What is the ios in CPP.....?

Question

I have seen iostream and fstream classes, and in both of them certain functions like setf() in iostream and open() in fstream class uses certain flags. To set those flags we need to use ios:: flag_name, eg(ios::left | ios::showpos) for the iostream , (ios::in| ios::app)...What is this ios...?

Answer 1

If I am not wrong, ios should be input-output-stream. Check out more here: http://www.cplusplus.com/doc/tutorial/files/

Answer 2

I hope these help: http://www.cplusplus.com/reference/ios/
http://www.cplusplus.com/reference/iostream/
https://stackoverflow.com/questions/22645097/what-does-include-iostream-do
http://www.cplusplus.com/reference/fstream/fstream/
https://stackoverflow.com/questions/8295320/how-can-i-use-flag-coding