PHP Delete Cookie effective method, PHP delete cookie_php tutorial

PHP Delete Cookie effective method, PHP Delete cookie

PHP effective way to delete cookies
Instructions for deleting a cookie start-----

BOOL Setcookie (string name [, string value [, int expire [, String path [, string domain [, bool secure]]])

To delete a cookie, you need to ensure that its expiration period is in the past before it triggers the browser's removal mechanism.

The following example shows how to delete a cookie that you just set:
Set the expiration time to one hour ago
Setcookie ("TestCookie", "", Time ()-3600);
Setcookie ("TestCookie", "", Time ()-3600, "/~rasmus/", ". utoronto.ca", 1);
?>

-----The end of the instructions for deleting cookies-----

The way to delete a cookie is to set the cookie's validity period to the current time, which is what almost any PHP programmer would do.

Later, a friend of my first contact with PHP told me that in the program he had wanted to set the value of a cookie to null, resulting in the cookie being deleted directly. My first reaction was not to believe, so the test
A moment:
Setcookie ("TestCookie", "');
Print_r ($_cookie);

The result is that the entire $_cookie array is empty, not just $_cookie[' TestCookie '). So with Winsock grab packet, observe the return HTTP header, found HTTP header unexpectedly is "set-cookie:testcookie=deleted;" Expires=mon, 18-jun-2007 02:42:33 GMT ", which shows" Setcookie ("TestCookie", "');" It is true that TestCookie is deleted directly from the cookie, which is completely not explained in the PHP manual.

Finally read the PHP source code, finally found the truth (this is the benefits of open source, what is unclear inside, directly check the source).

The following code can be found in the php5.20 Linux source package near line 99th EXT/STANDARD/HEAD.C:
if (value && Value_len = = 0) {
/*
* MSIE doesn ' t delete a cookie when you set it to a null value
* So-in order-to-force cookie to is deleted, even on MSIE, we
* Pick an expiry date 1 and 1 second in the past
*/
time_t t = time (NULL)-31536001;
DT = Php_format_date ("D, d-m-y h:i:s T", sizeof ("D, d-m-y h:i:s T")-1, T, 0 tsrmls_cc);
sprintf (Cookie, "Set-cookie:%s=deleted; expires=%s ", name, DT);
Efree (DT);
} else {
sprintf (Cookie, "Set-cookie:%s=%s", Name, value encoded_value: "");
if (Expires > 0) {
strcat (Cookie, "; Expires= ");
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);
strcat (cookie, DT);
Efree (DT);
}
}

The source code clearly shows "if (value && Value_len = = 0)", when "Value_len" is 0 o'clock, "sprintf (Cookie," Set-cookie:%s=deleted; expires=%s ", name, DT);" The HTTP header that deletes the cookie is sent to the browser.

Finally, we can conclude that "Setcookie ($cookiename,") is used in PHP; or "Setcookie ($cookiename, NULL);" Will delete cookies, of course, not in these manuals.

Source: http://www.111cn.net/phper/21/f0eace11b1229a0f2c7c54e3c1ea4654.htm

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