Disk File I/O with streams:
Most of the programs need to save
data on disk file I/O. Working with disk file I/O requires another set of
classes: Such as ifstream class for user
input, fstream class for using both input and output, and ofstream for output.
Objects of these classes can be associated with disk files, and they can use
their member functions to read and write to the files.
In C++ programming ifstream class
is derived from istream class, fstream class is derived from iostream class,
and ofstream class is derived from ostream class.
The file-oriented classes are
also derived, by multiple inheritance, from the fstream base class. This class
contains an object of class filebuf, which is a file-oriented buffer, and its
associated member functions, derived from the more general streambuf class.
In formatted I/O, numbers are
stored on the disk as a series of characters. It can read the file generated using
an ifstream object. The file is automatically opened when the object is
created. It can then read from it using the extraction (>>) operator.