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php setcookie时值为null或空字符串(删除cookie)

程序员文章站 2024-02-18 08:13:10
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在php中设置cookie与删除cookie都可以使用php setcookie来实现,如果设置就设置有值,如果删除就设置 cookie value为空或null或时间过期都可以删除,下面我们来看一些实例。

长久以来,在php中删除cookie的时候,都是使用
bool setcookie ( string $name [, string $value [, int $expire = 0 [, string $path [, string

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

$value 随便写, $expire设置为一个已经过去的时间即可。

官方文档中也是这样写的:

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:

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);
?>

今天遇到一件奇怪的事, 在setcookie的时候,传了一个空字符串给$value,结果竟然是此cookie被删除了

代码如下 复制代码

$name = "post_url";
$value = "";
setcookie($name, $value, time()+60*60*3, "/" );

delete_cookie

相当不解。

去翻php 5.4.13 的源码:

ext/standard/head.c

代码如下 复制代码

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 '=,;

\t\r\n\013\014'" );
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 ',;

\t\r\n\013\014'" );
91 return FAILURE;
92 }
93
94 len += name_len;
95 if (value && url_encode) {
96 int encoded_value_len;
97
98 encoded_value = php_url_encode(value, value_len, &encoded_value_len);
99 len += encoded_value_len;
100 } else if ( value ) {
101 encoded_value = estrdup(value);
102 len += value_len;
103 }
104 if (path) {
105 len += path_len;
106 }
107 if (domain) {
108 len += domain_len;
109 }
110
111 cookie = emalloc(len + 100);
112
113 if (value && value_len == 0) {
114 /*
115 * MSIE doesn't delete a cookie when you set it to a null value
116 * so in order to force cookies to be deleted, even on MSIE, we
117 * pick an expiry date in the past
118 */
119 dt = php_format_date("D, d-M-Y H:i:s T", sizeof("D, d-M-Y H:i:s T")-1, 1, 0

TSRMLS_CC);
120 snprintf(cookie, len + 100, "Set-Cookie: %s=deleted; expires=%s", name, dt);
121 efree(dt);
122 } else {
123 snprintf(cookie, len + 100, "Set-Cookie: %s=%s", name, value ? encoded_value :

"");
124 if (expires > 0) {
125 const char *p;
126 strlcat(cookie, "; expires=", len + 100);
127 dt = php_format_date("D, d-M-Y H:i:s T", sizeof("D, d-M-Y H:i:s T")-1,

expires, 0 TSRMLS_CC);
128 /* check to make sure that the year does not exceed 4 digits in length */
129 p = zend_memrchr(dt, '-', strlen(dt));
130 if (!p || *(p + 5) != ' ') {

参数中的value在C语言中的类型是char * , 还有一个 value_len标明了它的长度。
如果value_len为0的话,就写了下面的cookie:
值为”deleted”, 过期时间为 Thu, 01-Jan-1970 08:00:01 CST 或者说是 Thu, 01-Jan-1970 00:00:01

GMT

看来setcookie($name, “”) 确实可以删除这个cookie了…
同理,在php中,strval(NULL) === “” , 所以 setcookie($name, NULL) 也就相当于 setcookie($name,

“”),同样可以删除此cookie.

另外,比较好奇的是:

代码如下 复制代码
if (value && value_len == 0) {
}
else {
}

else 中包含了 value 为null 的情况, 这是一种什么样的情况呢?

看来setcookie($name, “”) 确实可以删除这个cookie了…
同理,在php中,strval(NULL) === “” , 所以 setcookie($name, NULL) 也就相当于 setcookie($name,

“”),同样可以删除此cookie.

另外,比较好奇的是:

代码如下 复制代码
if (value && value_len == 0) {
}
else {
}

else 中包含了 value 为null 的情况, 这是一种什么样的情况呢?