$foo = 'charanjeet/working/with/php';
echo strrpos($foo, '/', -5);
echo (bool)strrpos($foo, '/', -5);
//Answer: 18 => It will start searching it reverse direction after ignoring 5 five characters.
//It will then return the position of the / after working, from the beginning charanjeet/working/ gạch / ở vị trí 18