C++: A Dialog Programming with the C++ Standard Library

Definitions

The preprocessor is a part of the C++ compiler that modifies the source code of a program seen by the rest of the compiler; thus, the name “preprocessor”. The preprocessor is needed to accomplish tasks that cannot be done by the rest of the compiler, e.g., to prevent declarations in a header file from being processed twice for the same implementation file.

A preprocessor directive is a command by which we tell the preprocessor to perform a specific task, e.g., to ignore a section of source code under certain conditions.

A preprocessor symbol is a constant value similar to a const that is known only to the preprocessor, not to the rest of the compiler. The rules for naming preprocessor symbols are the same as those for other identifiers, ...