比较中的项目顺序[关闭]

Question

I was reading PHP's Array man and I saw this:

<?php
// fill an array with all items from a directory
$handle = opendir('.');
while (false !== ($file = readdir($handle))) {
    $files[] = $file;
}
closedir($handle); 
?>

In the readdir man page, it says "Correctly way of looping".

I'd like to know if there's a difference between X !== false and false !== X. Thanks!

Answer 1

No, there's no difference. The reason you'll sometimes see false == x instead of x == false is that it helps prevent accidentally typing x = false which is permissible in an if or loop structure but is probably not what you want. false = x is nonsensical, and will generate an error instead of silently assigning something.