ASP.NET is a web development environment, where HTML code and program logic
are intermingled.  ASP.NET supports embedding C# or Visual Basic code inside
.aspx pages and for code-behind, but does not support C++.  The reason for
this is probably that C++ is far more complex to parse than either C# or
Visual Basic.

However, an ASP.NET page can reference classes from a .NET assembly written
in any language.  Therefore, the canonical way to use C++ in ASP.NET is:
compile business logic in a C++/CLI managed class library.  Register that
assembly in the global assembly cache and reference it from a C# web
project.  Use C# to stitch the HTML interface to the C++ backend.

And to ChristiG -- Your arrogant response demonstrates a lack of
interpersonal skills.  Calling someone's question stupid is inappropriate
for this list, and it is especially ironic when it is a valid question above
your level of expertise.