How can PHP developers ensure that file paths are correctly referenced when accessing files from subdirectories within a PHP script?

When accessing files from subdirectories within a PHP script, developers should use the `__DIR__` constant to get the absolute path of the current file and then concatenate it with the relative path to the target file. This ensures that file paths are correctly referenced regardless of the script's location within the directory structure.

// Get the absolute path of the current file
$currentDir = __DIR__;

// Define the relative path to the target file
$filePath = $currentDir . '/subdirectory/filename.txt';

// Access the file using the correct file path
$fileContent = file_get_contents($filePath);

// Display the file content
echo $fileContent;