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The following examples illustrate the use of conditional compilation using the OpenMP macro _OPENMP (Section 2.2 on page 8). With OpenMP compilation, the _OPENMP macro becomes defined.
# ifdef _OPENMP
printf_s("Compiled by an OpenMP-compliant implementation.\n");
# endif
The defined preprocessor operator allows more than one macro to be tested in a single directive.
# if defined(_OPENMP) && defined(VERBOSE)
printf_s("Compiled by an OpenMP-compliant implementation.\n");
# endif