仅变量应通过引用传递

Question

// Other variables
$MAX_FILENAME_LENGTH = 260;
$file_name = $_FILES[$upload_name]['name'];
//echo "testing-".$file_name."<br>";
//$file_name = strtolower($file_name);
$file_extension = end(explode('.', $file_name)); //ERROR ON THIS LINE
$uploadErrors = array(
    0=>'There is no error, the file uploaded with success',
    1=>'The uploaded file exceeds the upload max filesize allowed.',
    2=>'The uploaded file exceeds the MAX_FILE_SIZE directive that was specified in the HTML form',
    3=>'The uploaded file was only partially uploaded',
    4=>'No file was uploaded',
    6=>'Missing a temporary folder'
);

有任何想法吗？2天后仍然卡住。

Answer 1

将的结果分配explode给变量，然后将该变量传递给end：

$tmp = explode('.', $file_name);
$file_extension = end($tmp);

问题是，这end需要引用，因为它修改了数组的内部表示（即，它使 当前元素指针 指向最后一个元素）。

的结果explode('.', $file_name)不能转换为参考。这是PHP语言的一种限制，出于简化的原因可能存在。