python File I/O write to another line questions

alright, so to get to the point my problem lies in a very simple question, using the .write() and .writelines() functions of python, how can you make it so that it write to another line. For example, say I want the strings '123', and '456' on two different lines, so that when you call example.dat for reading, readlines(0) returns 123 and readlines(1) returns 456.

or

or


In short, you have to add the newline character "\n".

I thought so too, but whenever I add the newline character in any of the above mentioned ways, readlines(0) and readlines(1) just return [], which i'm taking to mean an empty string. While read() just returns a giant string, though this may be what it does and I'm just being silly. Does it have something to do with the file I'm writing to being a .dat? Or is my understanding of Strings skewed by considering them to be arrays?

read() reads the whole file at once and returns a single string, so you'd have to split on newlines. readlines() should be returning both lines in an array. readline() (note the "s") reads one line at a time.

There's no hard and fast rule as far as the format of a .dat file. If you don't know what it does or how it's formatted, why are you trying to write to it? Do you even have write permissions to it?

Im writing to it to figure out what it does. Im also writing to it because if i had the correct hypothesis, it would make it easier than telling the code to splice at /n. I also do have permission to write to it. Your explanation of read() makes sense. If you have annything else to say, than i'd be glad to hear it.