The declaration of the function and the signature of the defined function are different, so it is strange to succeed. . .

Status InitList_L(LinkList,ElemType *);//创建带头节点的单链表         -- 这是你的声明
Status InitList_L(LinkList &L,ElemType *ptr) // !!! 第一个参数不同   -- 定义却是这样的

Please try changing fun.cpp to declare.cpp

The function declared in your declara.h has a different signature than the function you implemented in fun.cpp, and it will definitely fail

//declar.h
Status InitList_L(LinkList,ElemType *);//创建带头节点的单链表
Status ListInsert_L(LinkList,int,ElemType);//在链表元素i前插入元素e
Status ListDelete_L(LinkList,int,ElemType);//删除第i个节点，用e带回
ElemType FindData_L(LinkList,ElemType);//查找元素n
void MergeList_L(LinkList,LinkList);//合并两个链表
void ListTraver_L(LinkList);//打印链表元素
void InputList_L(ElemType *);//输入数据

//declar.h
//修改之后
Status InitList_L(LinkList &, ElemType *);//创建带头节点的单链表
Status ListInsert_L(LinkList &, int, ElemType);//在链表元素i前插入元素e
Status ListDelete_L(LinkList &, int, ElemType &);//删除第i个节点，用e带回
ElemType FindData_L(LinkList, ElemType);//查找元素n
void MergeList_L(LinkList &, LinkList &);//合并两个链表
void ListTraver_L(LinkList);//打印链表元素
void InputList_L(ElemType *);//输入数据