C++ variable file

hello. i'm solving a little problem. i have an app, but there is a lots of outputs in there, and it's slowing down my app. so i think if i save this string used for cout into a file, i will solve this problem. i have some libraries for ini files, but ini is not what i need. i need only simple text file, i know how to write into file, but i don't know how to read a specific line in file. how can i do this? thanks.

http://www.cplusplus.com/doc/tutorial/files.html

http://www.google.com.eg/search?q=reading+files+C%2B%2B

And actually, you can find this in any C++ full tutorial / book.

thanks