php setcookie value is null or empty string to delete cookie parsing_PHP tutorial

Many friends use setcookie to set the value to be empty or NULL. The system will automatically delete the cookie. Let me analyze the reasons why the cookie value is null or empty string to delete the cookie. Friends who need to learn can refer to it. .

This is also written in the official documentation:

#2 setcookie() delete example

The code is as follows  代码如下 复制代码 // set the expiration date to one hour ago setcookie ("TestCookie", "", time() - 3600); setcookie ("TestCookie", "", time() - 3600, "/~rasmus/", "example.com", 1); ?>

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代码如下 复制代码 $name = "post_url"; $value =  ""; setcookie($name, $value,  time()+60*60*3, "/" ); // set the expiration date to one hour ago setcookie ("TestCookie", "", time() - 3600); setcookie ("TestCookie", "", time() - 3600, "/~rasmus/", "example.com", 1); ?> I encountered a strange thing today. When setting cookie, I passed an empty string to $value, but the result turned out to be that the cookie was deleted...

The code is as follows

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$name = "post_url";

Similarly, in php, strval(NULL) === "", so setcookie($name, NULL) is equivalent to setcookie($name, ""), and this cookie can also be deleted. http://www.bkjia.com/PHPjc/632123.htmlwww.bkjia.comtruehttp: //www.bkjia.com/PHPjc/632123.htmlTechArticleMany friends use setcookie to set the value to empty or NULL. The system will automatically delete the cookie. Here I will Let me analyze the reasons for deleting cookies when the cookie value is null or empty string. If necessary...