how 2 read id #s from a text file

[LetsRideBaby]

that dont seem to work..

Here what im trying to do i have a website and i want the online users ids or names to be logged and if they have done been logged not to log them again..

this is way the str n = (place of user name or id on my site ) so i can make one for each index on the site where the username id is and this way it can log or skip them