Fastest way to read and write in to file in php

Fastest way to read a file or write in to a file in php is to use the functions file_get_contents and file_put_contents

To read from a file use,

$str=file_get_contents('filename');

we can even use a http url instead of a filename. To write in to a file use,

file_put_contents('writefilename', $str);