Hi mahmoodn, > The file has the extension hxx. I searched and some say that hash_map is not stanrad in GCC. Correct, <hash_map> header is not standard C++, therefore it is not in the standard C++ headers with GCC. Boost provides a hash map for C++. <http://www.boost.org/> The GCC I am using provides a hash map (but I'm not sure if all GCC's provide a hash map): #include <ext/hash_map> __gnu_cxx::hash_map<int, int> mymap; The next standard of C++ will provide a hash map, through <unordered_map> header. If your GCC is more current than mine, you may have that available to you now. (You probably need to set -std= correctly.) HTH, --Eljay
