Namespace aliases

 

C++

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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