What role do quotation marks play in PHP functions like fopen() and chmod()?

Quotation marks are used in PHP functions like fopen() and chmod() to specify file paths as strings. It is important to enclose the file path in quotation marks to ensure that the function recognizes it as a string. Failure to do so may result in errors or unexpected behavior.

$file = fopen("example.txt", "r");
chmod("example.txt", 0644);