singly linked list - Link another structure in C -

i trying data stucture in c. connect structure structure. this:

struct room {  int roomnumber;  struct room * nextroom;  struct person * personlist; }*top=null,*temp=null,top1;  struct person {  int personnumber;  struct person *next; }*node=null,temp1; 

struct room has pointer struct person. having hard time on connecting struct. correct?

here function

void insert() {     int val;     printf("enter value: ");     scanf("%d",&val);     newnode=create_node(val);     if(top->personlist==null)     {         top->personlist=newnode;     }     else     {         node->next=newnode;         node=newnode;       } } 

insert person room. room created already. create_node() 1 malloc()

here's version doesn't use globals, makes functions more general , reusable:

#include <stddef.h> #include <stdlib.h> #include <stdio.h>  typedef struct person {   int            personnumber;    struct person *next;  } person;  /* note: typedef, not global declaration did */  typedef struct room {   int          roomnumber;   person      *personlist;   person      *lastinlist;    struct room *nextroom;  } room;  /* note: typedef, not global declaration did */  person *create_person(int val) {   person *ret = calloc(1, sizeof(*ret));    if (ret)   {     ret->personnumber = val;     ret->next         = null;   }    return ret; }  int room_insert(room *r, int val) {   person *p = create_person(val);    if (null == p)     return -1;    if (null != r->personlist)     r->lastinlist->next = p;    else     r->personlist = p;    r->lastinlist = p;    return 0; }  int main(int argc, char **argv) {   room    my_room       = { 0 };  /* important! initializes pointers null */   room    my_other_room = { 0 };  /* important! initializes pointers null */   person *p;    room_insert(&my_room, 5);   room_insert(&my_other_room, -5);    room_insert(&my_room, 10);   room_insert(&my_other_room, -10);    room_insert(&my_room, 15);       room_insert(&my_other_room, -15);    (p = my_room.personlist; p; p = p->next)     printf("%d\n", p->personnumber);    (p = my_other_room.personlist; p; p = p->next)     printf("%d\n", p->personnumber);    return 0; }