How can PHP developers ensure they have a clear understanding of the values being passed to functions during file manipulation?

PHP developers can ensure they have a clear understanding of the values being passed to functions during file manipulation by using proper error handling techniques, such as checking the return values of file-related functions and using functions like `file_exists()` and `is_readable()` to verify file paths before performing operations on them. Additionally, developers can use var_dump() or print_r() to inspect the values being passed to functions for debugging purposes.

// Example code snippet demonstrating proper error handling and value checking during file manipulation

$file_path = "example.txt";

// Check if the file exists and is readable before performing operations
if (file_exists($file_path) && is_readable($file_path)) {
    // Perform file manipulation operations here
    $file_contents = file_get_contents($file_path);
    // Use var_dump() to inspect the values being passed to functions
    var_dump($file_contents);
} else {
    echo "File does not exist or is not readable.";
}