using

#using
using

#using file


where: 
file 
A .dll, .exe, .netmodule, or .obj that was built with /clr.

ex.


#using <mscorlib.dll>
#using <System.dll>
 

file can be a Microsoft intermediate language (MSIL) file that you import for its managed data and managed constructs. If a .dll file contains an assembly manifest, then all the .dlls referenced in the manifest are imported and the assembly you are building will list file in the metadata as an assembly reference.


The LIBPATH environment variable specifies the directories that will be searched when the compiler tries to resolve file names passed to #using.


using

 

using-directive:
using namespace ::opt nested-name-specifieropt namespace-name

The using directive allows the names in a namespace to be used without the namespace-name as an explicit qualifier. Of course, the complete, qualified name can still be used to improve readability.