Exploring Folders

Php-mysql Course

PHP has functions that can also open directories (folders) and explore their contents, or create new folders.

Creating folders with PHP

To create a folder with PHP, use the mkdir() function. Returns TRUE on success or FALSE on failure.
  - Syntax:

mkdir('pathname ', mode)

- "pathname " is the path and name of the new directory.
- "mode" sets the CHMOD permissions. It is optional (0777 by defaul).
  - Example:

<?php
if (mkdir('files/newdir', 0755)) echo 'The "newdir" was created';
else 'Unable to create "newdir"';
?>

This code attempt to create a folder named "newdir" in the "files" directory, with 0755 CHMOD permissions, and output a message on success or failure.
• PHP must have write permissions in the "files" directory.

Reading a directory content

You can read the content of a directory with one of the fallowing functions:

• scandir('dir_path') - Returns an array of files and directories inside the "dir_path" (sorted in alphabetical ascending order), or FALSE on failure.
• readdir($dir_handle) - Returns the filename of the next file from the folder, or False. The filenames are returned in the order in which they are stored by the filesystem.
  - "$dir_handle" is a handle resource opened with opendir()

  - Example:

<?php
$dir = './files';

// read the dir-content with scandir()
$ar_dir = scandir($dir);
var_export($ar_dir);

echo '<h5>Using readdir()</h5>';

// read the dir-content with readdir()
if ($dc = @opendir($dir)) {
  while($ok = readdir($dc)) {
    echo '<br />'. $ok;
  }
  closedir($dc);
}
else echo 'Unable to open the directory';
?>

"./" indicates the root directory of the Web site (www or htdocs). So, the "files" folder is located in the Web site root folder.
"opendir()" opens a directory and return a reference to it; "closedir()" closes an opened folder (similar with "fopen()" and "fclose()" for files).
The above code will output something similar to:
• Another way to Inspect the contents of a folder is with the DirectoryIterator class.
It returns an SplFileInfo object that gives you access to a lot more information about the folder's contents. See the official reference: The DirectoryIterator class

Get information about a file path

An useful PHP function to get info about a file path is pathinfo(). It returns an associative Array with the fallowing elements (keys):

• dirname - parent directory's path. The same as dirname() function
• basename - the base name of the given path. The same as basename() function
• extension (if any) - the extension of the base name (if exists)
• filename - the name of file, without extension

  - Example:

<?php
$path = 'files/php-mysql/file_system.php';
$ar_path = pathinfo($path);
var_export($ar_path);

echo '<hr />';

// or, using directly dirname() and basename() function
echo '<br /> dirname() returns - '. dirname($path);
echo '<br /> basename() returns - '. basename($path);
?>

This code will output:

Other useful functions for file (folder) system

• getcwd() - Gets the current working directory
• parse_url($url) - parses a URL and returns an associative array containing the fallowing items (keys), with components of the URL:
  • "scheme" (e.g. http), "host", "port", "user", "pass", "path", "query" (after the question mark ?), "fragment" (after the hashmark #)
  - Example:

  <?php
  $url = 'https://coursesweb.net/php-mysql/index.php?id=89#mp';
  $ar_parse_url = parse_url($url);
  var_export($ar_parse_url);
  
  /* Output:
   array ( 'scheme' => 'http', 'host' => 'coursesweb.net', 'path' => '/php-mysql/index.php', 'query' => 'id=89', 'fragment' => 'mp', )
  */
  ?>
  

• disk_free_space($dir) - returns the free space, in bytes, of the specified directory
• is_dir('dir') - returns TRUE if the "dir" exists
• is_file('file') - returns TRUE if "file" is a regular file
• is_readable('filename') - returns TRUE if the file or directory specified by "filename" exists and is readable
• is_writable('filename') - returns TRUE if the file or directory specified by "filename" exists and is writable

<a href="http://coursesweb.net/" title="CoursesWeb.net">CoursesWeb.net</a>

h2 {
  font-family:"Calibri",sans-serif;
}

var elm_list = document.querySelectorAll("div.cls");
var nr_elms = elm_list.length;       // number of selected items
alert(nr_elms);

$arr =[1, 2, 3, 4);
$arr_sum = array_sum($arr);
echo $arr_sum;       // 10