How to set cookie function in php

PHP is a popular server-side programming language with a wide range of applications. In web development, HTTP cookies are a commonly used mechanism to save data on the client side and send it to the server on subsequent requests. PHP provides a rich set of functions to manage cookies. This article will introduce how to set cookies using PHP.

1. What is Cookie

HTTP Cookie is a small data file that is stored in the web browser and used by the web server. Use cookies to track user data across multiple requests. The most common use of cookies is to store information about user authentication, personalization settings, and shopping cart status.

Cookies are managed by the browser. Each cookie has a name, a value and some attributes. Here are some common attributes of cookies:

1. Expiration time: When the cookie will expire and be deleted by the browser.
2. Domain name: The domain to which the cookie applies. For example: ".example.com" means that the cookie applies to all subdomains.
3. Path: The path where the cookie is applicable, for example: "/blog" means that the cookie is applicable to the "/blog" directory and any subdirectories in the application.
4. Security flag: Cookies will only be sent in HTTPS connections.

2. Setting Cookie

It is very simple to set Cookie using PHP. PHP provides the setcookie() function, which can set attributes such as cookie name, value, expiration time, domain, path, and security flag. The following is the syntax of the setcookie() function:

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

where name is the name of the Cookie; value is the value of the Cookie; expire (optional) is the expiration time of the cookie, expressed as a UNIX timestamp; path (optional) is the path to which the cookie is applicable; domain (optional) is the domain to which the cookie is applicable; secure (optional) indicates that the cookie can only be used on HTTPS Sent during connection.

For example, the following code will create a cookie named "username" with a value of "John", valid for 30 days, and sent under the entire domain name:

setcookie("username", "John", time()+60*60*24*30, "/", ".example.com", true, true);

On the client , the browser will display a cookie named "username" with the value "John".

3. Reading Cookie

Reading Cookie using PHP is also very simple. You can use the $_COOKIE super global variable to read the value of the cookie. For example, the following code will read the value of a cookie named "username":

$username = $_COOKIE["username"];

$username variable will contain the cookie value "John".

It should be noted that cookies can only be read throughout the application if the correct domain and path attributes are used when setting the cookie.

4. Deleting Cookies

It is also easy to delete cookies using PHP. Just set the cookie expiration time to before the current time. For example, the following code will delete the cookie named "username":

setcookie("username", "", time()-3600);

On the client side, the browser will delete the cookie named "username".

5. Summary

In web development, cookies can be used to save client data and share it between multiple requests. Setting cookies using PHP is very simple. The setcookie() function can set the cookie's name, value, expiration time, domain, path, security flag and other attributes. The value of the cookie can be read using the $_COOKIE super global variable. Set the cookie expiration time to before the current time to delete the cookie.

The above is an introduction to the PHP cookie setting function. I hope it will be helpful to everyone.

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