Calling convention for an unmanaged DLL in C#

Question

I created a DLL in C++ and loaded in C# with [DllImport].

1. Is __cdecl default in C++ when exporting without calling convention?

2. Is it okay to use CallingConvention.StdCall or CallingConvention.Winapi with the function __cdecl? (It worked in my test, and I don't use 'Variable Arguments')

Answer 1

Is __cdecl default in C++ when exporting without calling convention?

Yes.

Is it okay to use CallingConvention.StdCall or CallingConvention.Winapi with the function __cdecl ?

No. Use CallingConvention.Cdecl . Using the wrong calling convention might appear to work for some functions, but it is wrong, and at some point you will be caught out.