Common Predefined Macros (The C Preprocessor)3.7.2 Common Predefined Macros ¶ The common predefined macros are GNU C extensions. They are available with the same meanings regardless of the machine or operating system on which you are using GNU C or GNU Fortran. Their names all start with double underscores. __COUNTER__ This macro expands to sequential integral values starting from 0. In conjunction with the ## operator, this provides a conve
