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What is STD in namespace?
“using namespace std” means we use the namespace named std. “std” is an abbreviation for standard. So that means we use all the things with in “std” namespace. If we don’t want to use this line of code, we can use the things in this namespace like this. std::cout, std::endl.
Is using nested classes bad?
Inner classes are frequently used, and something very similar – anonymous classes – are practically indispensable, as they are the closest thing Java has to closures. So if you can’t remember where you heard that inner classes are bad, try to forget about it! They’re not “bad” as such.
What’s the difference between unnamed namespaces and classes?
You can have unnamed namespaces. A namespace defines a new scope and members of a namespace are said to have namespace scope. They provide a way to avoid name collisions (of variables, types, classes or functions) without the inconvenience of handling nested classes. A class is a data type.
How is an inline namespace different from a nested namespace?
In contrast to an ordinary nested namespace, members of an inline namespace are treated as members of the parent namespace. This characteristic enables argument dependent lookup on overloaded functions to work on functions that have overloads in a parent and a nested inline namespace.
Can You reopen a namespace in a class?
You can reopen a namespace and add stuff across translation units. You cannot do this with classes. Using a class implies that you can create an instance of that class, not true with namespaces. You can use using-declarations with namespaces, and that’s not possible with classes unless you derive from them.
Do you have unqualified access to a nested namespace?
An ordinary nested namespace has unqualified access to its parent’s members, but the parent members do not have unqualified access to the nested namespace (unless it is declared as inline), as shown in the following example: