프로그래밍 중 자료구조에 관하여 질문드립니다.

-main함수

1. #include <stdio.h>

2. #include "Com_In_head.h"

3. int main(void)

4. {

5. List plist;

6. ListInit(&plist);

7. Linsert(&plist, 154998, "kim");

8. Linsert(&plist, 141850, "jin");

9. Linsert(&plist, 176236, "park");

10. Linsert(&plist, 187649, "harry");

11. return 0;

12. }

-헤더파일

1. #ifndef __Com_In_Head__

2. #define __Com_In_head__

3. typedef struct ComH

4. {

5. int Hnum;

6. char *Hname;

7. }ComH;

8. typedef struct _node

9. {

10. ComH *data;

11. struct _node * next;

12. }Node;

13. typedef struct _Cll

14. {

15. Node *tail;

16. Node *cur;

17. Node *before;

18. int numOfData;

19. }List;

20. void ListInit(List *plist);

21. void Linsert(List *plist, int Hnum,char *Hname);

22. /*int Lfirst(List *plist, int *pdata);

23. int Lnext(List *plist, int *pdata);

24. int Lremove(List *plist);

25. int Lcount(List *plist);*/

26. #endif

-헤더파일에 선언된 함수코드

1. #include <stdio.h>

2. #include "Com_In_Head.h"

3. void ListInit(List *plist)

4. {

5. plist->tail = NULL;

6. plist->cur = NULL;

7. plist->before = NULL;

8. plist->numOfData = 0;

9. }

10. void Linsert(List *plist, int HNum, char *HName)

11. {

12. Node *newnode = (Node*)malloc(sizeof(Node));

13. newnode->data->Hnum = HNum;

14. newnode->data->Hname = HName;

15. if (plist->tail == NULL)

16. {

17. plist->tail = newnode;

18. newnode->next = newnode;

19. }

20. else

21. {

22. plist->tail->next = newnode;

23. newnode->next = plist->tail->next;

24. plist->tail = newnode;

25. }

26. plist->numOfData++;

27. }

보기가 명확하지는 않은데요!

Linsert함수에서

newnode->data->Hnum = HNum; newnode->data->Hname = HName;

이 코드가 쓰기 엑세스 위반이라고 뜨는데 이유가 뭔가요?