How to: Detect /clr Compilation
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The latest version of this topic can be found at How to: Detect -clr Compilation.
Use the _MANAGED or _M_CEE macro to see if a module is compiled with /clr. For more information, see /clr (Common Language Runtime Compilation).
For more information about macros, see Predefined Macros.
Example
// detect_CLR_compilation.cpp
// compile with: /clr
#include <stdio.h>
int main() {
#if (_MANAGED == 1) || (_M_CEE == 1)
printf_s("compiling with /clr\n");
#else
printf_s("compiling without /clr\n");
#endif
}