A way How to Compile C library into .Net dll ?

Question

Can we compile C library as .Net dll (containing and opening access to all C libs functions) by just compiling cpp project containing code like

extern "C" {
#include <library.h>
}

with /clr:pure argument with VS? (VS10)

Or we should do something more trickey?

Answer 1

It really depends on your C code.

P/Invoke is often the easiest to start with, and IMO is pretty workable for a handful of functions. Performance isn't necessarily great, and I wouldn't construct an entire program out of it - but to reuse some functions, it's worthwhile.

Going from C to /clr:pure requires you to:

1. Convert your C code to C++
2. Convert your C++ code to Visual C++
3. Compile with /clr option
4. Compile with /clr:pure

The current state of your code (and it's libraries) will dictate how painful that process is.

Answer 2

I found it is the best to use the old style Managed C++ for this.

CLR:PURE just wont cut it.

Example:

extern "C" int _foo(int bar)
{
  return bar;
}

namespace Bar
{
  public __gc class Foo
  {
  public:
    Foo() {}

    static int foo(int bar)
    {
      return _foo(bar);
    }
  };
};

Compile with: /clr:oldSyntax

Now you can reference the assebmly, and call Bar.Foo.foo() from .NET.

Answer 3

It's not generally a given that you can even compile C code as C++ without making some changes. If you can get your C code to compile as C++, then you can try getting it to compile as C++/CLI (that's what the clr:pure option does).

At that point, you can create some kind of class which exposes all your exported functions as static methods of a public (managed) class.

Some flavours of this sort of stuff can be done with C++ preprocessor tricks (macros, etc), sometimes you end-up writing wrappers manually.

So the basic information that you can compile C++ into .NET assemblies using /clr:xxx options is true, but that doesn't mean it's the only thing you need to do to get a useful .NET assembly.