fatal error LNK1169: one or more multiply defined symbols found

最近开始做数据结构方面的编程，简单的问题，却出现LINK方面的问题。
如果把main()里面的code放到LinkList.cpp里面去的话，编译是没问题的。
但是单独拿出来，再编译的话，就会出现fatal error LNK1169: one or more multiply defined symbols found

特来请教高人，先答出者，马上送20分。

//LinkList.h文件：

typedef int ElemType;
#define OK 1

//Á´±í½Óµã½á¹¹Ì嶨Òå [data *next]
// --------------
// |data | *next|
// --------------
typedef struct LNode
{
ElemType data;
struct LNode *next;
}LNode, *pLinkList;

//Á´±íÀà½Ó¿Ú¶¨Òå
class LinkList
{
public:
LinkList();
~LinkList();
bool InitList();
bool DestroyList();
bool ClearList();
bool IsEmpty();
int GetLength();

int LocateElem(int elem);

bool SetNodeData(int position, ElemType newData);
bool GetNodeData(int position, ElemType &data);
bool GetNode(int position, LNode **node);

bool InsertNode(int beforeWhich, ElemType data);
bool DeleteNode(int position);
private:
pLinkList m_pList;
int m_length;
};



//LinkList.cpp
#include <iostream.h>
#include "LinkList.h"

LinkList::LinkList()
{
m_pList=NULL;
m_length=0;
}

//Ïú»ÙÁ´±í
bool LinkList::DestroyList()
{
if(!ClearList())
{
return false;
}

delete m_pList;

return true;
}

LinkList::~LinkList()
{
if(!DestroyList())
{
DestroyList();
}
}


//½«LÖØÖÃΪ¿Õ±í£¬Ç°ÌáÊÇÏßÐÔ±íLÒÑ´æÔÚ
bool LinkList::ClearList()
{
if (m_pList==NULL)
{
return false;
}

LNode *pTemp=NULL;
while(m_pList->next!=NULL)
{
pTemp=m_pList->next;//pTempÖ¸ÏòµÚÒ»¸ö½Úµã
m_pList->next=pTemp->next;
delete pTemp;
}

m_pList->next=NULL;
m_length=0;

return OK;
}


//³õʼ»¯£¬·ÖÅäÒ»¸öÍ·½Úµã
bool LinkList::InitList()
{
m_pList=new LNode;
if(m_pList==NULL)
return false;

m_pList->next=NULL;

return true;
}

//ÅжÏÁ´±íÊÇ·ñΪ¿Õ£¬ÊÇ¿ÕÔò·µ»Øtrue£¬·ñÔò·µ»Øfalse
bool LinkList::IsEmpty()
{
if(m_pList->next==NULL)
{
return true;
}
else
{
return false;
}
}

//·µ»ØÁ´±íÖе±Ç°½ÚµãÊý
int LinkList::GetLength()
{
return m_length;
}

//½«positionÖ¸¶¨µÄ½ÚµãÄÚµÄÊý¾ÝÉèÖÃΪnewData
//µÚ1¸öÓÐЧ½ÚµãµÄpostionΪ1
bool LinkList::SetNodeData(int position, ElemType newData)
{
LNode *pTemp=NULL;

if(!(GetNode(position,&pTemp)))
{
return false;
}

pTemp->data=newData;

return true;
}

//µÃµ½Ö¸¶¨Î»ÖýڵãµÄÖ¸Õë
bool LinkList::GetNode(int position, LNode **node)
{
LNode *pTemp=m_pList;
int curPos=0;

if (position<1 || position>m_length)
{
return false;
}

while (pTemp!=NULL)
{
curPos++;
if(curPos==position)
break;
pTemp=pTemp->next;
}

if(curPos!=position)
{
return false;
}

*node=pTemp;

return true;
}

//»ñÈ¡position´¦µÄdata
bool LinkList::GetNodeData(int position, ElemType &data)
{
LNode *pTemp=m_pList;
int curPos=0;

if(position<1 || position>m_length)
return false;

while(pTemp!=NULL)
{
if(curPos==position)
break;
pTemp=pTemp->next;
}

if(curPos!=position)
{
return false;
}

data=pTemp->data;

return true;
}

//ÔÚÁ´±íÖвåÈëÒ»¸ö½Úµã
//нڵã²åÈëÔÚbeforeWhich֮ǰ
//beforeWhichÈ¡ÖµÔÚ(1,length+1)Ö®¼ä
bool LinkList::InsertNode(int beforeWhich, ElemType data)
{
LNode *pTemp=NULL;

if(beforeWhich<1 ||beforeWhich>m_length+1)
{
return false;
}

if(!(GetNode(beforeWhich-1, &pTemp)))
{
return false;
}

LNode *newNode=new LNode;
newNode->data=data;
newNode->next=pTemp->next;

pTemp->next=newNode;

m_length++;

return true;
}


//main()函数：
#include <iostream.h>
#include "LinkList.cpp"

int main()
{
LinkList p;
p.InitList();
p.InsertNode(1,100);

return 1;
}