是否可以从 C#.Net 调用 C 函数 [英] Is it possible to call a C function from C#.Net

问题描述

我有一个 C 库，想从 C# 应用程序调用这个库中的函数.我尝试通过将 C lib 文件添加为链接器输入并将源文件添加为附加依赖项，在 C lib 上创建 C++/CLI 包装器.

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.

有没有更好的方法来实现这一点，因为我不确定如何将 C 输出添加到 C# 应用程序中.

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

我的 C 代码 -

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

我的 CPP 包装器 -

My CPP Wrapper -

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

推荐答案

示例如下，对于 Linux:

1) 使用以下内容创建一个 C 文件，libtest.c:

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

#include <stdio.h>

void print(const char *message)
{
  printf("%s\n", message);
}

这是一个简单的 printf 伪包装器.但代表您要调用的库中的任何 C 函数.如果您有 C++ 函数，请不要忘记放置 extern C 以避免修改名称.

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) 创建C# 文件

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) 除非你在像​​/usr/lib"这样的标准库路径中有库 libtest.so，否则你很可能会看到 System.DllNotFoundException，要解决这个问题，你可以将 libtest.so 移动到/usr/lib，或者更好的是，只需将您的 CWD 添加到库路径:export LD_LIBRARY_PATH=pwd

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

学分来自这里

编辑

对于Windows，没有太大的不同.以此处为例，您只需把你的方法用 extern "C" 包含在你的 *.cpp 文件中类似的东西

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

", ExampleParam, AnotherExampleParam);
      }
}//End 'extern "C"' to prevent name mangling

然后，编译，并在你的 C# 文件中做

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);

然后使用它:

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);
            }
    }

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