Visual C++ provides several alternatives for I/O programming:
C run-time library direct, unbuffered I/O.
ANSI C run-time library stream I/O.
Console and port direct I/O.
Microsoft Foundation Class Library.
Microsoft Standard C++ Library.
The iostream classes are useful for buffered, formatted text I/O. They are also useful for unbuffered or binary I/O if you need a C++ programming interface and decide not to use the Microsoft Foundation Class (MFC) library. The iostream classes are an object-oriented I/O alternative to the C run-time functions.
You can use iostream classes with the Microsoft Windows operating system. String and file streams work without restrictions, but the character-mode stream objects cin, cout, cerr, and clog are inconsistent with the Windows graphical user interface. You can also derive custom stream classes that interact directly with the Windows environment.