PHP阅读目录

Question

So I'm going through reading and writing to files in PHP via PHP Docs and there's an example I didn't quite understand:

http://php.net/manual/en/function.readdir.php

if toward the end it shows an example like this:

<?php
if ($handle = opendir('.')) {
    while (false !== ($entry = readdir($handle))) {
        if ($entry != "." && $entry != "..") {
            echo "$entry
";
        }
    }
    closedir($handle);
}
?>

In what case would . or .. ever be read?

Answer 1

The readdir API call iterates over all of the directories. So assuming you loop over the current directory (denoted by ".") then you get into an endless loop. Also, iterating over the parent directory (denoted by "..") is avoided to restrict the list to the current directory and beneath.

Hope that helps.