这个PHP $ _COOKIE代码片段出了什么问题？

Question

I have an input='text' name='fileName' element and want to store its value in the cookie filename. When first created, cookie filename is assigned default constant DEFAULT_FILE_NAME If the request variable fileName is set (thru POST method), then cookie filename is assigned the value of this request variable. Otherwise, the cookie retains its old value. . I try to do it using the following snippet:

    if (!isset($_COOKIE['filename'])) {
        setcookie('filename', DEFAULT_FILE_NAME);
        $_COOKIE['filename'] = DEFAULT_FILE_NAME;
    } 
    if (isset($_REQUEST['fileName'])) {
        setcookie('filename', $_REQUEST['fileName']);
        $_COOKIE['filename'] = $_REQUEST['fileName'];
    } 

The problem is that when the request variable fileName is not set, the cookie is recognized as non-existent, and is assigned DEFAULT_FILE_NAME again. What goes wrong?

---

I have one form and three submit buttons on it which serve as main menu. If Submit #1 is clicked then I draw the UI for specifying file name ('fileName' element). User enters file name and clicks OK and after that it is assigned to the cookie 'filename' because file name is used throughout the app. (Of course, when user clicks Submit #1 and the cookie 'filename' is already set, I write its value to the 'fileName' element.). While I am within the UI created by the Submit #1 and 'fileName' elem is visible, everything is OK and the cookie is set/read successfully. But when I click submit #2 which draws UI for another needs, but uses the cookie 'filename', that's when the problem arises. I find that the cookie 'filename' loses its value read from the 'fileName' element and is assigned default value again.

Answer 1

PHP.net:

Once the cookies have been set, they can be accessed on the next page load with the $_COOKIE or $HTTP_COOKIE_VARS arrays. Note, superglobals such as $_COOKIE became available in PHP 4.1.0. Cookie values also exist in $_REQUEST.

Try this:

if (!isset($_COOKIE['filename'])) {setcookie('filename')}

if (isset($_REQUEST['fileName'])) {
    setcookie('filename', $_REQUEST['fileName']);
}
else{
     setcookie('filename', DEFAULT_FILE_NAME);
}

UPDATE: Maybe this:

if (!isset($_COOKIE['filename'])) {setcookie('filename'),DEFAULT_FILE_NAME,time()+3600);}

if (isset($_REQUEST['fileName'])) {setcookie('filename', $_REQUEST['fileName'],time()+3600);}