Roman Shchugarev wrote: > Hi > > Got myself in to trouble once again, it is said in libq header that to use > libpqxx I > need to define NOMINMAX option, but in that case I am unable to use #include < > afxtempl.h> (Using MS VisualStudio .NET2k3). What are the consequences of not > using NOMINMAX definition and just commenting out the error > #error "Oops: min() and/or max() are defined as preprocessor macros.\ > Define NOMINMAX macro before including any system headers!" > ?????
The problem is that windows.h defines max and min as macros while the C++ standard library defines std::max and std::min as function templates. The defines in windows.h give libpqxx trouble invoking std::max and std::min later on. This may lead to problems because, among other things: (a) std::max(a,b) will expand into std::BLAHMACROGARBLEETC, which isn't syntax compilers are likely to like. (b) Even if libpqxx invokes max and min without explicitly specifying the std:: namespace, then the macros will be called instead of the std:: versions, and the macros may cause side effects of their arguments to occur multiple times for one invocation, like this: int a = 2, b = 1; max(a++,b); std::cout << a; // may print more than 3. may cause (c) It's untested. :-) I can suggest two possible solutions: 1. Include afxtempl.h and all other system headers that require FIRST, then: #undef min #undef max and only then include libpqxx. 2. Include *all* that you need of libpqxx before including *any* Windows or MFC headers. Then NOMINMAX is not needed, as libpqxx will not be included with min and max defined. Cheers, Bart _______________________________________________ Libpqxx-general mailing list Libpqxx-general@gborg.postgresql.org http://gborg.postgresql.org/mailman/listinfo/libpqxx-general
