有关了链表的实现，请大家帮忙看一下,该如何解决

有关了链表的实现，请大家帮忙看一下
#ifndef   _List_H

struct   Node;
typedef   struct   Node   *PtrToNode;
typedef   PtrToNode   List;
typedef   PtrToNode   Position;

List   MakeEmpty(List   L);
int   IsEmpty(List   L);
int   IsLast(List   L);
Position   Find(int   X,List   L);
void   Delete(int   X,List   L);
Position   FindPrevious(int   X,List   L);
void   DeleteList(List   L);
Position   Header(List   L);
Position   First(List   L);
Position   Advance(Position   P);
int   Retrieve(Position   P);

#endif

struct   Node  
{
  int   Element;
  Position   Next;
};

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


void   main()
{
Position   Insert(int   X,List   L,Position   P);
int   PrintList(List   L);
Position   P,L,Head;
int   C;
Head=(Position)malloc(sizeof(struct   Node));
Head-> Next   =NULL;
L=Head;
P=L;
        while((C=getchar())!=EOF)
        {
          Insert(C,L,P);
        }
        PrintList(Head);
}


//return   true   if   L   is   empty
int   IsEmpty(List   L)
{
return   L-> Next==NULL;
}

//return   true   if   P   is   thr   last   position   in   list   L

int   IsLast(Position   P,List   L)
{
return   P-> Next==NULL;
}

//return   position   of   X   in   L;NULL   if   not   found

Position   Find(int   X,List   L)
{
Position   P;
P=L-> Next;
while(P!=NULL&&P-> Element!=X)
P=P-> Next;
return   P;
}


//delete   first   occurrence   of   X   from   a   list
//assume   use   of   a   header   node

void   Delete(int   X,List   L)
{
Position   P,TmpCell;
P=FindPrevious(X,L);

if(!IsLast(P,L))
{
TmpCell=P-> Next;
P-> Next=TmpCell-> Next;
free(TmpCell);
}
}


//if   X   is   not   found   ,then   next   field   of   returned
//postion   is   NULL
//assumes   a   header

Position   FindPrevious(int   X,List   L)
{
Position   P;

P=L;
while(P-> Next!=NULL&&P-> Next-> Element!=X)
P=P-> Next;
return   P;
}


//insert   (after   legal   position   P)
//header   implementation   assued
//parameter   L   is   unused   in   this   implementation

void   Insert(int   X,List   L,Position   P)
{
Position   TmpCell;
TmpCell=(Position)malloc(sizeof(struct   Node));
if(TmpCell==NULL)
printf( "out   of   space!!!!! ");
TmpCell-> Element=X;
TmpCell-> Next=P-> Next;
P-> Next=TmpCell;
}


//delete   all   list

void   DeleteList(List   L)
{
Position   P,Tmp;
P=L-> Next;
L-> Next=NULL;
while(P!=NULL)
{
Tmp=P-> Next;
free(P);
P=Tmp;
}
}


//print   a   list  
//header   implementtation   assued

void     PrintList(List   Head)
{
Position   P;
P=Head;
if(P!=NULL)
do
{
printf( "%d ",P-> Element);
P=P-> Next;
                }while(P!=NULL);

}


[解决办法]
定义，声明形式不一致