연결리스트에 대한 질문입니다...

 
typedef struct _user
{
        char u_name[20];
        struct _user *u_next;
}user;
user *u_head, *u_tail;
 
typedef struct _channel
{
        int user_count;
        char channel_name[20];
        struct _channel *c_next;
        struct _user *user;
}channel;
channel *c_head, *c_tail;
 
void init_user(void)
{
        u_head=(user*)malloc(sizeof(user));
        u_tail=(user*)malloc(sizeof(user));
        u_head->u_next=u_tail;
        u_tail->u_next=u_tail;
}
void init_channel(void)
{
        c_head=(channel*)malloc(sizeof(channel));
        c_tail=(channel*)malloc(sizeof(channel));
        c_head->c_next=c_tail;
        c_tail->c_next=c_tail;
}
 
 
//문자열을 받아와서 채널생성
 
void create_channel(char *s)
{
        printf("새로운 채널 생성했습니다\n");
        channel *t;
        t=(channel*)malloc(sizeof(channel));
        strcpy(t->channel_name,s);
        t->c_next=c_head->c_next;
        c_head->c_next=t;
        t->user_count=0;
}
 
 
//유저와 채널이름을 받아서 실행하는 함수
 
//같은 채널이라면 그 채널안의 구조체에 연결된 유저이름에 저장
 
void have_channel(char *ur_name,char *cl_name)
{
        user *t;
        channel *p;
        p=(channel*)malloc(sizeof(channel));
        p=c_head->c_next;
        p->user=(user*)malloc(sizeof(user));
 
        while(strcmp(cl_name,p->channel_name) !=0 && p!=c_tail)
        {
                p=p->c_next;
        }
        p->user_count++;
        strcpy(p->user->u_name,ur_name);
        p->user->u_next=u_head->u_next;
        u_head->u_next=p->user;
}
 
 
//채널정보검색
 
        printf("정보를 알고 싶은 채널 : \n");
        fgets(buf,20,stdin);
        buf[(strlen(buf)-1)]='\0';
        channel *p;
        user *t;
        p=c_head->c_next;
        p->user=u_head->u_next;
        while(strcmp(buf,p->channel_name) !=0 && p!=c_tail)
        {
                  p=p->c_next;
        }
        if(p==c_tail)
        {
         printf("찾으시는 채널이 없습니다\n");
         return 1;
        }
        while(p->user_count--)
 
         {
         printf("%s\n",p->user->u_name);
         p->user=p->user->u_next;
        }