Accessing namespace Members with Qualified Names

Line 35 outputs the value of variable doubleInUnnamed, which is directly accessible as part of the unnamed namespace. Line 38 outputs the value of global variable integer1. For both of these variables, the compiler first attempts to locate a local declaration of the variables in main. Since there are no local declarations, the compiler assumes those variables are in the global namespace.

Lines 41–43 output the values of PI, E, integer1 and FISCAL3 from namespace Example. Notice that each must be qualified with Example:: because the program does not provide any using directive or declarations indicating that it will use members of namespace Example. In addition, member integer1 must be qualified, because a global variable has the same name. Otherwise, the global variable’s value is output. FISCAL3 is a member of nested namespace Inner, so it must be qualified with Example::Inner::.

Function printValues (defined in lines 49–55) is a member of Example, so it can access other members of the Example namespace directly without using a namespace qualifier. The output statement in lines 51–54 outputs integer1, PI, E, doubleInUnnamed, global variable integer1 and FISCAL3. Notice that PI and E are not qualified with Example. Variable doubleInUnnamed is still accessible, because it’s in the unnamed namespace and the variable name does not conflict with any other members of namespace Example. The global version of integer1 must be qualified with the scope resolution operator (::), because its name conflicts with a member of namespace Example. Also, FISCAL3 must be qualified with Inner::. When accessing members of a nested namespace, the members must be qualified with the namespace name (unless the member is being used inside the nested namespace).