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Is there a preprocessor definition which I could use in #ifdef checks to discern the different versions of C++ language?
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The C preprocessor is a macro processor that is used automatically by the C compiler to transform your program before actual compilation. It is called a macro processor because it allows you to define macros, which are brief abbreviations for longer constructs.
Examples of some preprocessor directives are: #include, #define, #ifndef etc. Remember that the # symbol only provides a path to the preprocessor, and a command such as include is processed by the preprocessor program.
A preprocessor directive is a statement (such as #define) that gives the preprocessor specific instructions on how to modify your source code. The preprocessor is invoked as the first part of your compiler program's compilation step.
Preprocessor directives, such as #define and #ifdef , are typically used to make source programs easy to change and easy to compile in different execution environments. Directives in the source file tell the preprocessor to take specific actions.
The value of the __cplusplus macro is supposed to serve this purpose. Unfortunately, GCC has (before 4.7) always set this to 1, making it unusable for this purpose.
(The values are 199711L for C++98/03, and 201103L for C++11.)
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