what's wrong with delete [] a[0];

Hi all ,
I wrote a program, but there is a problem, it reminds "debug error!", I have found that the problem was in "ginv:: ~ginv (){}" but I don't know how to solve it,can anyone help me with this, thank you !

Code:

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void CCalginvView::OnCalginv()
{
        // TODO: Add your command handler code here
        ginv  uv(5, 4);
        uv.input ();        //由文件读入矩阵A的元素以及eps
        uv.a_ginv ();          //计算广义逆
        uv.output ();        //输出U矩阵和V矩阵以及奇异值

}

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Code:

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//1GINV.h
  #ifndef GINV_H_H
  #define GINV_H_H

  #include  <iostream>
  #include  <fstream>
  #include  <cmath>
  using namespace std;
  class  ginv
  {
  private:
          int m, n, ka;
          double  **a, **u, **v, **aa, eps;
          double  *s, *e, *w, fg[2], cs[2];
       
  public:
        ginv (int mm, int nn);
                void input ();       
        void uav ();          //svd
          void ppp();           
          void sss();           
          void a_ginv ();       
        void output ();       
        ~ginv ();
  };
  #endif

---

Code:

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//1GINV.CPP
  #include "stdafx.h"
  #include  <iostream.h>
  #include  <fstream.h>
  #include  <math.h>
  #include "ginv.h"


#ifdef _DEBUG
#define new DEBUG_NEW
#undef THIS_FILE
  static char THIS_FILE[] = __FILE__;
#endif
ginv::ginv (int mm, int nn)
        {
                          int i;
                          m = mm; n= nn;
                  a = new double*[m];  //动态分配内存空间
                  for (i=0; i<m; i++) a[i] = new double[n];
                  u = new double*[m];
                  for (i=0; i<m; i++) u[i] = new double[m];
                  v = new double*[n];
                  for (i=0; i<n; i++) v[i] = new double[n];
                  aa = new double*[n];
                  for (i=0; i<n; i++) aa[i] = new double[m];
              ka = m + 1;
                  if (m < n)  ka = n + 1;
              s = new double[ka];
              e = new double[ka];
              w = new double[ka];
        }       

ginv:: ~ginv ()
        {
        int i;
       
        for (i=0; i<m; i++)        { delete []a[i]; }
        delete [] a;
        for (i=0; i<m; i++) { delete [] u[i]; }
        delete [] u;
        for (i=0; i<n; i++) { delete [] v[i]; }
        delete [] v;
        for (i=0; i<n; i++) { delete [] aa[i]; }
        delete [] aa;
                delete [] s, e, w;
        }
          ..............

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Quote:

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Originally Posted by Angela2010

Hi all ,
I wrote a program, but there is a problem, it reminds "debug error!", I have found that the problem was in "ginv:: ~ginv (){}" but I don't know how to solve it,can anyone help me with this, thank you !

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For the sake of others, here is full, runnable version of your program:

Code:

---

class  ginv
{
  private:
          int m, n, ka;
          double  **a, **u, **v, **aa, eps;
          double  *s, *e, *w, fg[2], cs[2];
       
  public:
        ginv (int mm, int nn);
        void input ();       
        void uav ();          //svd
        void ppp();           
        void sss();           
        void a_ginv ();       
        void output ();       
        ~ginv ();
};


ginv::ginv (int mm, int nn)
{
  int i;
  m = mm; n= nn;
  a = new double*[m];  //动态分配内存空间
  for (i=0; i<m; i++)
        a[i] = new double[n];

  u = new double*[m];
  for (i=0; i<m; i++)
        u[i] = new double[m];

  v = new double*[n];
  for (i=0; i<n; i++)
      v[i] = new double[n];

  aa = new double*[n];
  for (i=0; i<n; i++)
        aa[i] = new double[m];

  ka = m + 1;
  if (m < n) 
          ka = n + 1;
  s = new double[ka];
  e = new double[ka];
  w = new double[ka];
}       

ginv:: ~ginv ()
{
        int i;
       
        for (i=0; i<m; i++)       
            { delete []a[i]; }
        delete [] a;

        for (i=0; i<m; i++)
            { delete [] u[i]; }
        delete [] u;

        for (i=0; i<n; i++)
            { delete [] v[i]; }

        delete [] v;
        for (i=0; i<n; i++)
            { delete [] aa[i]; }

        delete [] aa;
        delete [] s, e, w;
}

int main()
{
    ginv  uv(5, 4);
/*    uv.input ();
    uv.a_ginv ();
    uv.output (); */
}

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First, where is the input() function? Where is the output function? Where is the a_ginv() function? You're calling all of these functions, and we have no idea if these functions are causing the problem.

Second, what is this line supposed to do?

Code:

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        delete [] s, e, w;

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What book or tutorial shows you that this is the way to deallocate multiple data items using "delete"? The delete works on one item at a time, not multiple items on the same line. This code does things that you don't expect it to do.

Third, you could easily have just used CArray or std::vector instead of all of these allocations/deallocations. Then you're problems would have disappeared.

Last, your ginv class lacks a proper user-defined copy constructor and assignment operator. I can easily break your code with a three line program:

Code:

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int main()
{
  ginv gv1(2,2);
  ginv gv2(3,3);
  gv1 = gv2;
}

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That three line program has a memory leak, plus it's calling delete on the same pointer value more than once when gv1 and gv2 are destroyed.

Regards,

Paul McKenzie