Sams Teach Yourself C++ in 21 Days

Working with Streams 597

17

Streams and Buffers ............................................................................................

As you might expect, C++ takes an object-oriented view toward implementing streams

and buffers. It does this with the use of a number of classes and objects:

• The streambufclass manages the buffer, and its member functions provide the
  capability to fill, empty, flush, and otherwise manipulate the buffer.


• The iosclass is the base class to the input and output stream classes. The iosclass
  has a streambufobject as a member variable.


• The istreamand ostreamclasses derive from the iosclass and specialize input
  and output stream behavior, respectively.


• The iostreamclass is derived from both the istreamand the ostreamclasses and
  provides input and output methods for writing to the screen.


• The fstreamclasses provide input and output from files.
  You’ll learn more about these classes throughout the rest of today’s lesson.

Standard I/O Objects............................................................................................

When a C++ program that includes the iostreamclasses starts, four objects are created

and initialized:

FIGURE17.5
Flushing the buffer.