problem in allocate and deallocating of memory in mexfunctio

I wrote very simple program in mex but have memory error.

#include "mex.h"

void mexFunction(int nlhs,mxArray *plhs[],int nrhs,const mxArray *prhs[])
{
    double *buf;
    int buflen=1000;
    long int index;

      /* Get number of characters in the input string.  Allocate enough
         memory to hold the converted string. */

      buf = mxMalloc(buflen);
      for (index=0;index<buflen;index++) 
          buf[index]=0;

      mexPrintf("The End of program:  %s\n", buf);
      mxFree(buf);
      return;
  }

Answer 1

[James Tursa]

The basic problem is you don't allocate enough memory for your doubles, since mxMalloc works in bytes. So do this instead:

      buf = mxMalloc(buflen * sizeof(*buf));

Also, you are attempting to print buf as a string using the %s format, i.e. a null terminated C-style string, when in fact buf is a (double *) type ... it points to doubles, not characters that have a null character at the end. If you want to print out the memory address, use %p instead. E.g.,

        mexPrintf("The End of program:  %p\n", buf);