i know how to read a file, but how do i read only a certain line of a file?

You know that you've found the end of the line when you encounter a '\n' character. If you count those, you'll know which line you're up to and can take some action on it.

u have to know what he means by a line. if u use the standard programming definition then buzgub is okay. but if u wanna read a line like notepad wraps it to be, then u have to know the last character.
ignore this please if it seems im just blabbing

Yes. Disregard whizkide comment. Buzbug is right. All you have to care about is \n.

std::getline (std::istream, std::string[, char eol]);

Reads from the istream into the string. You can specify the line delimiter as an optional third argument that defaults to '\n'.

dont forget good old endl; the end line on a cout

Huh? std::endl inserts '\n' into an output stream. It has nothing to do with reading.