List Problem-Last entry overwriting all others

[kerrymaid]

Hi,

In the below program I have a list of structs(chordRing.chordNodeIDList). When an entry is added to the end of a list it is somehow overwriting one particular parameter (chordEntry->node_id) in every struct in the list. chordEntry->node_id is a 20 byte char array. I can't see why it would overwrite every entry- it has to be a memory error I assume but I'm stumped as to how to fix it.

Any help would be appreciated.

intersection_details= (ILS_Intersection_Trajectory_Vals*)op_prg_mem_alloc(sizeof(ILS_Intersection_Trajectory_Vals));
	intersectionCoordinates = (WsqT_Location_Message *) op_prg_mem_alloc (sizeof (WsqT_Location_Message));
		
	for (count = 0; count < sizeOfIntersectionList; count++)
	{
		
		intersection_details = (ILS_Intersection_Trajectory_Vals*) op_prg_list_access (intersection_ptr->intersection_list, count);
		
		//If the Chord ring doesn't exist, this will create a list and add the node ID to it
		if (chordRing.chordNodeIDList == OPC_NIL)
		{
			chordEntry = (DhtT_Chord_Entry*) op_prg_mem_alloc(sizeof(DhtT_Chord_Entry));
			
			chordEntry->ip_addr = intersection_details->int_ip;
			
			if (cantor_sfc == OPC_TRUE)
			{
				intID = Algorithm_Cantor_XY_to_N (intersection_details->x_pos, intersection_details->y_pos);

				//tmp_num = intID/20;			
				
				dblNodeID = (double)intID;
				dbl_tmp_num = dblNodeID/20.0;
				tmp_num = ceil(dbl_tmp_num);				
				
				for (i=0; i<=19;i++)
				{	
					tmp [i]=(char)tmp_num;
					if(i== 19)
					{
						possible_difference = intID - (tmp_num * 19);
						tmp[i] = (char)possible_difference;
					}
				}
				
				temporary = (DhtT_Key_Bytes) op_prg_mem_alloc(20);
				 temporary = (DhtT_Key_Bytes)tmp;
				chordEntry->node_id = temporary;
				
				}
			else
			{
				chordEntry->node_id = dht_get_node_id(intersection_details->int_ip);
			}			
			
			chordEntry->x_pos = intersection_details->x_pos;
			chordEntry->y_pos = intersection_details->y_pos;
			
			intID = sha_get_int_id(chordEntry->node_id);
			printf ("\nInt id: %lf",intID);

			//global_chord_ring is a static instance of a List
			chordRing.chordNodeIDList = op_prg_list_create();
				
			//insert the node ID as the first and only entry currently in the list.
			//op_prg_list_insert(chordRing.chordNodeIDList, *myNodeID, OPC_LISTPOS_HEAD);
				
			//new
			op_prg_list_insert(chordRing.chordNodeIDList, chordEntry, OPC_LISTPOS_HEAD);
			
			printChordRing();
					
			if ((op_prg_odb_ltrace_active ("trace_chord") == OPC_TRUE))
			{
				printf("\nCreating Chord Ring for the first time");
			}
			}
		else //The Chord Ring does exist so just insert my Node ID in a sorted position
		{
			//Insert the current entry into sorted position.  The list is sorted from lowest to highest
			//  DHT ID, like a Chord ring that is broken and stretched into a line. 
	
			chordEntry = (DhtT_Chord_Entry*) op_prg_mem_alloc(sizeof(DhtT_Chord_Entry));
			
			chordEntry->ip_addr = intersection_details->int_ip;
			
			if (cantor_sfc == OPC_TRUE)
			{
				intID = Algorithm_Cantor_XY_to_N (intersection_details->x_pos, intersection_details->y_pos);

				tmp_num = intID/20;
				for (i=0; i<=19;i++)
				{	
					tmp [i]=(char)tmp_num;
					if(i== 19)
					{
						possible_difference = intID - (tmp_num * 19);
						if (possible_difference > tmp_num)
							tmp[i] = (char)possible_difference;
					}
				}
				
				 temporary = (DhtT_Key_Bytes) op_prg_mem_alloc(20);
				 temporary = (DhtT_Key_Bytes)tmp;
				chordEntry->node_id = temporary;
			}
			else
			{
				chordEntry->node_id = dht_get_node_id(intersection_details->int_ip);
			}
			
			intnodeID = sha_get_int_id(chordEntry->node_id);
			chordEntry->x_pos = intersection_details->x_pos;
			chordEntry->y_pos = intersection_details->y_pos;
			
			printf ("\nInt id: %lf",intnodeID);
			
			op_prg_list_insert_sorted(chordRing.chordNodeIDList, chordEntry, dht_sup_chord_ring_entry_compare);
			//op_prg_list_insert(chordRing.chordNodeIDList, chordEntry, OPC_LISTPOS_TAIL);
			
			printChordRing();
	}
	}
	
	printChordRing();

[TheBigH]

You can't say "array1 = array2" and expect all the elements to be copied automagically. What it actually does it set the address of array1 to be the address of array2. So when you set a whole bunch of node_id's to be equal to "temporary", you are making them all point to the same location in memory. That's why it looks like they're being overwritten.

To copy one string into another, use strcpy.

[kerrymaid]

Thanks, I used memcpy() and it solved it.