What are common debugging techniques for PHP code, especially when dealing with issues related to file existence and directory scanning?

When debugging PHP code related to file existence and directory scanning, a common technique is to use built-in functions like file_exists() to check if a file exists before attempting to read or manipulate it. Additionally, using functions like scandir() can help in scanning directories and retrieving a list of files within them.

// Check if a file exists before reading or manipulating it
$file_path = 'path/to/file.txt';
if (file_exists($file_path)) {
    // Proceed with reading or manipulating the file
} else {
    echo 'File does not exist.';
}

// Scan a directory and retrieve a list of files
$directory_path = 'path/to/directory';
$files = scandir($directory_path);
foreach ($files as $file) {
    echo $file . '<br>';
}