C# 中的内联 C 和编译？

Question

Is it possible to write majority of your program in say C# and then drop down and do certain functions/objects in C or C++?

I know you can call pre-compiled.dlls from C#; but can you do 'inline' native C directly from C#? Do they have to be "managed".dlls?

If not, I'm assuming there is a JNI like interface?

Also, another question; can you compile C# down into "native" machine code?

MSVS2010/Win7 if it matters.

Answer 1

You can't inline C code in C# - if you want to write part of your code in C then you will need to cross some sort of interop layer in order to call that C code, for example P/Invoke or Managed C++.

You can however inline C (or even assembly) in Managed C++, allowing you to combine native code and managed code in a single assembly / dll.

For the.Net equivalent of JNI, (native code calling managed code) the normal method is to either use COM interop or Managed C++ - you can also host the CLR, but this is less common.

As for compiling C# down into "native" machine code, read up on NGen .

Answer 2

Native C/C++ can be called using PInvoke (DllImport) from C#, or by C++/CLI code (.NET C++) or via COM. This is referred to as interop.

PInvoke requires native code to be exposed via DllExport.

C++/CLI and native code can be placed in same DLL or even cpp file.

C# (.NET) code is compiled to MSIL, which is translated on first access to machine code (JIT). It can be stored in advanced in GAC already translated to machine code, however, that only improves first access.

The equivalent C# code to C code should perform the same. C# even allows pointers in unsafe code, however not with templates as C++ does.

MSIL even has optimization that enable improving performance on dome cases.

I have seen demos of parallel calculations run faster in C# than equivalent C++.

If you design your C# wisely, performance will be good. Same goes to native C/C++.