
?>
<html>
<head>
<title>Setting Cookies with PHP</title>
</head>
<body>
<?php echo “Set Cookies”?>
</body>
</html>
Accessing Cookies with PHP
PHP provides many ways to access cookies.Simplest way is to use either $_COOKIE or $HTTP_COOKIE_VARS variables. Following example will access all the cookies set in above example.
<html>
<head>
<title>Accessing Cookies with PHP</title>
</head>
<body>
<?php
echo $_COOKIE["name"]. “<br />”;
/* is equivalent to */
echo $HTTP_COOKIE_VARS["name"]. “<br />”;
echo $_COOKIE["age"] . “<br />”;
/* is equivalent to */
echo $HTTP_COOKIE_VARS["name"] . “<br />”;
?>
</body>
</html>
You can use isset() function to check if a cookie is set or not.
<html>
<head>
<title>Accessing Cookies with PHP</title>
</head>
<body>
<?php
if( isset($_COOKIE["name"]))
echo “Welcome ” . $_COOKIE["name"] . “<br />”;
else
echo “Sorry… Not recognized” . “<br />”;
?>
</body>
</html>
Deleting Cookie with PHP
Officially, to delete a cookie you should call setcookie() with the name argument only but this does not always work well, however, and should not be relied on.
It is safest to set the cookie with a date that has already expired:
<?php
setcookie( “name”, “”, time()- 60, “/”,”", 0);
setcookie( “age”, “”, time()- 60, “/”,”", 0);
?>
<html>
<head>
<title>Deleting Cookies with PHP</title>
</head>
<body>
<?php echo “Deleted Cookies” ?>
</body>
</html>
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