PHP cookie study notes_PHP tutorial-PHP Tutorial-php.cn

PHP cookie study notes_PHP tutorial

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Release： 2016-07-13 17:15:36

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Cookie is a session that is used in all programs. Below I will share my notes on learning php cookies with my classmates. This article introduces all the tips about getting started with cookies. Students in need can refer to it.

What does Cookie mean?

Cookies are used to store usernames, passwords, number of visits to the site, etc. When visiting a website, the cookie sends a small piece of information from the html web page to the browser, which is saved on the client's computer in the form of a script.

What are cookies used for? If a server is used to record the number of times a user logs onto the site, the data accumulated over a long period of time must be very large, which is a heavy burden on the server. Therefore, the data can be stored in the user's own computer, and when needed, the server will read the cookie on the user's computer to extract the data, so that the server does not need to record a large amount of data.

Generally speaking, cookies are returned from the server to the browser through HTTP Headers. First, the server uses Set Cookie Header in the response to create a Cookie. The browser then includes the created cookie in the request through the Cookie Header and returns it to the server to complete the browser verification.

Creation of Cookie

php needs to call the setcookie() function to create a cookie, and its structure is as follows:

bool setcookie(string name[,string value[,int expiration[,string path[,bool secure]]]])
The parameter name represents the name of the cookie, other parameters are optional;
The parameter value is the value stored in the cookie;
The parameter expiration specifies the time when the cookie expires;
The parameter path specifies the effective path of the cookie on the server, which is used to set the folder where the cookie will be sent to the server;
The secure parameter specifies whether the cookie is sent over a secure https link.
php cookie example code:

The code is as follows

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代码如下	复制代码
setcookie("c1","my name is Rose",time()+3600); /* 建立一个名称为"c1"的cookie 过期时间为3600秒 */ ?>

setcookie("c1","my name is Rose",time()+3600); /* Create a cookie named "c1" with an expiration time of 3600 seconds */ ?>

Cookie access

Most variables only occupy space in memory, so the variables are also released from memory when the php script terminates. Cookies can store the value of a variable on the hard drive of the user's computer for a long time. When we need to call the value of this variable, just read the name of the cookie.

代码如下	复制代码
echo "c1的Cookie值是 " .$_COOKIE['c1'] ." "; echo "c2的Cookie值是 " .$_COOKIE['c2']; ?>

Cookie creation in the previous section has created a cookie named "c1". Let's test whether this cookie is successfully created. Instance of php accessing cookies:

The code is as follows	Copy code
echo "The cookie value of c1 is " .$_COOKIE['c1'] ." "; echo "The cookie value of c2 is " .$_COOKIE['c2']; ?>

Cookie time

If the validity time of the cookie is not set, the cookie will disappear when the browser is closed. If you want to retain the cookie, you must set a valid time for it.

php Cookie time setting method:

time()+seconds
time() represents the time of the current user's operating system, and the following seconds are the validity time of the cookie. If you want to specify a specific date, you can use the mktime() function, whose structure is as follows:

mktime (hour, minute, second, month, day, year)
If you want to delete a cookie immediately, you can set the time to a time in the past.

php Cookie time setting example:

The code is as follows

代码如下	复制代码
setcookie("a","10",time()-60); /* 设置时间为之前60秒，其值立即被删 / setcookie("a","10",time()+60); / 设置有效时间为60秒 / setcookie("a","10",mktime(0,0,0,11,1,2011)); / 失效时间为2011年11月1日0点0分0秒 */

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setcookie("a","10", time()-60); /* Set the time to the previous 60 seconds, and its value will be deleted immediately*/

代码如下	复制代码
$count=$_COOKIE['user']; $count++; setcookie("user",$count,time()+3600); echo "这是你的第 $count 次访问!"; ?>

setcookie("a","10",time()+60); /* Set the valid time to 60 seconds */

setcookie("a","10",mktime(0,0,0,11,1,2011)); /* The expiration time is 0:00:00 on November 1, 2011 */

The following introduces a simple statistical program designed using cookies:

We can also create a php cookie array. The implementation method is introduced below through examples.

The code is as follows

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代码如下	复制代码
setcookie('name[1]','Rose'); setcookie('name[2]','John'); setcookie('name[3]','Mikle'); if(is_array($_COOKIE['name'])){ /* 判断是否数组 */ foreach($_COOKIE['name'] as $name=>$value) { echo "$name:$value "; } } else echo "不是数组"; ?>

$count=$_COOKIE['user']; $count++;

setcookie("user",$count,time()+3600);

echo "This is your $count visit!";

Cookie Array

Code:

The code is as follows

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setcookie('name[1]','Rose');<🎜> setcookie('name[2]','John');<🎜> setcookie('name[3]','Mikle');<🎜> if(is_array($_COOKIE['name'])){ /* Determine whether it is an array */<🎜> foreach($_COOKIE['name'] as $name=>$value) { echo "$name:$value
"; } } else echo "Not an array"; ?> Cookie restrictions Cookies are used to store important information when users browse websites. In order to prevent misuse and leakage of user information, certain restrictions are placed on Cookies: The browser records that the user cookie size is limited to 4KB; The browser only saves the number of cookies of a certain site server, which is limited to 20. If this number is exceeded, the previously saved cookies will be deleted. Each user's browser can only access a maximum of 300 cookies. Users can set whether to enable cookies to store information in their browser settings. Therefore, to use cookies to store information, you must first confirm whether the cookie function in the browser is turned on. For example, in IE9 browser, open "Properties" - "Privacy" - "Advanced" options and select Enable: Tip: After the browser creates a cookie, every request for the website will carry this cookie in the header. And the browser will always send it to know where the cookie expires. However, for requests from other websites, cookies will never be sent.