FAQ 15.07 What are the tradeoffs between the various techniques for using names from a namespace, particularly the standard namespace?

Relying solely on the scope operator leads to programs that are hard to read, particularly for frequently used classes such as string. Clutter is not desirable in programs that have to be maintained.

The using declaration is probably the best solution for most cases, because the developer specifically declares what is intended. But this can be tedious, particularly when pulling names from the standard library.

The using directive is less desirable than the using declaration because it pollutes the global namespace unnecessarily and opens the door for later code breakage. This is because compiler writers and class library providers can add names to the standard namespace, which means that programs that utilize using namespace std; can suddenly fail to compile even though the user has not changed anything.

Despite this, we utilize using namespace std; throughout this book to allow our examples to compile and to allow the reader who has not read this chapter yet to muddle through, but this practice has little to recommend it.