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From: Ehsan Salari on 27 Apr 2010 20:44
"Ehsan Salari" <ehsan.salari(a)gmail.com> wrote in message <hr7toa$brk$1(a)fred.mathworks.com>...
> "James Tursa" <aclassyguy_with_a_k_not_a_c(a)hotmail.com> wrote in message <hr7s00$k8c$1(a)fred.mathworks.com>...
> > "Ehsan Salari" <ehsan.salari(a)gmail.com> wrote in message <hr7p0c$b02$1(a)fred.mathworks.com>...
> > > Hello,
> > >
> > > I am trying to read a 2D array ("aper") from a mat file in C++ (Visual Studio) and assign it to a 2D array ("aper1"). I am using the following code:
> > >
> > > MATFile *pmat;
> > > mxArray *pa1;
> > > int ** aper1;
> > > aper = new int*[nbixel];
> > > for (int i = 0; i < nbixel; i++)
> > > {
> > > aper[i] = new int[3];
> > > }
> > > //////////
> > > pmat = matOpen(filename.c_str(), "r");
> > > pa1 = matGetVariable(pmat, "aper");
> > > aper1 = (int**)mxGetData(pa1);
> > > mxDestroyArray(pa1);
> > > matClose(pmat);
> > >
> > > I can read the variable "aper" but I cannot assign it to aper1. Could you please let me know how I can read a 2D array in C++? In particular, can I use mxGetData in case of a 2D array?
> > >
> > > Thanks!
> >
> > You need to copy each and every element *individually*. So you need to do this:
> >
> > int *pr; // assuming the variable in the mat file is an int32 class variable
> > :
> > pr = mxGetData(pa1);
> > for( etc. )
> > for( etc. )
> > aper1[i][j] = pr[etc.]
> >
> > You can fill in the details of the loops based on the size of pa1.
> >
> > You might also consider foregoing your 2D array in C and just go with a 1D array with linear indexing. Often this is easier to manage in your code.
> >
> > James Tursa
>
> Thanks a lot James! So pa1 should be treated is a 1 Dimensional array, but when I do this and I want to get pr[0] it gives me access violation error. I am not sure why.
>
> Ehsan

Actually, what I have noticed is that if I want to get pr[0] after destroying pa1 (i.e. mxDestroyArray(pa1)) then I get access violation but if I do it before that then I can easily get the element. Why is it the case?
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