Return **C.Char

[AlexDias79]

Been trying to return a string, not printing it to console, but there seem not to be a way.

I did try 2 different approaches

//export PrintHello2
func PrintHello2(Input *C.char, Output **C.char) int32 {
	*Output = C.CString(fmt.Sprintf("From DLL: Hello, %s!\n", C.GoString(Input)))
	return 1
}

and

//export PrintHello4
func PrintHello4(Input *C.char) *C.char{
	return C.CString(fmt.Sprintf("From DLL: Hello, %s!\n", C.GoString(Input)))
}

I'm calling this code from .net using the following test code

class Program
{
	[DllImport("goDLL.dll", CharSet = CharSet.Unicode, CallingConvention = CallingConvention.Cdecl)]
	public static extern int PrintHello2([In] byte[] data, [MarshalAs(UnmanagedType.I1)] ref SByte[] output);

	[DllImport("goDLL.dll", CharSet = CharSet.Unicode, CallingConvention = CallingConvention.StdCall)]
	public static extern SByte[] PrintHello4(byte[] data);

	static void Main(string[] args)
	{
		string res = "demo";
		SByte[] output= { };

		Console.WriteLine("PrintHello4 Returns: " + PrintHello4(Encoding.UTF8.GetBytes(res)).Length);

		Console.WriteLine("PrintHello2 Returns: " + PrintHello2(Encoding.UTF8.GetBytes(res), ref output));
		Console.WriteLine("Ref Val changed to: " + output.Length + "\n");
	}
}

None of the Go function works as expected and program chashes with System.Runtime.InteropServices.MarshalDirectiveException for any of the 2 functions

[AlexDias79]

My bad, problem was in .net

Solution:
https://stackoverflow.com/questions/48208098/using-generated-golang-dll-to-return-string-or-c-char/48227520#48227520

[z505]

Good to hear there was a solution, I will close the issue now