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<h4 class="subsection">A.2.4 Cell Arrays with Mex-Files</h4>

<p>We can perform exactly the same operations in Cell arrays in mex-files
as we can in oct-files.  An example that reduplicates the functional of
the <samp><span class="file">celldemo.cc</span></samp> oct-file in a mex-file is given by
<samp><span class="file">mycell.c</span></samp> as below

<pre class="example"><pre class="verbatim">     #include "mex.h"
     
     void
     mexFunction (int nlhs, mxArray* plhs[], int nrhs, 
     	     const mxArray* prhs[])
     {
       mwSize n;
       mwIndex i;
     
       if (nrhs != 1 || ! mxIsCell (prhs[0]))
         mexErrMsgTxt ("expects cell");
     
       n = mxGetNumberOfElements (prhs[0]);
       n = (n > nlhs ? nlhs : n);
       
       for (i = 0; i &lt; n; i++)
         plhs[i] = mxDuplicateArray (mxGetCell (prhs[0], i));
     }
</pre>
</pre>
   <p class="noindent">which as can be seen below has exactly the same behavior as the oct-file
version.

<pre class="example">     [b1, b2, b3] = mycell ({1, [1, 2], "test"})
     &rArr;
     b1 =  1
     b2 =
     
        1   2
     
     b3 = test
</pre>
   <p>Note in the example the use of the <code>mxDuplicateArray</code> function.  This
is needed as the <code>mxArray</code> pointer returned by <code>mxGetCell</code>
might be deallocated.  The inverse function to <code>mxGetCell</code> is
<code>mcSetCell</code> and is defined as

<pre class="example">     void mxSetCell (mxArray *ptr, int idx, mxArray *val);
</pre>
   <p>Finally, to create a cell array or matrix, the appropriate functions are

<pre class="example">     mxArray *mxCreateCellArray (int ndims, const int *dims);
     mxArray *mxCreateCellMatrix (int m, int n);
</pre>
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