When php setcookie the value is null or empty string (delete cookie)_PHP tutorial

Setting cookies and deleting cookies in php can be achieved using php setcookie. If it is set, it will be set with a value. If it is deleted, it will be set. The cookie value can be deleted if it is empty or null or the time has expired. Let's look at some examples below.

For a long time, when deleting cookies in php, you have used
bool setcookie ( string $name [, string $value [, int $expire = 0 [, string $path [, string

$domain [, bool $secure = false [, bool $httponly = false ]]]]]] )

Write $value as you like, and set $expire to a time that has passed.

This is also written in the official documentation:

http://www.php.net/manual/en/function.setcookie.php

Example #2 setcookie() delete example
When deleting a cookie you should assure that the expiration date is in the past, to trigger

the removal mechanism in your browser. Examples follow how to delete cookies sent in previous

example:

The code is as follows	Copy code
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); ?>

// 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

代码如下	复制代码
$name = "post_url"; $value =  ""; setcookie($name, $value,  time()+60*60*3, "/" ); delete_cookie

…

The code is as follows	Copy code
$name = "post_url"; $value = ""; setcookie($name, $value, time()+60*60*3, "/" ); delete_cookie

Quite puzzled.

Go to the source code of php 5.4.13:

ext/standard/head.c

The code is as follows

Copy code

173 PHP_FUNCTION(setcookie) 174 { 175 char *name, *value = NULL, *path = NULL, *domain = NULL; 176 long expires = 0; 177 zend_bool secure = 0, httponly = 0; 178 int name_len, value_len = 0, path_len = 0, domain_len = 0; 179 180 if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "s|slssbb", &name, 181 &name_len, &value, &value_len, &expires, &path, 182                                                                      &path_len, &domain, &domain_len, &secure, &httponly) == FAILURE) { 183 return; 184 } 185 186 If (php_setcookie(name, name_len, value, value_len, expires, path, path_len, domain, domain_len, secure, 1, httponly TSRMLS_CC) == SUCCESS) { 187 RETVAL_TRUE; 188 } else { 189 RETVAL_FALSE; 190 }   191 }   76 PHPAPI int php_setcookie(char *name, int name_len, char *value, int value_len, time_t expires, char *path, int path_len, char *domain, int domain_len, int secure, int url_encode, int httponly TSRMLS_DC) 77 { 78 char *cookie, *encoded_value = NULL; 79 int len=sizeof("Set-Cookie: "); 80 char *dt; 81 sapi_header_line ctr = {0}; 82 int result; 83 84 if (name && strpbrk(name, "=,; trn1314") != NULL) { /* man isspace for 13 and 14 */ 85        zend_error( E_WARNING, "Cookie names cannot contain any of the following '=,; trn 86 return FAILURE; 87 } 88 89     if (!url_encode && value && strpbrk(value, ",; trn1314") != NULL) { /* man isspace for 13 and 14 */ 90        zend_error( E_WARNING, "Cookie values ​​cannot contain any of the following ',; trn