PHP directory management function library compatible with PHP5_PHP tutorial

Mainly compatible with: PHP 5
1. chdir -- change directory
Syntax: bool chdir ( string directory )
Return value: integer
Function type: File access
Content description:
Change the current directory of PHP to directory. directory: the new current directory. Return value TRUE if successful, FALSE if failed.
Explanation of examples:

Program code
// current directory
echo getcwd() . "n";
chdir('public_html');
// current directory
echo getcwd() . "n";
?>


The output result is:
/home/vincent
/home /vincent/public_html

Note: "Warning: chdir(): No such file or directory (errno 2) in ***** on line *" error will appear in the loop statement.


Program code
// current directory
echo getcwd() . "n";
for($i=1; $i< =2; $i++){
chdir('whoist');
// current directory
echo getcwd() . "n";
}
?>


2. dir -- directory class
Syntax: new dir (string directory);
Return value: Class
Function type: File access
Content description:
This It is a similar object-oriented category class used to read directories. When the directory parameter directory is opened, two attributes are available: the handle attribute is like readdir(), rewinddir() and closedir() used by other non-class functions; the path attribute configures the path parameters after opening the directory. This class has three methods: read, rewind and close.
class dir {
dir ( string directory )
string path
resource handle
string read ( void )
void rewind ( void )
void close ( void )
}
Explanation of examples:

Program code
$d = dir("/etc/php5");
echo "Handle: " . $d ->handle . "n";
echo "Path: " . $d->path . "n";
while (false !== ($entry = $d->read() )) {
echo $entry."n";
}
$d->close();
?>


The output result is:
Handle: Resource id #2
Path: /etc/php5
.
..
apache
cgi
cli

Note: read method returns The order of directory entries is system dependent.
Note: This function defines the internal class Directory, which means that the user's own class cannot be defined with the same name.

3. closedir -- close directory handle
Syntax: void closedir ( resource dir_handle )
Return value: None
Function type: File access
Content description:
Closes the directory stream specified by dir_handle. The stream must have been previously opened by opendir().
Example explanation:

Program code
$dir = "/etc/php5/";
// Open a known directory, read directory into variable and then close
if (is_dir($dir)) {
if ($dh = opendir($dir)) {
$directory = readdir($dh);
closedir($dh);
}
}
?>


4. opendir -- Open directory handle
Syntax: resource opendir ( string path [, resource context] )
Return value: Integer
Function type: File access
Content description:
This function is used to open the directory data stream. The returned integer is a handle that can be operated by other directory functions closedir(), readdir() and rewinddir(). If successful, the resource of the directory handle is returned, otherwise FALSE is returned.
Example explanation:

Program code
$dir = "/etc/php5/";
// Open a known directory, and proceed to read its contents
if (is_dir($dir)) {
if ($dh = opendir($dir)) {
while (($file = readdir($dh)) !== false) {
echo "filename: $file : filetype: " . filetype($dir . $file) . "n";
}
closedir($dh);
}
}
?>


The output result is:
filename: . : filetype: dir
filename: .. : filetype: dir
filename: apache : filetype: dir
filename: cgi : filetype: dir
filename: cli : filetype: dir