The Format Flags

The I/O Headers

The Standard C++ I/O system relies upon several headers. They are shown here:

Header	For
<fstream>	File I/O
<iomanip>	Parameterized I/O manipulators
<ios>	Basic I/O support
<iosfwd>	Forward declarations used by the I/O system
<iostream>	General I/O
<istream>	Basic input support
<ostream>	Basic output support
<sstream>	String-based streams
<streambuf>	Low-level I/O support

Several of these headers are used internally by the I/O system. In general, your program will only include <iostream>, <fstream>, <sstream>, or <iomanip>.