RE: [Dev-C++] memory violation....

[Raghunath Marella.S <ms...@ya...>]

Hi,

Please find my reply embedded...

--- Ioannis Vranos <no...@ho...> wrote:
> > -----Original Message-----
> > From: dev...@li... 
> > [mailto:dev...@li...]
> On Behalf 
> > Of Raghunath Marella.S
> > Sent: Monday, June 10, 2002 10:25 AM
> > To: Dev-C++ Mailing List
> > Subject: RE: [Dev-C++] memory violation....
> > 
> > 
> > Hi Ioannis/Jason/Others,
> > 
> > Please find the piece of code where the memory
> > violation is seen. I have not deleted the pointer
> and
> > accessed after that. No error has been done from
> my
> > side.
> 
> 
> It is 100% some logical error (bug). To avoid
> situations like this and
> have bullet proof code use the standard library
> containers instead of
> explicit memory allocation and deallocation.
> Examples can be seen below.

Logical error in my code or VC++ COmpiler??
> 
> #include <vector>
> 
> using namespace std;
> 
> 
> >  int *EleTopo=new int[seneles*sennds];
> 
> vector<int>EleTopo(seneles*sennds);
> 
> 
> >  char *NodeSign=new char[this->NNodes+1];
> 
> list, or vector, or string, or something...
> 
> 
> 
> > Similarly few other variables have been
> dynamically
> > allocated....
> > 
> >  for(int i=0;i<seneles;i++)
> >    for(int j=0;j<ncn;j++)
> >    {
> >      int cuEl = (theSubEle+ise)->SEtopo[i];
> > 
> >     
> *(EleTopo+i*ncn+j)=(theElement+cuEl-1)->topo[j];
> >      NodeSign[(theElement+cuEl-1)->topo[j]] =
> > 'P';//All nodes are marked as positive initially.
> >    }
> >  After this piece of code, 'EleTopo'  values are
> > printed and they confirmed to be correct.
> 
> 
> It is too messy! *(EleTopo+i*ncn+j)? What about the
> equivallent
> EleTopo[i*ncn+j] (which is somewhat messy too).
> Obviously you come from
> a hardcore C background and carry all that low stuff
> bagage. :)
Yes, it is equivalent to EleTopo[i][j] where are 'j'
ranges between 0 to ncn.
> 
> 
> 
> > 
> >  After few lines of other code.....
> > 
> >  for(int iel=seneles-1;iel>=0 ; iel--)
> >  {
> > 	int iLocalForEle=0;
> > 	int curElement = (theSubEle+ise)->SEtopo[iel];
> > 	if(iel==seneles-1)
> > 		coutf << "\n Final element in the SE
> is...:"<<iel;
> > //newAdd
> > 	int AnyNode;
> > 
> > 
> > 	int  noOfDf = 0;
> > 	NoOfNegNodes =0;
> > 	for(int j=0;j<ncn;j++)
> > 	{
> > 	   AnyNode = *(EleTopo+iel*ncn+j);
> > 	   int isThisNodeABN = 0;// is this a boundary
> node
> > of SE.
> > 	   for(int it=0;it<SeBNodes;it++)
> > 	   {
> > 	    	if(AnyNode ==
> > ((theSubEle+ise)->SEBounNodes[it]))
> > 		{
> > 			isThisNodeABN = 1;
> > 			break;
> > 		}
> > 		else
> > 		isThisNodeABN = 0;
> > 	   }
> > 
> > 	   if(isThisNodeABN==0)
> > 	   {
> > 
> > ******	   	if(NodeSign[*(EleTopo+iel*ncn+j)]=='N')
> > 	   	{
> > 			//Do nothing...
> > 	   	}
> > 	   	else
> > 	   	{
> > 			NodeSign[*(EleTopo+iel*ncn+j)]='N';
> > 			int nde = *(EleTopo+iel*ncn+j);
> > ******			*(EleTopo+iel*ncn+j) = 
> > -*(EleTopo+iel*ncn+j);
> > 			NoOfNegNodes++;
> > 
> > 			//saving the the dfs that are going to 
> > be removed
> > after this element being assembled.
> > 			for(int ir=0;ir<NDF;ir++)
> > 			{
> > 			  *(DfToRemove+iel*(ncn*NDF)+iLocalForEle)=
> > (nde-1)*NDF+ir;
> > 			  iLocalForEle++;
> > 			}
> > 			  noOfDf+=NDF;
> > 	   	}
> > 	   }
> > 	   else
> > 	      cout <<"\n this Node is a BoundaryNode of
> > SE...:"<<AnyNode<<".."<<ise;
> > 	}
> > 	noOfDf = iLocalForEle;
> > 	NoNegDf[iel]=NDF*NoOfNegNodes;
> >  }//sign check ends here.....
> 
> 
> 
> If any exception is thrown from somewhere there,
> much of all those
> allocated resources remain allocated.
> 
> 
> 
> > 
> > 
> >  The problem appears in the line marked with
> ******.
> > Actually this problem is seen only in some of the
> > problems. To give you more idea, I have tested
> this
> > code  as standalone, it worked fine for 'EleTopo'
> > sized upto 3200*6, then it worked  properly and no
> > memory violation was observed.
> > 
> >  But, when the code used as a server
> implementation in
> > CORBA environment, the  so called memory violation
> > took place when 'EleTopo' was sized to 800*6.
> Briefly,
> > 
> >  'EleTopo' is like an two dimentional array of
> size
> > [800][6]. I have to access  data in 'EleTopo' from
> the
> > end, ie., from [800][].
> 
> [799][].
yes, it is [799][]
> 
> 
> 
>  The values are correct till
> > [48][6] and started giving junk values for some of
> the
> > indexes between [47][] to [0][].
> > 
> >  I have shown in array form just for illustration
> > purpose.
> > 
> >  I am clueless how this memory violation is taking
> > place in some cases only.
> > 
> >  Will you pls suggest me what is going wrong in
> this.
> 
> 
> What is going wrong basically here is that you use
> C++ in the place of
> assembly programming. Deal C++ as a high level
> programming language and
> you can even gain some time/space! I suggest you
> read "The C++
> Programming Language" 3rd Edition or Special
> Edition. And be prepared
> for a life change. :)
Thank you.
> 
> 
> Ioannis
> 

regards,
Raghunath
=== message truncated ===


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