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

[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 !

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

}

//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

 //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;
	 }
           ..............

[Paul McKenzie]

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 !

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

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 (); */
}

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?

	delete [] s, e, w;

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:

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

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