reading and writing to *.dat files

[Mystic_D]

I want to write info to .dat files but i can't write more then 1 line while i want to write something like this:

Lokaal 251
10.42.251.1
10.42.251.2
10.42.251.3
10.42.251.4

And i want to read it line by line (just like .ini)
how do i do this ???