下列给定程序中，函数fun的功能是：统计带头结点的单向链表中结点的个数，并存放在形参n所指的存储单元中。 请在程序的下画线处填入正确的内容并将下画线删除，使程序得出正确的结果。 试题程序： #define N 8 typedef struct list {     int data;     struct list *next; } SLIST; SLIST *creatlist (int *a); void outlist(SLIST *); void fun (SLIST *h, int *n) {     SLTST *p;     1 = 0;     p = h -> next;     while (p)     {         (* n ) ++;         p = p -> 2 ;     } } main ( ) {     SLIST *head ;     int a [ N ] = {12 , 87 , 45 , 32 , 91 , 16 , 20, 48}, num;     head = creatlist (a);     outlist (head);     fun( 3 , & num);     printf ( " \ nnumber = d \ n ", num); } SLIST *creatlist (int a []) {     SLTST *h , * p , * q ;    int i;     h = p = (SLIST *) malloc(sizeof(SLIST));     for ( i = 0 ; i < N ; i + + )     {         q = ( SLIST *) malloc ( sizeof ( SLIST ) );         q -> data = a [ i ] ;         p -> next = q ;         p = q ;     }     p - > next = 0 ;     return h; } void outlist ( SLIST *h ) {     SLIST    *P ;     p = h -> next ;     if  (p == NULL )         printf ( "The list is NULL ! \ n ");     else     {         printf ( "\nHead " );         do         {             printf ( " -> % d", p -> data );             p = p->next ;         }         while ( p != NULL );         printf ( " -> End \ n ");     } }