Directory Traversal function

The Directory Traversal function in PHP is also very common, but it has an "object-oriented" form, so I also mention:
(1) dir, opendir
Usage:
$ D = dir ("directory name ");
$ Handle = opendir ("directory name ");
The former returns a directory object, and the latter returns a directory handle. the former returns two attributes: handle and path. The first is equivalent to the handle returned by opendir, and the second is the directory name. $ d-> handle and $ d-> path are used for access.

(2) read, readdir, rewind, rewinddir, close, closedir
The first method in each group in the three groups is the directory object method, which is called by "object-> method ()", and the last one is the function, which is called by "function name (Directory handle. read is the next file name in the returned directory. rewind is the first file name to return to the directory. close is to close the directory and stop traversing.

(3) chdir
Convert the working directory of PHP.