下列给定,函数fun的功能是:在带头结点的单向中,查找数据域中值为ch的结点。找到后通过函数值返回该结点在中所处的顺序号;若不存在值为ch的结点,函数返回0值。 #include #include #define N 8 typedef struct list { int data; struct list *next; } SLIST; SLIST *creatlist(char *); void outlist(SLIST *); int fun( SLIST *h, char ch) { SLIST *p; int n=0; p=h->next; /**********found**********/ while(p!=______) { n++; if (p->data==ch) return n; else p=p->next; } return 0; } main() { SLIST *head; int k; char ch; char a[N]={'m','p','g','a','w','x','r','d'}; head=creatlist(a); outlist(head); printf("Enter a letter:"); scanf("%c",&ch); k=fun( head,ch); if (k==0) printf("\nNot found!\n"); else printf("The sequence number is : %d\n",k); } SLIST *creatlist(char *a) { SLIST *h,*p,*q; int i; h=p=(SLIST *)malloc(sizeof(SLIST)); for(i=0; i 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("\nThe list is NULL!\n"); else { printf("\nHead"); do { printf("->%c",p->data); p=p->next; } while(p!=NULL); printf("->End\n"); } } A. B. NuLL C. NULL D. Null