How can PHP developers ensure that their code is secure and efficient when working with file paths and variables?

To ensure that PHP code is secure and efficient when working with file paths and variables, developers should sanitize user input to prevent against directory traversal attacks and other vulnerabilities. They should also validate file paths and use secure file handling functions to prevent security risks. Additionally, developers should properly handle errors and exceptions to maintain code efficiency and reliability.

// Sanitize user input to prevent directory traversal attacks
$filename = basename($_GET['file']);

// Validate file path and use secure file handling functions
if (file_exists('/path/to/files/' . $filename)) {
    $file_contents = file_get_contents('/path/to/files/' . $filename);
    // Process file contents
} else {
    echo 'File not found';
}

// Properly handle errors and exceptions
try {
    // Code block that may throw exceptions
} catch (Exception $e) {
    // Handle exceptions
}