Hi George > Do you mean _DEBUG is not defined and used by gcc itself on Linux platform... Correct (as far as I am aware). >... and it may be used in application code? That's a qualified "yes". You *CAN* use it, but with a caveat. It is against the C++ standard (ISO 14882) to use it, since identifiers that begin with an underscore-followed-by-capital-letter are reserved. (Also, any identifier with the underscore-underscore sequence anywhere in the identifier are reserved.) >...especially the ones from Microsoft Windows platform... That would be one reason to contemplate breaking the ISO 14882 rules. HTH, --Eljay
