Directory operations in PHP - Mini Project: Build & Apply

Directory operations

📖 Scenario: You are managing files on a server. You want to list all files in a folder to see what is inside.

🎯 Goal: Build a PHP script that reads the contents of a directory and prints the names of all files and folders inside it.

📋 What You'll Learn

Create a variable holding the directory path

Create a variable to open the directory using opendir()

Use a while loop with readdir() to read directory entries

Print each entry name except the special entries . and ..

💡 Why This Matters

🌍 Real World

Listing files in a folder is common when managing server files, creating file browsers, or processing multiple files automatically.

💼 Career

Understanding directory operations is important for backend developers, system administrators, and anyone working with file systems in PHP.

1

Set the directory path

Create a variable called $dir and set it to the string './test_folder'.

PHP

$dir = './test_folder';
# Your code here

Hint

Use $dir = './test_folder'; to set the directory path.

2

Open the directory

Create a variable called $handle and set it to the result of opendir($dir).

PHP

<?php
$dir = './test_folder';
$handle = opendir($dir);
# Your code here

Hint

Use opendir($dir) to open the directory and assign it to $handle.

3

Read directory entries

Use a while loop with readdir($handle) assigned to $entry to read each item. Inside the loop, skip entries named . and .. using an if statement.

PHP

<?php
$dir = './test_folder';
$handle = opendir($dir);
while (($entry = readdir($handle)) !== false) {
    # Your code here
}

Hint

Use while (($entry = readdir($handle)) !== false) to loop. Use if ($entry === '.' || $entry === '..') to skip special entries.

4

Print directory entries

Inside the while loop, add a print statement to display each $entry followed by a newline. After the loop, close the directory handle with closedir($handle).

PHP

<?php
$dir = './test_folder';
$handle = opendir($dir);
while (($entry = readdir($handle)) !== false) {
    if ($entry === '.' || $entry === '..') {
        continue;
    }
    # Your code here
}
# Your code here

Hint

Use print($entry . "\n") to show each entry. Use closedir($handle) to close the directory.

Practice

1. Which PHP function is used to create a new directory?

easy

A. mkdir()

B. rmdir()

C. opendir()

D. closedir()

Solution

1. Step 1: Understand directory creation functions

   In PHP, mkdir() is the function designed to create new directories.

2. Step 2: Differentiate from other directory functions

   rmdir() removes directories, opendir() opens directories, and closedir() closes them.

3. Final Answer:

   mkdir() -> Option A

4. Quick Check:

   Create directory = mkdir() [OK]

Hint: Create folders with mkdir() function in PHP [OK]

Common Mistakes:

• Confusing mkdir() with rmdir()
• Using opendir() to create folders
• Trying to create folder without mkdir()

2. Which of the following is the correct syntax to remove an empty directory named temp in PHP?

easy

A. delete('temp');

B. remove_dir('temp');

C. rmdir('temp');

D. rm('temp');

Solution

1. Step 1: Identify the correct function for removing directories

   PHP uses rmdir() to remove empty directories.

2. Step 2: Check syntax correctness

   The syntax rmdir('temp'); correctly removes the directory named 'temp'. Other options are not valid PHP functions.

3. Final Answer:

   rmdir('temp'); -> Option C

4. Quick Check:

   Remove empty folder = rmdir() [OK]

Hint: Use rmdir('foldername') to delete empty folders [OK]

Common Mistakes:

• Using non-existent functions like remove_dir()
• Trying to delete non-empty folders with rmdir() without clearing
• Syntax errors like missing quotes or semicolons

3. What will be the output of the following PHP code?

$dir = 'myfolder';
if (is_dir($dir)) {
  $handle = opendir($dir);
  while (($file = readdir($handle)) !== false) {
    echo $file . ' ';
  }
  closedir($handle);
} else {
  echo 'Directory not found';
}

medium

A. Syntax error

B. Only files inside 'myfolder' without '.' and '..'

C. Directory not found

D. List of all files and folders inside 'myfolder' including '.' and '..'

Solution

1. Step 1: Check if directory exists

   The code uses is_dir() to check if 'myfolder' exists. If it does, it proceeds to open it.

2. Step 2: Read directory contents with readdir()

   The readdir() function reads all entries including special entries '.' (current directory) and '..' (parent directory). These are echoed with spaces.

3. Final Answer:

   List of all files and folders inside 'myfolder' including '.' and '..' -> Option D

4. Quick Check:

   readdir() lists all entries including '.' and '..' [OK]

Hint: readdir() returns '.' and '..' entries by default [OK]

Common Mistakes:

• Assuming '.' and '..' are excluded automatically
• Not checking if directory exists before reading
• Forgetting to close directory handle

4. Consider this PHP code snippet:

$dir = 'testdir';
if (mkdir($dir)) {
  echo 'Created';
} else {
  echo 'Failed';
}
rmdir($dir);

What is the main issue if the directory testdir already exists?

medium

A. mkdir() will fail and echo 'Failed', and rmdir() will fail to remove the directory

B. mkdir() will fail and echo 'Failed', but rmdir() will still remove the directory

C. mkdir() will fail and echo 'Failed', and rmdir() will remove the directory anyway

D. mkdir() will overwrite the existing directory

Solution

1. Step 1: Behavior of mkdir() when directory exists

   If testdir already exists, mkdir() returns false and echoes 'Failed'.

2. Step 2: Behavior of rmdir() on existing directory

   Since the directory exists, rmdir() will attempt to remove it. If the directory is empty and permissions allow, it will succeed. Otherwise, it will fail.

3. Final Answer:

   mkdir() will fail and echo 'Failed', but rmdir() will still remove the directory -> Option B

4. Quick Check:

   mkdir() fails if exists; rmdir() removes empty directory [OK]

Hint: mkdir() fails if folder exists; rmdir() needs empty folder [OK]

Common Mistakes:

• Assuming mkdir() overwrites existing folders
• Expecting rmdir() to always succeed
• Not checking if directory is empty before rmdir()

5. You want to list all files in a directory docs but skip the special entries . and ... Which PHP code snippet correctly does this?

hard

A. if (is_dir('docs')) {
$dh = opendir('docs');
while (($file = readdir($dh)) !== false) {
if ($file != '.' && $file != '..') {
echo $file . ' ';
}
}
closedir($dh);
}

B. if (is_dir('docs')) {
$dh = opendir('docs');
while (($file = readdir($dh))) {
echo $file . ' ';
}
closedir($dh);
}

C. foreach (scandir('docs') as $file) {
echo $file . ' ';
}

D. if (is_dir('docs')) {
$dh = opendir('docs');
while (($file = readdir($dh)) !== false) {
echo $file . ' ';
}
closedir($dh);
}

Solution

1. Step 1: Understand how to skip '.' and '..'

   The special entries '.' and '..' appear in directory listings and must be explicitly skipped.

2. Step 2: Analyze each code snippet

   if (is_dir('docs')) { $dh = opendir('docs'); while (($file = readdir($dh)) !== false) { if ($file != '.' && $file != '..') { echo $file . ' '; } } closedir($dh); } checks if the file is not '.' or '..' before echoing. foreach (scandir('docs') as $file) { echo $file . ' '; } uses scandir() but does not skip special entries.

3. Final Answer:

   The snippet using if ($file != '.' && $file != '..') -> Option A

4. Quick Check:

   Skip '.' and '..' with if check inside readdir() loop [OK]

Hint: Use if ($file != '.' && $file != '..') to skip special entries [OK]

Common Mistakes:

• Not skipping '.' and '..' entries
• Using scandir() without filtering special entries
• Forgetting to check for false in readdir() loop