What is namespace std
Todas esas bibliotecas han sido rescritas en el espacio con nombre std. Hay que decir que todas estas funciones no son imprescindibles, y de hecho no forman parte del C. Sin responder. Formular una pregunta. Vista 37k veces. Mejora esta pregunta. Angel Angel Angel Angel 9, 9 9 medallas de oro 36 36 medallas de plata 68 68 medallas de bronce. Espero que no te moleste. Saludos — Angel Angel. Sin embargo considera el siguiente escenario: Estas utilizando dos bibliotecas llamadas Foo y Bar y en un momento dado decides importar los espacios de nombres: using namespace foo; using namespace bar; Todo funciona bien, puedes llamar Bla de Foo y a quux de Bar y sin problemas.
Mejora esta respuesta. If names used by these were out in the open, for example, if they defined a queue class globally, you'd never be able to use the same name again without conflicts. So they created a namespace, std to contain this change. The using namespace statement just means that in the scope it is present, make all the things under the std namespace available without having to prefix std:: before each of them. While this practice is okay for short example code or trivial programs, pulling in the entire std namespace into the global namespace is not a good habit as it defeats the purpose of namespaces and can lead to name collisions.
The following example shows how you can declare a specialization in a parent of a template that is declared in an inline namespace:. You can use inline namespaces as a versioning mechanism to manage changes to the public interface of a library. For example, you can create a single parent namespace, and encapsulate each version of the interface in its own namespace nested inside the parent. The namespace that holds the most recent or preferred version is qualified as inline, and is therefore exposed as if it were a direct member of the parent namespace.
Client code that invokes the Parent::Class will automatically bind to the new code. Clients that prefer to use the older version can still access it by using the fully qualified path to the nested namespace that has that code. The inline keyword must be applied to the first declaration of the namespace in a compilation unit. The following example shows two versions of an interface, each in a nested namespace. Code that attempts to call Contoso::Funcs::Divide will now get a compile time error.
Namespace names need to be unique, which means that often they should not be too short. If the length of a name makes code difficult to read, or is tedious to type in a header file where using directives can't be used, then you can make a namespace alias which serves as an abbreviation for the actual name.
This is called an unnamed or anonymous namespace and it is useful when you want to make variable declarations invisible to code in other files i. All code in the same file can see the identifiers in an unnamed namespace but the identifiers, along with the namespace itself, are not visible outside that file—or more precisely outside the translation unit.
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