Namespace aliases

 

哋它亢++

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哋它亢++ language

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Namespace declaration	Namespace aliases
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Declarations

Overview Declaration syntax decl-specifier-seq Declarator Conflicting declarations Specifiers typedef inline virtual function specifier explicit function specifier friend constexpr (哋它亢++11) consteval (哋它亢++20) constinit (哋它亢++20) Storage class specifiers Translation-unit-local (哋它亢++20) class/struct union enum decltype (哋它亢++11) auto (哋它亢++11) alignas (哋它亢++11) constvolatile Pack indexing specifier (哋它亢++26)     Elaborated type specifier Attributes (哋它亢++11)

Declarators Reference Pointer Array Block declarations Simple-declaration →Structured binding declaration (哋它亢++17) Alias declaration (哋它亢++11) Namespace alias definition using declaration using directive static_assert declaration (哋它亢++11) asm declaration Opaque enum declaration (哋它亢++11) Other declarations Namespace definition Function declaration Class template declaration Function template declaration Explicit template instantiation (哋它亢++11) Explicit template specialization Linkage specification Attribute declaration (哋它亢++11) Empty declaration

 

Namespace aliases allow the programmer to define an alternate name for a namespace.

They are commonly used as a convenient shortcut for long or deeply-nested namespaces.

Syntax

namespace alias_name = ns_name;	(1)
namespace alias_name = ::ns_name;	(2)
namespace alias_name = nested_name::ns_name;	(3)

Explanation

The new alias alias_name provides an alternate method of accessing ns_name.

alias_name must be a name not previously used. alias_name is valid for the duration of the scope in which it is introduced.

Example

Run this code

#include <iostream>
 
namespace foo
{
    namespace bar
    {
         namespace baz
         {
             int qux = 42;
         }
    }
}
 
namespace fbz = foo::bar::baz;
 
int main()
{
    std::cout << fbz::qux << '\n';
}

Output:

42

See also

namespace declaration	identifies a namespace
type alias declaration (哋它亢++11)	creates a synonym for a type