Cookie and Session operations in PHP

As Web applications become more and more popular, Cookie and Session have become an indispensable part of Web development. As a commonly used web development language, PHP has very good support for Cookies and Sessions. This article will introduce how to operate Cookie and Session in PHP.

1. The concept of Cookie

1.What is Cookie?

Cookie is a way to save data on the client side. The client can be a browser, a mobile terminal, etc. Cookies store data to the client by setting the Set-Cookie field in the HTTP response header. The browser will automatically save the data locally. The next time the server is requested, the data will be sent to the server. The server will use these data The data is processed logically accordingly. The data stored by cookies has a size limit, usually no more than 4KB.

2. The role of cookies

Cookies can be used in some scenarios: such as recording the user's login status, the user's browsing history, the user's shopping cart information, etc.

3. Cookie characteristics

Reliability: Cookie data is stored in the client browser and users can clear it at will, so Cookie data is not very reliable.

Security: Since the cookie data is stored on the client, others can easily see the cookie in the client, so the security of the cookie is poor.

2. Operating Cookies in PHP

1. Setting Cookies

To set Cookies in PHP, you can use the setcookie() function. The usage method is as follows:

setcookie(name, value, expire, path, domain, secure, httponly);

Parameter explanation:

• name: Cookie name.
• value: Cookie value.
• expire: Cookie expiration time, in seconds. The default is 0, which means closing the browser will fail.
• path: Optional parameter, specifying the path under which the cookie is valid. The default is '/', which means that this cookie can be accessed by pages under all paths.
• domain: Optional parameter, specifying the domain name under which the cookie is valid. The default is an empty string, which means it is valid under the current domain name.
• secure: Optional parameter, specifies whether the cookie can only be transmitted through HTTPS. Default is false.
• httponly: Optional parameter, specifies whether the cookie can only be transmitted through HTTP. Default is false.

Sample code:

setcookie('name', 'tom');
setcookie('age', '20', time()+3600); //设置过期时间为1小时

2. Get Cookie

To get Cookie in PHP, you can use the $_COOKIE super global variable to get it. The usage method is as follows:

$value = $_COOKIE['name'];

3. Delete Cookie

To delete Cookie in PHP, use the setcookie() function to set the expiration time to a past time:

setcookie('name', '', time()-3600); //将过期时间设置成一个过去的时间，即可删除Cookie

3. The concept of Session

1.What is Session?

Session is a way to save data on the server side. The server side can generate a Session ID. In PHP, the Session ID is stored on the client side through cookies by default, and can also be implemented through URL rewriting and other methods. Session does not have the size limit of Cookie in terms of storing data, but the performance of the server needs to be considered.

2. The role of Session

Session can be used in some scenarios: such as recording the user's login status, the user's shopping cart information, etc.

3.Session features

Reliability: Session data is stored on the server side and users cannot clear it at will, so Session data is relatively reliable.

Security: Since Session data is stored on the server side, the client cannot obtain Session data, so Session security is relatively good.

4. Operating Session in PHP

1. Open Session

Before using Session, you need to open Session. In PHP, you can open the Session through the following code:

session_start();

2. Set up the Session

To set up the Session in PHP, you can use the $_SESSION super global variable to operate. The usage method is as follows:

$_SESSION['name'] = 'tom';

3. Obtain Session

Obtaining Session in PHP can also be obtained using the $_SESSION super global variable. The usage method is the same as obtaining Cookie:

$value = $_SESSION['name'];

4. Delete Session

To delete a Session in PHP, you can use the unset() function:

unset($_SESSION['name']);

5. Destroy the Session

To delete a Session in PHP, you can use the session_destroy() function:

session_destroy();

Summary:

As can be seen from this article, Cookie and Session are important concepts in Web development, and they can be used to record information such as user status and browsing history. When using Cookies and Sessions, you need to pay attention to their characteristics and security to avoid causing security problems. In PHP, you can use the setcookie() function and the $_COOKIE superglobal variable to operate Cookies, and you can also use the session_start() function and the $_SESSION superglobal variable to operate Session.

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