php：什么。 和...表示在dir-> read（）的输出中

<?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?

. 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.

. is a reference to the current directory and .. is the directory one level up.

For example, when changing up directories in linux, you would use cd .. to go up one directory.

. means current directory in linux system

.. means parent directory in linux system