Ok. Better framed question. The following is compiled on XCode 5.0.1. Clang : Apple LLVM version 5.0 (clang-500.2.79) (based on LLVM 3.3svn) Target: x86_64-apple-darwin12.5.0 Thread model: posix Boost v 1.55.0. Build 2.0-m12. Not sure how to fix it. map complains about constructor ambiguity and I am not sure how to fix it. I am a casual hobbyist programmer and not a C++ expert. Looking at boost headers confuses me. Any help would be appreciated. //--------------------------------------------------------------------- Header File #ifndef boostTest_test_h #define boostTest_test_h #include #include #include using namespace boost::multiprecision; typedef std::map TestMap; #endif //------------------------------------------------------------------------- C++ file #include #include "test.h" int main(int argc, const char * argv[]) { static TestMap tm; std::string s="hello"; int128_t n=128; tm[n]=s;