static library wrapping problem

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Hi,

I am getting quite frustrated while trying to wrap a C++ static library
using managed C++ to a dll.

Here are what I tried
first, try to wrap it is a normal dll with some functions. seems everything
ok.

second, tried to wrap it use VS2003->C++ .NET dll project, implement the
same functions, disabled the precompiled header. Cannot compile.

third, for project created in the first step, I set Use Managed Extensions
as yes and recompile. Recompiled and the new dll can be referenced by my C#
test code.

I use same headers for both projects. The difference is some standard
library automatically generated with .NET dll project and extra using
namespace System statement, which comes with the project. (remove this using
statement still generate compiling error).

Can someone tell me the difference between 2 and 3 to generate a managed C++
dll project?

I tried to play with project settings in approach 2, not successful, until I
give up and go with method 3.

Thanks

Chris