php - 只有变量应该通过引用传递

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'
);

有什么想法吗？ 2天后仍然卡住。

Answer 1

将 explode 的结果赋值给一个变量，并将该变量传递给 end:

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

问题是，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) .

explode('.', $file_name) 的结果不能转为引用。这是 PHP 语言中的一个限制，可能出于简单原因而存在。