php：什么。 和...表示在dir-> read（）的输出中

Question

<?php

$d = dir('css');
echo "Handle: " . $d->handle . "<br>";
echo "Path: " . $d->path . "<br>";

while (($file = $d->read()) !== false){
  echo "filename: " . $file . "<br>";
}
$d->close();
?>

Result:

Handle: Resource id #4
Path: css
filename: .
filename: ..
filename: css
filename: img
filename: index.html
filename: js
filename: lightbox

Question:

In the result, what does . and .. mean?

Answer 1

. is the current directory and .. is one up. Most code examples have if-statements to skip over em.

Here is an example out of the PHP docs:

http://php.net/manual/en/function.readdir.php#example-2318

Even on the docs, it shows the code to just ignore.