带头结点的链式表操作集

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

#define ERROR NULL
typedef enum {false, true} bool;
typedef int ElementType;
typedef struct LNode *PtrToLNode;
struct LNode {
ElementType Data;
PtrToLNode Next;
};
typedef PtrToLNode Position;
typedef PtrToLNode List;

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

int main()
{
List L;
ElementType X;
Position P;
int N;
bool flag;

L = MakeEmpty();
scanf("%d", &N);
while ( N-- ) {
scanf("%d", &X);
flag = Insert(L, X, L->Next);
if ( flag==false ) printf("Wrong Answer\n");
}
scanf("%d", &N);
while ( N-- ) {
scanf("%d", &X);
P = Find(L, X);
if ( P == ERROR )
printf("Finding Error: %d is not in.\n", X);
else {
flag = Delete(L, P);
printf("%d is found and deleted.\n", X);
if ( flag==false )
printf("Wrong Answer.\n");
}
}
flag = Insert(L, X, NULL);
if ( flag==false ) printf("Wrong Answer\n");
else
printf("%d is inserted as the last element.\n", X);
P = (Position)malloc(sizeof(struct LNode));
flag = Insert(L, X, P);
if ( flag==true ) printf("Wrong Answer\n");
flag = Delete(L, P);
if ( flag==true ) printf("Wrong Answer\n");
for ( P=L->Next; P; P = P->Next ) printf("%d ", P->Data);
return 0;
}
List MakeEmpty(){  //创建并返回一个空的线性表；
List head=(List)malloc(sizeof(struct LNode));
head->Next=NULL;
return head;
}
Position Find( List L, ElementType X ){//返回线性表中X的位置。若找不到则返回ERROR；
while(L){
if(L->Data==X){
return L;
break;
}
L=L->Next;
}
return ERROR;
}
/*
将X插入在位置P指向的结点之前，返回true。
如果参数P指向非法位置，
则打印“Wrong Position for Insertion”，
返回false；
*/
bool Insert( List L, ElementType X, Position P ){
if(L==P){
L=(List)malloc(sizeof(struct LNode));
L->Data=X;
L->Next=P;
return true;
}
while(L){
if(L->Next==P) break;
L=L->Next;
}
if(!L){
printf("Wrong Position for Insertion\n");
return false;
}
L->Next=(List)malloc(sizeof(struct LNode));
L->Next->Data=X;
L->Next->Next=P;
return true;
}
/*
将位置P的元素删除并返回true。
若参数P指向非法位置，
则打印“Wrong Position for Deletion”
并返回false。
*/
bool Delete( List L, Position P ){
if(L->Next==P){
L->Next=P->Next;
return true;
}
while(L){
if(L->Next==P) break;
L=L->Next;
}
if(!L){
printf("Wrong Position for Deletion\n");
return false;
}
L->Next=P->Next;
return true;
}