Why is including “using namespace” into a header file a bad idea in C++?
While reading from Bruce Eckel's "Thinking in C++" about namespaces, I encountered the following statement: However you'll virtually never see a using directive in a header file (at least not outside of scope). The reason is that using directive eliminate the protection of that particular namespace, and the effect last until the end of current compilation unit. If you put a using directive (outside of a scope) in a header file, it means that this loss of "namespace protection" will occur within any file that include this header, which often mean other header files. Would you please like to