Detailed explanation of the use of Cookie and Session in PHP5_PHP Tutorial

1. Introduction and differences between Cookie and Session

In many cases, we need to track visitors’ activities throughout the website and automatically or semi-automatically identify their identities (that is, functions such as website login). At this time, we often use cookies. Use Session to track and judge.

Difference

Session information is stored on the server side, but the session id is stored in the client cookie. Of course, PHP's session storage methods are diverse, so it can be tracked even if cookies are disabled

Cookies are completely kept on the client, such as: IE firefox. When the client disables cookies, it will no longer be able to be used

2. Cookie configuration and application

Setcookie(string name, string value, int expire,string path, string domain, int secure);
where name is the cookie variable name identifier. You can use it in PHP just like an ordinary variable name. Reference cookie variable. value is the initial value of the cookie variable, expire represents the validity time of the cookie variable; path represents the relevant path of the cookie variable; domain represents the website of the cookie variable; secure is valid only when https is securely transmitted.

SetCookie("Cookie", "cookievalue",time()+3600, "/forum", ".php100.com", 1);
Receive and process Cookie
PHP receives and processes Cookies The processing support is very good, it is completely automatic, it is the same as the principle of FORM variables, and it is very simple.
For example, if you set a cookie named MyCookier, PHP will automatically analyze it from the HTTP header received by the WEB server and form a variable like an ordinary variable named $myCookie. The value of this variable is the cookie. value. The same applies to arrays. Another way is to reference PHP's global variable $HTTP_COOKIE_VARS array.
Examples are as follows: (assuming these have been set in previous pages and are still valid)

echo $MyCookie;
echo $CookieArray[0];
echo $_COOKIE["MyCookie"];
echo $HTTP_COOKIE_VARS["MyCookie"];
Delete Cookie

To delete an existing cookie, there are two ways:

1. SetCookie("Cookie", "");
2. SetCookie("Cookie", "value" , ​​time()-1 / time() );

Restrictions on the use of cookies

1. It must be set before the content of the HTML file is output;
2. Different browsers handle cookies inconsistently, and sometimes incorrect results will occur.
3. The restriction is on the client side. The maximum number of cookies that can be created by a browser is 30, and each cookie cannot exceed 4KB. The total number of cookies that can be set by each WEB site cannot exceed 20.

3. Session configuration and application