A Typical Windows Installation

	Chapter 18 - Complete I/O in C++
	Visual C++ 6: The Complete Reference
	Chris H. Pappas and William H. Murray, III

Copyright 1998 The McGraw-Hill Companies

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	I/O Options

	Chapter 16 introduced the concepts and syntax for object-oriented classes, constructors, destructors, member functions, and operators. This knowledge is required for a deeper understanding of C++ I/O.

	C++, like C, does not have any built-in I/O routines. Instead, all C++ compilers come bundled with object-oriented iostream classes. These standard I/O class objects have a cross-compiler syntax consistency because they were developed by the authors of the C++ language. If you are trying to write a C++ application that is portable to other C++ compilers, you will want to use these iostream classes. The Visual C++ compiler provides the following five ways to perform C++ I/O:

	•		ANSI C buffered I/O C also supports buffered functions such as fread( ) and fwrite( ). These STDIO.H library functions perform their own buffering before calling the direct I/O base routines.

	•		C console and port I/O C provides additional I/O routines that have no C++ equivalent, such as _getch( ), _ungetch( ), and _kbhit( ). All non-Windows applications can use these functions, which give direct access to the hardware.

	•		Microsoft Foundation Class library The Microsoft CFile class found in the Foundation Class library provides C++, and especially Windows applications, with objects for disk I/O. Using this library of routines guarantees that your application will be portable and easy to maintain.

	•		Microsoft iostream class library The iostream class library provides C++ programs with object-oriented I/O. This I/O can be used in place of functions such as scanf( ), printf( ), fscanf( ), and fprintf( ). However, while these iostream classes are not required by C++ programs, many of the character-mode objects, such as cin, cout, cerr, and clog, are incompatible with the Windows graphical user interface.

	•		Unbuffered C library I/O The C compiler provides unbuffered I/O through functions such as _read( ) and _write( ). These functions are very popular with C programmers because of their efficiency and the ease with which they can be customized.

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