1.1 Principle:
Cookie is stored in the client information packet (a file)
1. The client sends a request to the server
2. The value of the server into the response header sent to the client
3. The browser automatically put information request to the server investment
1.2 Set Cookie
<PHP?
the setcookie ( 'name', 'Tom'); // name = tom into the response header
After the client has cookei information, each request server, the information will be automatically Cookie request header to the server is placed.
1.3 Gets the value of the Cookie
? <PHP
echo $ _COOKIE [ 'name']; // get the name from the request header is the name of the cookie
note:
After 1, close the browser, cookie disappeared. This cookie is called temporary cookie
2, cookie information is not shared among different browsers, not cross-browser.
1.4 Permanent Cookie
Note: After you close the browser cookie value does not disappear
Syntax: add to the cookie expiration time in a permanent cookie, the expiration time is the time to type timestamp
Time = Time $ () + 3600;
the setcookie ( 'name', 'Tom', $ Time); // cookie effective time is 3600 seconds
1.5Cookie active directory
The default cookie effective in the current directory and subdirectories
cookie disposed generally valid in the entire station
setcookie ( 'name', 'tom', 0, '/'); // / indicates the root directory
1.6 support subdomains
<PHP?
the setcookie ( 'name', 'Tom', 0, '/', 'baidu.com'); // baidu.com valid in the domain
?>
<A the href = "http://www.bb .baidu.com / bb.php "> Jump </a>
1.7 Is it safe transport
Https secure transmission is transmitted.
http and https can be transferred cookie by default
setcookie ( 'name', 'tom', 0, '/', '', true); // true means that only transmission is https
1.8 Is it safe to visit
By default, PHP and JS can access cookie
Secure access: PHP can access, JS is not the default false
<?php
setcookie('name','tom',0,'/','',false,true);
?>
<a href="/5-demo2.php">跳转</a>
1.9 Delete Cookie
? <PHP
// setcookie ( 'name', false); // delete the cookie method
// setcookie ( 'name'); // delete the cookie method two
setcookie ( 'name', 'tom ', time () - 1 ); // delete the cookie method three
Note: cookie can only save the numbers and strings.
The disadvantage of 1.10cookie
1, because you can see the value of the cookie in the browser, so security is low
2, since the numbers and only store a string, the poor controllability
3, because the data transmitted in the request header, the request for increased data load time.
4, because the data is stored in the browser, the browser stores a suction space is limited, typically 4K.