Calling Matlab from C++: How to pass in no arguments in varargin?

I am compiling Matlab .m functions using Matlab compiler into libraries callable from C++. The particular function I am working with looks like this:

function status = cainit( model, varargin )
  if nargin==1
     % do something
  elseif nargin==2
     % do something else
  end
end

The C++ header file produced by Matlab compiler ("mcc") looks contains:

   extern LIB_libca_CPP_API void MW_CALL_CONV cainit( int nargout, mwArray& status, const mwArray& model, const mwArray& varargin );

I want to call cainit from my C++ code such that the nargin==1 part of the Matlab function gets executed. But I can't figure out how to pass in "no arguments".

For example, if I try the most obvious:

mwArray status;
cainit( 1, status, mwArray(""), mwArray() );

It still results in nargin==2 because mwArray() is an empty ([]) array.

Is there a way not to pass in an argument from C++? In other words, how do I do the C++ equivalent of Matlab "cainit('mymodel')"?

Thanks in advance!

Answer 1

[matal]

Looks like this is not possible:

http://www.mathworks.com/help/compiler/matlab-compiler-generated-interface-functions.html

"Caution The C++ shared library interface does not support varargin with zero (0) input arguments. Calling your program using an empty mwArray results in the compiled library receiving an empty array with nargin = 1. The C shared library interface allows you to call mlfFOO(NULL) (the compiled MATLAB code interprets this as nargin=0). However, calling FOO((mwArray)NULL) with the C++ shared library interface causes the compiled MATLAB code to see an empty array as the first input and interprets nargin=1."

Answer 2

[Kaustubha Govind]

I don't have a whole lot of experience with MATLAB Compiler, but does it work if you create varargin as an empty cell array and pass that in:

mwArray varargin(0, 0, mxCELL_CLASS);