How to create, read and delete cookies in PHP?

In the previous article, I brought you "Five minutes to help you understand the magic methods in PHP (detailed examples)", which introduced you in detail to the magic methods commonly used in PHP. This article In this article, let’s take a look at the relevant knowledge of cookies in PHP. I hope it will be helpful to everyone!

In our daily life, when you log in to a website, there will be information left when you last logged in when you were interrupted, and you will also see you on different pages in the shopping cart. The products you see are a means used by the website to identify users, in order to push content to users conveniently. If you want to implement such complex functions, you need to use cookies, so let's take a look at what cookies are. What are its uses and how to create, read and delete it.

What isCookie

Many functions can be achieved through cookies, so what are cookies? Cookies are a way to save a small amount of data passed by the server to the browser under the HTTP protocol in the user's browser. For example, it can save some user information, so that even if the browser is closed or the connection is interrupted, the user can still maintain this data.

It can also be understood that a cookie saves the specific information of the browser webpage in the form of a file on the client's hard drive. When you visit this website again, the browser will first read the cookie file. , the read data is provided to the browser. In this way, it is achieved that the user's webpage has some personalized settings, which will be saved when opened again. This is how they are displayed via cookies.

CookieThe main uses of

The uses of cookies are There are many kinds of information in cookies. The server can use the arbitrariness of the information contained in cookies to filter the information and maintain the information. The purpose of this is to determine the status of HTTP transmission. The most typical application of cookies is also very common in our daily life, which is to determine whether a registered user has logged in to the website, and there are functions similar to the shopping cart in the mall.

Let me summarize that cookies are commonly used in the following three aspects:

• Record some information of users; similar to the user personalization mentioned above set up.

• Transfer data between pages; that is, when the data of one page is to be used on another page.

• Store the viewed Web pages in temporary cookie files to speed up web page access.

What we need to note is that it is generally not recommended to use cookies to save data sets or larger data. At the same time, not all browsers support cookies, and the data information is It is saved in the form of text. In order not to affect the security of the website, it is best not to save sensitive unencrypted data.

Create cookie

If you create a cookie in PHP, you need thesetcookie()function to create the cookie. What we need to note is that cookies are part of the HTTP response header, and the response header must be output first. If an HTML, blank line, echo, etc. is output before the setcookie() function, it may cause a program error.

setcookie()The syntax format of the function is as follows:

setcookie(string $name [, string $value = "" [, int $expire = 0 [, string $path = "" [, string $domain = "" [, bool $secure = false [, bool $httponly = false ]]]]]])

What we need to pay attention to is:

• $name---Indicates the name of the cookie;

• $value---is an optional parameter that can be used to set the cookie. The value;

• $expire--- is an optional parameter used to set the expiration time of the cookie. This time is in the form of a Unix timestamp. Some cookies are temporary and some are persistent. Temporary cookies will exist on the browser for a certain period of time. Once the specified time expires, the cookie will be cleared by the system.

• $path---Optional parameter, used to set the valid server path of the cookie.

• $domain---Optional parameter used to set the effective domain name/subdomain name of the cookie.

• $secure---Optional parameter, used to set whether this cookie is only passed to the client through a secure HTTPS connection.

Let’s take a look at creating a cookie through an example:

'; print_r($_COOKIE); ?>

Output result:

In What we need to pay attention to when running is: when running this script file for the first time, there will be no output information, so after setting the cookie, you need to refresh the page, so that the HTTP header will carry the last setting on the next request. Cookie information, then the cookie can be read.

Read cookie

在PHP中，想要读取cookie就需要使用超级全局变量$_COOKIE，$_COOKIE是一个储存着所有信息的数组，它的语法格式如下：

$_COOKIE['Cookie 名称']

实例如下：

'; print_r($_COOKIE); echo 'Website 的值为：'.$_COOKIE['Website'].'
'; echo 'Title 的值为：'.$_COOKIE['Title']; ?>

输出结果：

由此我们边通过$_COOKIE 读取到了cookie的值。

删除cookie

我们在上文中说，可以给临时的cookie设置一个时间，当时间过了之后，系统会自动删除这个cookie，那能不能够当 Cookie 被创建后，没有设置它的失效时间，其 Cookie 文件会在关闭浏览器时被自动删除。如果要在关闭浏览器之前删除 Cookie 文件，同样需要使用setcookie()函数。

删除 Cookie 和创建 Cookie 的方式基本类似，只需要使用 setcookie() 函数将 Cookie 的值（也就是第二个参数）设置为空，或者将 Cookie 的过期时间（也就是第三个参数）设置为小于系统的当前时间即可。

实例如下：

'; print_r($_COOKIE); ?>

输出结果：

如此我们便完成了删除cookie的值。

大家如果感兴趣的话，可以点击《PHP视频教程》进行更多关于PHP知识的学习。

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