【数据结构】【链表】【不带头结点】【纯C代码实现】

list.h

#include <stdio.h>
#include <stdlib.h>

#define ERROR NULL
typedef int ElementType;
typedef struct LNode *PtrToLNode;
struct LNode {
    ElementType Data;
    PtrToLNode Next;
};
typedef PtrToLNode Position;
typedef PtrToLNode List;

Position Find( List L, ElementType X );
List Insert( List L, ElementType X, Position P );
List Delete( List L, Position P );

list.c

Position Find( List L, ElementType X ){
    while(L){
        if(L->Data == X) {
            return L;
        }
        L = L->Next;
    }
  return ERROR;


}
List Insert( List L, ElementType X, Position P ){
    List LNode = L;
    List tmp = (List) malloc(sizeof (struct LNode));
    tmp->Data = X;
    if(L == P){//如果P是头结点
        tmp ->Next = L;
        return tmp;
    }
    while (L){//p不是头结点
        if(L->Next == P){
            L->Next = tmp;
            tmp->Next = L->Next->Next;
            return LNode;
        }
        L = L->Next;
    }
    printf("Wrong Position for Insertion\n");
    return ERROR;
}
List Delete( List L, Position P ){
    List LNode = L;
    if(P == L)//如果P是头结点
    {
         L = L->Next;
         free(LNode);
         return L;
    }
    while (L){
        if(L->Next == P ){
            List tmp = P;
            L->Next = L->Next->Next;
            free(tmp);
            return LNode;
        }
            L = L->Next;
    }
    printf("Wrong Position for Deletion\n");
    return ERROR;
}