What are the functions and uses of cookies in php?

Function of Cookie

Cookie is generated by the server and sent to User-Agent (usually a browser), and the browser will store the Cookie key /value is saved to a text file in a directory, and the cookie will be sent to the server the next time the same website is requested (provided that the browser is set to enable cookies). Cookie names and values ​​can be defined by the server-side developer, so that the server can know whether the user is a legitimate user and whether he needs to log in again, etc. The server can set or read the information contained in Cookies to maintain the status of the user's session with the server.

Web servers can filter or maintain this information through the information contained in Cookies to determine the status during HTTP transmission.

Cookies are commonly used in the following three aspects:

Record certain information about visitors. For example, cookies can be used to record the number of times a user visits a web page, or to record the information that has been entered. In addition, some websites can use cookies to automatically record the user name of the visitor's last login.

Passing variables between pages. The browser does not save any variable information on the current page. When the page is closed, all variable information on the page will disappear. If the user declares a variable id=6 and wants to pass this variable to another page, he can save the variable id in the form of a cookie, and then obtain the value of the variable by reading the cookie on the next page.

Store the viewed Internet pages in a temporary cookie file, which can improve the speed of future browsing.

Note: Generally do not use cookies to save data sets or other large amounts of data. Not all browsers support cookies, and the data information is stored in the client computer in the form of plain text, so it is best not to save sensitive, unencrypted data, otherwise it will affect the security of the network sex.

What are the uses of cookies?

The most fundamental purpose of cookies is to help Web sites save information about visitors. More generally, cookies are a way to maintain the continuity (that is, perform "state management") of a web application. The browser and the web server are always disconnected except for a brief period of actual information exchange, and each request a user sends to the web server is processed independently of all other requests. In most cases, however, it is necessary for the web server to recognize you when you request a page. For example, a Web server on a shopping site keeps track of each shopper so that the site can manage shopping carts and other user-related information. A cookie therefore acts like a business card, providing relevant identifying information that helps the application determine how to proceed.

Using cookies can serve a variety of purposes, all of which are designed to enable a website to remember you. For example, a site that implements polls can simply use cookies as a Boolean value to indicate whether your browser has already participated in the poll, thereby preventing you from voting again; while sites that require

user login can use Cookie to determine if you are already logged in so that you do not have to enter your credentials each time.

The above is the detailed content of What are the functions and uses of cookies in php?. For more information, please follow other related articles on the PHP Chinese website!