How to design a lowpass filter from Visual C++ using C shared library dll

I have to call the following code from Visual C++

 function z=lpf(x,n,fc,s)
 hl  = fdesign.lowpass('N,Fc', n, fc, s);
 Hdl = design(hl, 'butter');
 z=filter(Hdl,x);

Function name in header file is

 mlfLpf(int nargout, mxArray** z, mxArray* x
                   , mxArray* n, mxArray* fc, mxArray* s);

What are necessary steps to call this function successfully