What is using directive in namespace?

Question

Using directive syntax using namespace name ; The name must be a previously defined namespace. The using directive may be applied at the global and local scope but not the class scope. Local scope takes precedence over global scope by hiding similar declarations with some exceptions.

What directive is used to include namespaces?

The using directive can appear: At the beginning of a source code file, before any namespace or type declarations. In any namespace, but before any namespaces or types declared in that namespace, unless the global modifier is used, in which case the directive must appear before all namespace and type declarations.

What is the using directive in C++?

A using directive provides access to all namespace qualifiers and the scope operator. This is accomplished by applying the using keyword to a namespace identifier. The name must be a previously defined namespace.

Do not use namespace using directives?

Avoid using directives (particularly using namespace std; ), except in specific circumstances. Using declarations are generally considered safe to use inside blocks. Limit their use in the global namespace of a code file, and never use them in the global namespace of a header file.

Should using directive be inside or outside the namespace?

As a rule, external using directives (System and Microsoft namespaces for example) should be placed outside the namespace directive.

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