Is it possible to call a C function from C#.Net

Question

I have a C lib and want to call function in this library from C# application. I tried creating a C++/CLI wrapper on the C lib by adding the C lib file as linker input and adding the source files as additional dependencies.

Is there any better way to achieve this as am not sure how to add C output to c# application.

My C Code -

__declspec(dllexport) unsigned long ConnectSession(unsigned long handle,                             unsigned char * publicKey,                             unsigned char   publicKeyLen); 

My CPP Wrapper -

long MyClass::ConnectSessionWrapper(unsigned long handle,                                 unsigned char * publicKey,                                 unsigned char   publicKeyLen)     {         return ConnectSession(handle, publicKey, publicKeyLen);     } 

Answer 1

The example will be, for Linux:

1) Create a C file, libtest.c with this content:

#include <stdio.h>  void print(const char *message) {   printf("%s\\n", message); } 

That’s a simple pseudo-wrapper for printf. But represents any C function in the library you want to call. If you have a C++ function don’t forget to put extern C to avoid mangling the name.

2) create the C# file

using System;  using System.Runtime.InteropServices;  public class Tester {         [DllImport("libtest.so", EntryPoint="print")]          static extern void print(string message);          public static void Main(string[] args)         {                  print("Hello World C# => C++");         } } 

3) Unless you have the library libtest.so in a standard library path like “/usr/lib”, you are likely to see a System.DllNotFoundException, to fix this you can move your libtest.so to /usr/lib, or better yet, just add your CWD to the library path: export LD_LIBRARY_PATH=pwd

credits from here

EDIT

For Windows, it's not much different. Taking an example from here, you only have yo enclose in your *.cpp file your method with extern "C" Something like

extern "C" { //Note: must use __declspec(dllexport) to make (export) methods as 'public'       __declspec(dllexport) void DoSomethingInC(unsigned short int ExampleParam, unsigned char AnotherExampleParam)       {             printf("You called method DoSomethingInC(), You passed in %d and %c\n\r", ExampleParam, AnotherExampleParam);       } }//End 'extern "C"' to prevent name mangling 

then, compile, and in your C# file do

[DllImport("C_DLL_with_Csharp.dll", EntryPoint="DoSomethingInC")]  public static extern void DoSomethingInC(ushort ExampleParam, char AnotherExampleParam); 

and then just use it:

using System;      using System.Runtime.InteropServices;      public class Tester     {             [DllImport("C_DLL_with_Csharp.dll", EntryPoint="DoSomethingInC")]      public static extern void DoSomethingInC(ushort ExampleParam, char AnotherExampleParam);              public static void Main(string[] args)             {                     ushort var1 = 2;                     char var2 = '';                       DoSomethingInC(var1, var2);             }     }