1. decltype

int nVariable1;
...
decltype(nVariable1)  nVariable2; //declares nVariable2 of int type

2. aliases

typedef std::unique_ptr<std::unordered_map<std::string, std::string>> UPtrMapSS;

// But typedefs are soooo C++98. They work in C++11, sure, but C++11 also offers alias declarations:
using UPtrMapSS = std::unique_ptr<std::unordered_map<std::string, st::string>>;