fscanf question - invalid memory access error

Hi,

I think this is a pretty basic problem but I'm still stumped as to why it's happening:

I use the following code (making use of a simulator API) to read in from a file and store information in a list (the format of the information is an id number (int) followed by an x and y co-ordinate (both doubles)).

My code reads everything in fine until I get to an id number that has double digits e.g. 10 at which point it gives me an "invalid memory access" error. If I edit the file to only have entries up until id number 9, it works fine. I cannot understand why this would be the case. It fails on the fscanf line for the file entry with an id number of 10.

Any help appreciated.

Code:

        fscanf(intersectionPositions_traj_file, "%d %lf %lf",&int_id,&x_pos,&y_pos);//read the values from file
        
        while(!feof(intersectionPositions_traj_file))
        {                
                //create a new instance of the struct to hold the data. this will be added to the list
                int_measurement= (ILS_Intersection_Trajectory_Vals*)op_prg_mem_alloc(sizeof(ILS_Intersection_Trajectory_Vals));
                int_measurement->int_id=int_id;
                                                                
                int_measurement->x_pos=x_pos;
                int_measurement->y_pos=y_pos;
                
                sprintf(stringIP, "%d.%d.%d.%d", int_id, int_id, int_id, int_id);

                intersectionInetTAddress.address.ipv4_addr = *stringIP;
                int_measurement->int_ip = inet_ipv4_address_get(intersectionInetTAddress);

                op_prg_list_insert(intersection_ptr->intersection_list,int_measurement,OPC_LISTPOS_TAIL);
                printf("values added to the INTERSECTION list.\n %d\t%lf\t%lf\n",int_measurement->int_id,int_measurement->x_pos,int_measurement->y_pos);
                
                fscanf(intersectionPositions_traj_file, "%d %lf %lf",&int_id,&x_pos,&y_pos);//read the values from file
        }