What Is A Cookie?
A cookie is a small amount of information sent by a Web server to a web browser and then sent back unchanged by the browser each time it accesses that server. HTTP cookies are used for authenticating, tracking, and maintaining specific information about users, such as site preferences and the contents of their electronic shopping carts. The term "cookie" is derived from "magic cookie", a well-known concept in computing which inspired both the idea and the name of HTTP cookies.
A cookie consists of a cookie name and cookie value.
How To Send A Cookie To The Browser?
If you want to sent a cookie to the browser when it comes to request your PHP page, you can use the setcookie( ) function. Note that you should call setcookie() function before any output statements. The following script shows you how to set cookies:
<?php
setcookie("LoginName","XYZ");
setcookie("PreferredColor","Blue");
print("2 cookies were delivered.\n");
?>
How To Receive A Cookie From The Browser?
If you know that a cookie has been sent to the browser when it was visiting the server previously, you can check the built-in $_COOKIE array, which contains all cookies that were sent by the server previously. The script below shows you how to pickup one cookie from the $_COOKIE and loop through all cookies in $_COOKIE:
<?php
if (isset($_COOKIE["LoginName"])) {
$loginName = $_COOKIE["LoginName"];
print("Received a cookie named as LoginName: ".$loginName."\n");
} else {
print("Did not received any cookie named as LoginName.\n");
}
print("All cookies received:\n");
foreach ($_COOKIE as $name => $value) {
print " $name = $value\n";
}
?>
How Cookies Are Transported From Servers To Browsers?
Cookies are transported from a Web server to a Web browser in the header area of the HTTP response message. Each cookie will be included in a separate "Set-Cookie:" header line in the following format:
Set-Cookie: name=value; expires=time; path=pathVal; domain=domainVal.
How Cookies Are Transported From Browsers To Servers?
Cookies are transported from a Web browser to a Web server in the header area of the HTTP request message. Each cookie will be included in a separate "Cookie:" header line in the following format:
GET / HTTP/1.1
Cookie: name1=value1
Cookie: name2=value2
Cookie: name3=value3
......
Accept: */*
Where Are The Persistent Cookies Stored On Your Computer?
The location and file names where persistent cookies are stored on your computer depend on which browser you are using. If you using Microsoft Internet Explorer, persistent cookies are stored in the \Documents and Settings\$user\Cookies directory. Cookies are stored in multiple cookie files with one file per Web server. Check your cookie directory on your local system, you will be surprised to see how many Web servers are setting persistent cookies to your computer.
How To Delete Cookie Files On Your Computer?
A simple way to delete cookie files on your computer is to use the function offered by the IE browser. The following tutorial exercise shows you how to delete cookie files created by IE:
• Open IE (Internet Explorer)
• Go to Options/Internet Options
• Click the Delete Cookies button on the options dialog window.
Check the cookie directory again. All cookie files should be deleted.
How Does Firefox Manage Cookies?
FireFox browser allows you to delete old cookies, and gives you options to keep persistent cookies in cookie files until they reach their expiration time. The following tutorial shows you how to manage cookies in FireFox:
• Run FireFox
• Go to Tools/Options
• Click Privacy and then Cookies
• Click the Clear button to delete all old cookies
• Change the Keep Cookies option to "until they expire" to allow persistent cookies to be store a cookie file.
What Are The Options To Transfer Session Ids?
Once a new session is created, its session ID must be transferred to the client browser and included in the next client request, so that the PHP engine can find the same session created by the same visitor. The PHP engine has two options to transfer the session ID to the client browser:
As URL parameter - The Session ID will be embedded in all URLs in the HTML document delivered to the client browser. When the visitor clicks any of those URLs, the session ID will be returned back to the Web server as part of the requesting URL.
As a cookie - The session ID will be delivered as a cookie to the client browser. When visitor requests any other pages on the Web server, the session ID will be returned back to the Web server also as a cookie.
The PHP engine is configured to use URL parameters for transferring session IDs by default.
Is It More Secure To Use Cookies To Transfer Session Ids?
yes, because attacking your Web site using URL parameters is much easier than using cookies.
So if you are the system administrator of your Web server, you should set session.use_only_cookies=1.
If your Web server is provided by a hosting service provider, ask them to set session.use_only_cookies=1.
How can PHP and Javascript interact?
PHP and Javascript cannot directly interact since PHP is a server side language and Javascript is a client-side language. However, we can exchange variables since PHP can generate Javascript code to be executed by the browser and it is possible to pass specific variables back to PHP via the URL.
What is needed to be able to use image function?
GD library is needed to execute image functions.
What is the use of the function 'imagetypes()'?
imagetypes() gives the image format and types supported by the current version of GD-PHP.
A cookie is a small amount of information sent by a Web server to a web browser and then sent back unchanged by the browser each time it accesses that server. HTTP cookies are used for authenticating, tracking, and maintaining specific information about users, such as site preferences and the contents of their electronic shopping carts. The term "cookie" is derived from "magic cookie", a well-known concept in computing which inspired both the idea and the name of HTTP cookies.
A cookie consists of a cookie name and cookie value.
How To Send A Cookie To The Browser?
If you want to sent a cookie to the browser when it comes to request your PHP page, you can use the setcookie( ) function. Note that you should call setcookie() function before any output statements. The following script shows you how to set cookies:
<?php
setcookie("LoginName","XYZ");
setcookie("PreferredColor","Blue");
print("2 cookies were delivered.\n");
?>
How To Receive A Cookie From The Browser?
If you know that a cookie has been sent to the browser when it was visiting the server previously, you can check the built-in $_COOKIE array, which contains all cookies that were sent by the server previously. The script below shows you how to pickup one cookie from the $_COOKIE and loop through all cookies in $_COOKIE:
<?php
if (isset($_COOKIE["LoginName"])) {
$loginName = $_COOKIE["LoginName"];
print("Received a cookie named as LoginName: ".$loginName."\n");
} else {
print("Did not received any cookie named as LoginName.\n");
}
print("All cookies received:\n");
foreach ($_COOKIE as $name => $value) {
print " $name = $value\n";
}
?>
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How Cookies Are Transported From Servers To Browsers?
Cookies are transported from a Web server to a Web browser in the header area of the HTTP response message. Each cookie will be included in a separate "Set-Cookie:" header line in the following format:
Set-Cookie: name=value; expires=time; path=pathVal; domain=domainVal.
How Cookies Are Transported From Browsers To Servers?
Cookies are transported from a Web browser to a Web server in the header area of the HTTP request message. Each cookie will be included in a separate "Cookie:" header line in the following format:
GET / HTTP/1.1
Cookie: name1=value1
Cookie: name2=value2
Cookie: name3=value3
......
Accept: */*
Where Are The Persistent Cookies Stored On Your Computer?
The location and file names where persistent cookies are stored on your computer depend on which browser you are using. If you using Microsoft Internet Explorer, persistent cookies are stored in the \Documents and Settings\$user\Cookies directory. Cookies are stored in multiple cookie files with one file per Web server. Check your cookie directory on your local system, you will be surprised to see how many Web servers are setting persistent cookies to your computer.
How To Delete Cookie Files On Your Computer?
A simple way to delete cookie files on your computer is to use the function offered by the IE browser. The following tutorial exercise shows you how to delete cookie files created by IE:
• Open IE (Internet Explorer)
• Go to Options/Internet Options
• Click the Delete Cookies button on the options dialog window.
Check the cookie directory again. All cookie files should be deleted.
How Does Firefox Manage Cookies?
FireFox browser allows you to delete old cookies, and gives you options to keep persistent cookies in cookie files until they reach their expiration time. The following tutorial shows you how to manage cookies in FireFox:
• Run FireFox
• Go to Tools/Options
• Click Privacy and then Cookies
• Click the Clear button to delete all old cookies
• Change the Keep Cookies option to "until they expire" to allow persistent cookies to be store a cookie file.
What Are The Options To Transfer Session Ids?
Once a new session is created, its session ID must be transferred to the client browser and included in the next client request, so that the PHP engine can find the same session created by the same visitor. The PHP engine has two options to transfer the session ID to the client browser:
As URL parameter - The Session ID will be embedded in all URLs in the HTML document delivered to the client browser. When the visitor clicks any of those URLs, the session ID will be returned back to the Web server as part of the requesting URL.
As a cookie - The session ID will be delivered as a cookie to the client browser. When visitor requests any other pages on the Web server, the session ID will be returned back to the Web server also as a cookie.
The PHP engine is configured to use URL parameters for transferring session IDs by default.
Is It More Secure To Use Cookies To Transfer Session Ids?
yes, because attacking your Web site using URL parameters is much easier than using cookies.
So if you are the system administrator of your Web server, you should set session.use_only_cookies=1.
If your Web server is provided by a hosting service provider, ask them to set session.use_only_cookies=1.
How can PHP and Javascript interact?
PHP and Javascript cannot directly interact since PHP is a server side language and Javascript is a client-side language. However, we can exchange variables since PHP can generate Javascript code to be executed by the browser and it is possible to pass specific variables back to PHP via the URL.
What is needed to be able to use image function?
GD library is needed to execute image functions.
What is the use of the function 'imagetypes()'?
imagetypes() gives the image format and types supported by the current version of GD-PHP.
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