Thread: Passing a linked list to a function

I am trying to pass a pointer to a linked list to a function. I want the function to modify the linked list.
In the function, If I print out a member of the structure,it works,but if I try to print in main the program breaks,which leads me to think it has something to do with bad pointers.
Here's the code:

Code:

typedef struct 
{
    int total;
    int paid;
    Item *items_ordered; 

}Meal;

Code:

typedef struct group Group,*Pgroup;

struct group
{
    int n_elements;
    int served;
    Meal *request_meal;
    Pgroup next;

};

Code:

void main()
{
    ...
    Pgroup list_group=NULL;
    int n_groups;
    Table *table=NULL;
    Group *group=NULL;
    int n_tables=12;

                            n_groups=register_group(&group,&table,n_tables,n_groups,&list_group);
                            printf("%d\n",list_group->n_elements);//breaks
                            ...

    free(group);
 
}

Code:

int register_group(Group **group,Table **table,int capacity,int n_groups,Pgroup *list)
{
    int i,num_p;

    n_groups++;
    *group=(Group *) realloc(*group,n_groups*sizeof(Group));

    printf("Type the number of epople in the group:\n");
    scanf("%d",&num_p);
    

    for(i=0;i<capacity;i++)
    {
        printf("%d %d\n",(*table)[i].free,(*table)[i].capacity);
        if((*table)[i].livre && (*table)[i].capacity==num_p)
        {
            
            (*table)[i].suc_groups=group[n_groups-1];
            (*table)[i].free=FALSE;
            (*group)[n_groups-1].n_elements=num_p;
            (*group)[n_grups-1].served=FALSE;
            (*group)[n_groups-1].next=NULL;
            (*group)[n_groups-1].request_meal=NULL;
            return n_groups;
        }
        
    }
        printf("No tables available for that number of people!\n");
        printf("Adding to the queue...\n");
        add_group_list(list,num_p);
                
        
    return n_groups;
}

Code:

void add_group_list(Pgroup *ptr_list,int n_people)
{
    Pgroupo new,aux;

    new=(Group*)malloc(sizeof(Group));

    if(new == NULL)
    {
        printf("Error alocating memory\n");
        exit(1);
    }

    if((*ptr_list)==NULL)
    {
        new->n_elements=n_people;
        new->served=FALSE;
        new->request_meal=NULL;
        new->nex=*(ptr_list);
        (*ptr_list)=new;
    }
    else
    {
        aux=(*ptr_list);
        while(aux->next!=NULL)
            aux=aux->next;
        aux->next=new;
    }
  

}

The problem is you are not initializing 'new' members.

Code:

    
     if((*ptr_list)==NULL)
    {
        new->n_elements=n_people;
        new->served=FALSE;
        new->request_meal=NULL;
        new->nex=*(ptr_list);
        (*ptr_list)=new;
    }
    else
    {
        aux=(*ptr_list);
        while(aux->next!=NULL)
            aux=aux->next;
        aux->next=new;                // new members are not initialized properly 
    }