Detailed explanation of php cookie working principle and cookie examples_PHP tutorial

In PHP, cookies are commonly used by us, but many friends may not know how cookies work. The following editor will sort out the working principle of PHP cookies and some examples of cookie reading and writing operations.

Cookies and session state

To do BS development, these two concepts are indispensable. Let’s have a general understanding first. Without practical application, it is difficult to go into depth. Please read the reference address in depth!
What are cookies?
A cookie is a small piece of text information that is passed between a web server and a browser along with user requests and pages. The information contained in the cookie can be read by the web application each time the user visits the site. Basics of How Cookies Work If a user returns to a page on the site and enters the URL www.*****.com, the browser looks for a cookie associated with that URL on their local hard drive. If the cookie exists, the browser sends it to your site with the page request.

What are cookies used for?
The most basic purpose is: Cookies can help Web sites save information about visitors. More generally, cookies are a way to maintain the continuity of a Web application (that is, to perform "state management"). It allows the Web site to remember you.

•When a customer visits a website based on PHP technology, the setcookie() function can be used in PHP to generate a cookie. After processing, the system sends the cookie to the client and saves it in the C:Documents andSettings username Cookies directory. Down.
• Cookies are part of the HTTP header, so the setcookie() function must be called before any content in the HTML itself is sent to the browser. This restriction is the same as the header() function (if you need to understand the head() function, please check it yourself).
•When the customer visits the website again, the browser will automatically send the cookie corresponding to the website in the C:DocumentsandSettings username Cookies directory to the server. The server will automatically convert the cookie passed from the client into a PHP variable. . In PHP5, cookies sent by the client will be converted into global variables. You can read it through $_COOKIE[‘xxx’].
Define a cookie
•Set cookies:
•Syntax: boolsetcookie(stringname,[stringvalue,[int expire,[stringpath,[stringdomain,[int secure]]]]]);
This cookie function can have 6 attributes, and the commonly used ones are 3 parameters.

1. Example:

The code is as follows

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代码如下	复制代码
$value="the best way is by yourself"; setcookie("cookiename",$value,time()+60*60*24*7);

$value="the best way is by yourself";

setcookie("cookiename",$value,time()+60*60*24*7);

1. Receiving and processing cookies
PHP has good support for cookies. Just like form forms, PHP will automatically receive the HTTP header from the web server and process it when received. When receiving, use $_COOKIE["cookiename"] or $HTTP_COOKIE_VARS["cookiename"] (not recommended)

1. Note:
If the website has several different file directories and uses a cookie without a path, the cookie can only be accessed in the path of the file that sets the cookie. If a path is specified, the path when setting will be used as the specified path to access the cookie.

代码如下	复制代码
setcookie("CookieArray[0]","Value1"); setcookie("CookieArray[1]","Value2");

Create cookie array:

1. One:

The code is as follows

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代码如下	复制代码
setcookie("CookieArray['one']","Value1"); setcookie("CookieArray['two']","Value2");

setcookie("CookieArray[0]","Value1"); setcookie("CookieArray[1]","Value2");

1. Second:

The code is as follows	Copy code
setcookie("CookieArray['one']","Value1"); setcookie("CookieArray['two']","Value2");

1.Use array in setcookie()

The code is as follows

代码如下	复制代码
setcookie("cookie[three]","cookiethree"); setcookie("cookie[two]","cookietwo"); setcookie("cookie[one]","cookieone"); //刷新页面后，显示出来 if(isset($_COOKIE['cookie'])){ foreach($_COOKIE['cookie']as$name=>$value){ echo"$name:$value n"; } } ?>

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setcookie("cookie[three]","cookiethree");

setcookie("cookie[two]","cookietwo");

setcookie("cookie[one]","cookieone");

代码如下	复制代码
setcookie(“MyCookie”,”Value”,time()-1);

//After refreshing the page, it will be displayed

if(isset($_COOKIE['cookie'])){

foreach($_COOKIE['cookie']as$name=>$value){

echo "$name:$value
n";

}
}

?>

Delete cookies 1. To delete an existing cookie, there are two ways:

1. Call setcookie with only the name parameter, then the cookie named this name will be deleted from the client;

setcookie("MyCookie");//Delete MyCookie 2. The expiration time is enough, then the cookie will be deleted (actually invalid) after browsing this page. For example:

The code is as follows

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setcookie("MyCookie","Value",time()-1); //Delete MyCookie. Note: When a cookie is deleted, its value is still valid on the current page. If you want to set the cookie to expire after the browser is closed. Then you can directly set expiretime to 0, or do not set this value. For example: setcookie("name","value",0). Cookie Notes •1. There cannot be any html output before setcookie(), even spaces and blank lines will not work. It must be set before the content of the html file is output •2. After setcookie(), there will be no output when you call echo$_COOKIE["name"] on the current page. You must refresh or go to the next page to see the cookie value. •3. No need for browsers to handle cookies differently. The client can disable cookies, and the browser will also limit the number of cookies. The maximum number of cookies that can be created by a browser is 300, and each cookie cannot exceed 4KB. The total number of cookies that can be set by each WEB site cannot exceed 20. •4. Cookies are stored on the client side. If the user disables cookies, your cookies will naturally have no effect! Therefore, avoid over-reliance on cookies and think about solutions if cookies are disabled, just in case. http://www.bkjia.com/PHPjc/633059.htmlwww.bkjia.comtruehttp: //www.bkjia.com/PHPjc/633059.htmlTechArticleIn php, cookies are commonly used by us, but many friends may not know how cookies work. Below The editor will sort out for you the working principle of php cookies and some...