I have a problem about mex file!

I wrote the following file.c:

#include math.h #include matrix.h #include mex.h

void mexFunction(int nlhs, mxArray * plhs [], int nrhs, const mxArray * prhs []) { double * value; const mwSize * dimx; int nrows, ncolums; int i, j; int lunghy; int valz;

    char * stringaval;
    value = mxGetPr(prhs[0]);
    dimx = mxGetDimensions(prhs[0]);
    nrows = (int)dimx [0];
    ncolums = (int) dimx [1];
    for (i=0; i<nrows;i++)
   {
       for(j=0; j<ncolums; j++)
       {
           // stampo il valore float e vado a stampare la prima riga
           printf("%f",value [j*nrows+1]);
       }
       printf("%n");
   }
   lunghy = (int) mxGetN(prhs[1])+1;
   stringaval = mxCalloc(lunghy, sizeof(char));

   mxGetString(prhs[1],stringaval,lunghy);
   printf("%s",stringaval);

   valz = (int) mxGetScalar(prhs[2]);
   printf("%d\n",valz);

}

But, when I go to compile it on matlab >>mex mynamefile.c >>mynamefile([1 3 4;-1 -2 -4],'bye',10) matlab closes! I can't understand if there is an error in the code or is my matlab doesn't work. The version I am using is the Matalb R2013b Help me... please!

[Geoff Hayes]

Lucy - I was able to compile your program (without errors) once I put the correct angled brackets and double quotes around your include files

 #include <math.h> 
 #include "matrix.h" 
 #include "mex.h"

Replace your three lines with the above and try compiling again.

[Lucy]

I tried but it doesn't work, matlab is closed!

[Geoff Hayes]

Have you ever built any other MEX-functions? Have you run mex -setup?

[Lucy]

We've done other MEX-function, some functions work, others not. I have installed the compiler, but in my opinion, I think I have problems on matrices! Photo 1:

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Answer 1

[Geoff Hayes]

Lucy - I was able to reproduce the crash; MATLAB does not indeed close when you run the compiled program. The problem is with this line

 printf("%n");

I realize that you probably want a carriage return here, after printing out each row of the matrix. So please replace the above line with

 printf("\n");

The other line shouldn't cause a crash; even creating the function as a cpp file and including a try/catch block does not prevent this behaviour.

With the above fix, running your program produces

 >> g1([1 3 4;-1 -2 -4],'bye',10)
 -1.000000-2.000000-4.000000
 -1.000000-2.000000-4.000000
 bye10

Try the above and see what happens!

[Lucy]

OK! Thank you very much!