c++ - C++11: how to use range-based for() loop with std::map? - Stack Overflow
From this paper: http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2006/n2049.pdf for( type-specifier-seq simple-declarator : expression ) statement syntactically equivalent to { typedef decltype(expression) C; auto&& rng(expression); for (auto begin(std ...