Testing
Testing . You are using auto so you have c++11 code. #include <<strong>unordered_map</strong>> (no need for tr1!). Testing from gcc.gnu.org You need a c++11 compliant compiler (e.g. A hash_map is an older, unstandardized version of what for standardization purposes is called an unordered_map (originally in tr1, and included in the standard since c++11). Being templates, they can be used to store arbitrary elements, such as integers or custom classes.the following containers are defined in the current revision of the c++ standard: