1.3 ANSI C++

The American National Standards Institution (ANSI) provides "official" and generally accepted standard definitions of many programming languages, including C and C++. Such standards are important. A program written only in ANSI C++ is guaranteed to run on any computer whose supporting software conforms to the ANSI standard. In other words, the standard guarantees that ANSI C++ programs are portable. In practice most versions of C++ include ANSI C++ as a core language, but also include extra machine-dependent features to allow smooth interaction with different computers' operating systems. These machine dependent features should be used sparingly. Moreover, when parts of a C++ program use non-ANSI components of the language, these should be clearly marked, and as far a possible separated from the rest of the program, so as to make modification of the program for different machines and operating systems as easy as possible.