Hi James, Assuming that your macro is called "MagicFn" (with $dostuff$ doing the appropriate thing)... #define MagicFn(MacroParm) $dostuff$ ...where you use the macro you can do this at invocation: #ifndef MyParm #error MyParm must be a macro #endif MagicFn(MyParm) If, instead, you want to do something like this... #define MagicFn(MacroParm) \ #ifndef MacroParm \ #error MacroParm must be a macro \ #endif \ $dostuff$ ... you can't do it in C/C++ with the C/C++ preprocessor. The only way to do that is to run a PRE-preprocessor of your own devising. You could write one that would be sufficient in Flex & Bison, or Perl, or sed. HTH, --Eljay
