What's the scope of the “using” declaration in C++?

Question

I\'m using the \'using\' declaration in C++ to add std::string and std::vector to the local namespace (to save typing unnecessary \'std::\'s).

using std::str         


        

Answer 1

There's nothing special about header files that would keep the using declaration out. It's a simple text substitution before the compilation even starts.

You can limit a using declaration to a scope:

void myFunction()
{
   using namespace std; // only applies to the function's scope
   vector myVector;
}