using namespace I make the whole contents of that namespace directly visible without using the namespace qualifier. This can cause problems if
using namespace occurs in widely used headers – we can unintendedly make two namespaces with identical classes names visible and the compiler will refuse to compile unless the class name is prepended with the namespace qualifier.
Can I undo
using namespace so that the compiler forgets that it saw it previously?
No, but you can tell your coworkers that you should never have a
using directive or declaration in a header.
Answered By – rlbond
Answer Checked By – Candace Johnson (AngularFixing Volunteer)