Access C++ static methods from C#

Question

Say you have following C++ code:

extern "C" {
    void testA(int a, float b) {
    }

    static void testB(int a, float b){
    }
}

I want to access this in my C# project using DllImport:

class PlatformInvokeTest
{
    [DllImport("test.so")]
    public static extern void testA(int a, float b);
    [DllImport("test.so")]
    internal static extern void testB(int a, float b);

    public static void Main() 
    {
        testA(0, 1.0f);
        testB(0, 1.0f);
    }
}

This works perfectly fine for testA, but testB fails throwing an EntryPointNotFoundException.

Can I access testB from my C# code? How?

Answer 1

static does not mean the same in C++ as it does in C#. At namespace scope, static gives a name internal linkage, meaning that it is only accessible within the translation unit that contains the definition. Without static, it has external linkage, and is accessible in any translation unit.

You will need to remove the static keyword when you want to use DllImport