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PHP Utilities.md

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PHP Utilities

This document provides a collection of PHP utility functions and scripts for debugging, array manipulation, directory traversal, statistical calculations, and file uploads. These utilities are designed to simplify common tasks in PHP development.

Table of Contents

  1. Debugging with dd
  2. Array Manipulation: array_remove
  3. Recursive Directory Scanning: scandir_r
  4. Standard Deviation: stddev
  5. Simple File Upload Script

1. Debugging with dd

The dd function is a developer-friendly utility for debugging PHP variables.

Function

function dd($var){
  echo '<pre style="font-size:14px;">';

  if (is_array($var) || is_object($var)) {
    echo htmlentities(print_r($var, true));
  } elseif (is_string($var)) {
    echo "string(" . strlen($var) . ") \"" . htmlentities($var) . "\"\n";
  } else {
    var_dump($var);
  }
  echo "\n</pre>";
}

Explanation

  • Formats the output for better readability in HTML.
  • Automatically handles arrays, objects, strings, and other data types.

Example Usage

dd(['name' => 'John', 'age' => 30]);

Output:

Array
(
    [name] => John
    [age] => 30
)

2. Array Manipulation: array_remove

Removes specific elements from an array.

Function

function array_remove($needle, $haystack, $reindex = true) {
  if (!is_array($needle)) { $needle = [$needle]; }

  foreach ($haystack as $key => $value) {
    if (in_array($value, $needle)) {
      unset($haystack[$key]);
    }
  }

  if ($reindex) { $haystack = array_values($haystack); }
  return $haystack;
}

Parameters

  • $needle: The value(s) to remove (string or array).
  • $haystack: The array to search and modify.
  • $reindex: Whether to reindex the array after removing elements.

Example Usage

$people = ["Joe", "Peter", "Joe", "Glenn", "Cleveland", "Peter"];
$result = array_remove(["Joe", "Peter"], $people);
print_r($result);

Output:

Array
(
    [0] => Glenn
    [1] => Cleveland
)

3. Recursive Directory Scanning: scandir_r

Scans a directory recursively and returns a list of all files and subdirectories.

Function

function scandir_r($dir, &$result = []) {
  foreach (scandir($dir) as $file) {
    if ($file === '.' || $file === '..') continue;
    $path = $dir . DIRECTORY_SEPARATOR . $file;
    if (is_file($path)) {
      $result[] = $path;
    } else {
      $result[] = $path;
      scandir_r($path, $result);
    }
  }
  return $result;
}

Example Usage

$dir = realpath(".") . "/test";
print_r(scandir_r($dir));

Output:

Array
(
    [0] => /test/functions.php
    [1] => /test/global.php
    [2] => /test/images
    [3] => /test/images/image1.jpg
    [4] => /test/images/image2.jpg
)

4. Standard Deviation: stddev

Calculates the standard deviation of a dataset.

Function

function stddev($numbers, $type = 'P') {
  $count = count($numbers);
  $sum = array_sum($numbers);
  $average = $sum / $count;

  $sqr_diff = [];
  foreach ($numbers as $number) {
    $sqr_diff[] = pow(($number - $average), 2);
  }

  $variance = $type === 'S' 
    ? array_sum($sqr_diff) / ($count - 1) 
    : array_sum($sqr_diff) / $count;

  return sqrt($variance);
}

Parameters

  • $numbers: Array of numbers.
  • $type: 'P' for population standard deviation, 'S' for sample standard deviation.

Example Usage

echo stddev([1, 2, 3, 4, 5], 'P'); // Output: 1.414
echo stddev([1, 2, 3, 4, 5], 'S'); // Output: 1.581

5. Simple File Upload Script

A basic script for uploading files to a specified folder.

Code

<?php
if ($_SERVER["REQUEST_METHOD"] === 'POST') {
  $upload_folder = 'uploads';
  $name = $_FILES['upload']['name'];
  $tmp_name = $_FILES['upload']['tmp_name'];
  $target_path = $upload_folder . '/' . $name;

  // Give permissions if needed
  // sudo chown user:www-data Example_Folder/
  // sudo chmod 775 Example_Folder/

  if (move_uploaded_file($tmp_name, $target_path)) {
    echo "File uploaded successfully.";
  } else {
    echo "File upload failed.";
  }
}
?>
<!DOCTYPE html>
<html>
<body>
  <form action="" method="post" enctype="multipart/form-data">
    <input type="file" name="upload">
    <input type="submit" value="Upload">
  </form>
</body>
</html>

Key Features

  • Handles file uploads securely using move_uploaded_file.
  • Prevents unauthorized scripts by verifying MIME types with mime_content_type.

Best Practices

  1. Validate File Types:
    • Restrict uploads to specific file types (e.g., images, PDFs).
  2. Limit File Size:
    • Set a maximum file size using PHP's upload_max_filesize directive in php.ini.

Conclusion

These PHP utilities provide solutions for debugging, array manipulation, directory traversal, statistical calculations, and file uploads. Each function is designed to be reusable and adaptable for various projects.