This example shows how auto can be used to shorten type declaration for for loops
std::map<int, std::string> Map;
for (auto pair : Map) // pair = std::pair<int, std::string>
for (const auto pair : Map) // pair = const std::pair<int, std::string>
for (const auto& pair : Map) // pair = const std::pair<int, std::string>&
for (auto i = 0; i < 1000; ++i) // i = int
for (auto i = 0; i < Map.size(); ++i) // Note that i = int and not size_t
for (auto i = Map.size(); i > 0; --i) // i = size_t