Thread: HELP!!! Memory allocation error!

im getting the following message: "error for object 0x3fd6a7ef: pointer being reallocated was not allocated". It's got something to do with the way i am allocating memory to the pointer "acceptors." The strange thing is that even if I allocate the memory statically ( e.g. ACCEPTORS acceptors[50]) I still get an error message.

I have previously defined ACCEPTORS as:

Code:

typedef struct
{
  int index;
  double da_r;
  double theta;
}
ACCEPTORS;

All the user-defined functions within this function work perfectly fine, the problem that I'm having is with memory allocation. Any help and suggestions would be greatly appreciated.

Here's the function:

Code:

double checkforhbonds(MOLECULE molecule1,int i,MOLECULE molecule2)
{
  double dhb;
  double ijlength,minlength,alength,dhlength,E_hb,jlength,ialength;
  int j,minj,donor,atj,num_acc,a;
  ACCEPTORS *acceptors;

  minlength=100000; //fix this
  num_acc=0;

  dhb = dveclength(molecule1.atom[i].cart); //magnitude of h atom vector

  for(j=0;j<molecule1.numatoms;j++)
    {
      if(j!=i)
	{
	  jlength=dveclength(molecule1.atom[j].cart); //magnitude of test donor
	  ijlength=fabs(dhb-jlength); //distance between h-atom and test donor
	  if(ijlength<minlength)
	    {
	      minlength=ijlength;
	      donor=j;
	    }
	}
    }
  dhlength=dhb-minlength;//length betwen h atom and donor
  for(atj=0,num_acc=0;atj<molecule2.numatoms;atj++)
    {
      alength=dveclength(molecule2.atom[atj].cart);//magnitude of test acceptor vector
      ialength=fabs(dveclength(molecule1.atom[donor].cart)-alength); //distance between donor and prospective acceptor 
	if((ialength)<HBONDTHRESHOLD)
	  {
	    acceptors=realloc(acceptors,(num_acc+1)*sizeof(ACCEPTORS));
	    dhlength=dhb-minlength;
	    acceptors[num_acc].index=atj;//index number in molecule of acceptor
	    acceptors[num_acc].da_r=ialength; //Rda               difference between acceptor and h                           difference between donor and h
	    acceptors[num_acc].theta=dvecangle(dvecsubtr(molecule2.atom[atj].cart,molecule1.atom[i].cart),dvecsubtr(molecule1.atom[donor].cart,molecule1.atom[i].cart)); //theta
	    num_acc++;
	  }
    }
  if(num_acc>0)
    {
     for(a=0;a<=num_acc;a++)
       {
	 E_hb=E_hb+Ehbonds(acceptors[a].da_r,acceptors[a].theta);
       }
    }
    free(acceptors);
  return(E_hb);
}

thank you.

PLEASE, USE CODE TAGS around your code!


Edit:
I am no expert on malloc, but I don't think you can realloc something that was never malloc'd or calloc'd in the first place.

Might I add that you should pick a topic name that doesn't sound like your nuclear reactor just melted down.... It only serves to make light of the cases that are indeed urgent.

it should be better now, please help.

Do you have javascript turned off - because posts with braces in are not normally allowed.
You're supposed to have gotten a prompt to tell you to use [code][/code] tags.

Post edited - just this once.

> im getting the following message: "error for object 0x3fd6a7ef: pointer being reallocated was not allocated"
Start with
ACCEPTORS *acceptors = NULL;
If you want realloc to behave like malloc on the first call.

Also, do a board search on the safe way to call realloc, which doesn't leak memory if it fails.


> for(a=0;a<=num_acc;a++)
This looks like a buffer overflow. The normal loop is for < N, not <= N