Detailed introduction to how php uses cookies

This article mainly introduces the use of Cookies in PHP: adding (setcookie), reading ($_COOKIE) and deleting (setcookie), which has a good reference value. Let’s take a look with the editor below.

What is a cookie

The server saves the user's information on the client, such as login name, password, etc. These data are like cookies. The amount of data is not large. The server can read it from the client when needed and save it in the client's browser cache directory

① When the browser accesses the cookie. php, the server will send an http response. When the browser obtains the message, it will save the cookie information to the local disk

② If we do not have time (the third parameter), the cookie will not be saved To the client, when the browser session ends, the cookie will expire

③ The cookie saves string information

④ The client can save multiplekey=>val

⑤ During the cookie saving process, Chinese characters will be urlencode encoded. Cookies can have multiple key=>val, and different validity times can be set for different key values.

Let’s take a look at the specific usage of cookies:

The setcookie() function sets cookies to the client computer

Note: The setcookie() function must be located before the tag. When sending a cookie, the value of the cookie will be automatically URL encoded and automatically decoded when retrieved.

$_COOKIERead the contents of the cookie on the server side

uniqid()The function is based on The current time in microseconds, generating a unique ID.

Note: Because it is based on system time, the ID generated by this function is not optimal. If you need to generate an absolutely unique ID, please use the md5() function

<?php
header(&#39;Content-type:text/html;charset=utf-8&#39;);

//setcookie()函数，添加cookie
var_dump(setcookie(&#39;name&#39;,&#39;cmcc&#39;,time()+3600));
echo &#39;<br />&#39;;

// $_COOKIE函数，读取cookie
var_dump($_COOKIE);
echo &#39;<br />&#39;;

// uniqid()函数，生成一个唯一的ID
$id=uniqid(rand(1000,9999).&#39;_&#39;);
var_dump(setcookie(&#39;id&#39;,$id,time()+3600));

// setcookie()函数，删除cookie
var_dump(setcookie(&#39;id&#39;,&#39;&#39;,time()-3600));
?>

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