What are PHP cookies? How to create? How to delete it?-PHP Problem-php.cn

What are PHP cookies? How to create? How to delete it?

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Release： 2023-03-10 07:04:01

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The previous article introduced you to "Those "things" about PHP files! ! ! 》, this article continues to introduce to you what is PHP Cookie? How to create? How to delete it?

Hope it’s helpful to you!

What are PHP cookies? How to create? How to delete it?

What are Cookies?

Cookies are often used to identify users. A cookie is a small file that a server leaves on a user's computer. Each time the same computer requests a page through the browser, the cookie will be sent to the computer. With PHP, users can create and retrieve cookie values.

How to create a cookie?

setcookie() function is used to set cookies.

Note: setcookie() function must be located before the tag.

Syntax:

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

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PHPsetcookie() parameter details:

As shown in the figure:

What are PHP cookies? How to create? How to delete it?

Regarding the creation of cookies, we use code to show it specifically:

Example 1:

First create a cookie named "user" and then assign a value "PHP" and also specifies that this cookie will expire in one hour.

The code is as follows:

<?php
setcookie("user","php",time()+3600);
//在发送 cookie 时，cookie 的值会自动进行 URL 编码，在取回时进行自动解码。
//为防止 URL 编码，请使用 setrawcookie() 取而代之。
?>
方法二：用户还可以通过另一种方式设置cookie的过期时间，代码如下：
<?php
//示例1
//setcookie("user","php",time()+3600);
//在发送 cookie 时，cookie 的值会自动进行 URL 编码，在取回时进行自动解码。
//为防止 URL 编码，请使用 setrawcookie() 取而代之。
//示例2
$expire=time()+60*60*24*30;
setcookie("user", "php", $expire);
//过期时间被设置为一个月（60 秒 * 60 分 * 24 小时 * 30 天）。
?>
<html>
.....

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How to retrieve the value of Cookie?

PHP’s $_COOKIE variable is used to retrieve the value of the cookie. The code is as follows:

<?php
// 输出 cookie 值
echo $_COOKIE["user"];
// 查看所有 cookie
print_r($_COOKIE);
?>

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The running results are as follows:

What are PHP cookies? How to create? How to delete it?

Use the isset() function to confirm whether the cookie has been set:

Additional information about the usage of isset 0 function:

PHP’s isset() function - generally used to detect whether a variable is set

Format:

 boolisset( mixed var [， mixed var[，...11 )

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Function: Check whether the variable is set

Return value:

If the variable does not exist Then return FALSE
If the variable exists and its value is NULL, also return FALSE
##If the variable exists and its value If it is not NULL, TRUB will be returned. When multiple variables are checked at the same time, TRUB will be returned only when each single item meets the previous requirement. Otherwise, the result will be FALSE

The specific code is as follows:

<html>
<head>
<meta charset="utf-8">
<title>php中文网(php.cn)</title>
</head>
<body>
<?php
if (isset($_COOKIE["user"]))
echo "欢迎来到 " . $_COOKIE["user"] . "!<br>";
else
echo "普通访客!<br>";
?>
</body>
</html>

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The running results are as follows:

How to delete cookies?

What are PHP cookies? How to create? How to delete it? When deleting a cookie, you should change the expiration date to a point in time in the past.

The code is as follows:

<?php
// 设置 cookie 过期时间为过去 1 小时
setcookie("user", "", time()-3600);
?>

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What should I do if the browser does not support Cookies?

If the user's application needs to deal with a browser that does not support cookies, then the user has to use other methods to pass information between pages in the user's application. One way is to pass data through a form.
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