求助连接错误error LNK2001: unresolved external symbol "long __stdcall Wn

#include<windows.h>
#include<string.h>
#include<stdlib.h>
#include<stdio.h>int nMode;
LRESULT CALLBACK WndProc(HWND,UINT,WPARAM,LPARAM);
int WINAPI WinMain(HINSTANCE hInstance,HINSTANCE hPrevInst,LPSTR lpszCmdLine,int nCmdShow)
{
HWND hwnd;
MSG Msg;
WNDCLASS wndclass;
char lpszClassName[]="映射模式";
char lpszTitle[]="My_Map_Mode";
wndclass.style=0;
wndclass.lpfnWndProc=WndProc;
wndclass.cbClsExtra=0;
wndclass.cbWndExtra=0;
wndclass.hInstance=hInstance;
wndclass.hIcon=LoadIcon(NULL,IDI_APPLICATION);
wndclass.hCursor=LoadCursor(NULL,IDC_ARROW);
wndclass.hbrBackground=(HBRUSH)GetStockObject(WHITE_BRUSH);
wndclass.lpszMenuName=NULL;
wndclass.lpszClassName=lpszClassName;
if (!RegisterClass(&wndclass))
{
MessageBeep(0);
return FALSE;
}
hwnd=CreateWindow(lpszClassName,lpszTitle,WS_OVERLAPPEDWINDOW,CW_USEDEFAULT,CW_USEDEFAULT,CW_USEDEFAULT,CW_USEDEFAULT,NULL,NULL,hInstance,NULL);
ShowWindow(hwnd,nCmdShow);
UpdateWindow(hwnd);
while (GetMessage(&Msg,NULL,0,0))
{
TranslateMessage(&Msg);
DispatchMessage(&Msg);
}
return Msg.wParam;
}
LRESULT CALLBACK WndPorc(HWND hwnd,UINT message,WPARAM wParam,LPARAM lParam)
{
HDC hdc;
PAINTSTRUCT ps;
HBRUSH hB1,hB2;
switch (message)
{
case WM_LBUTTONDOWN:
nMode=MM_ISOTROPIC;
InvalidateRect(hwnd,NULL,1);
break;
case WM_RBUTTONDOWN:
nMode=MM_ANISOTROPIC;
InvalidateRect(hwnd,NULL,1);
break;
case WM_PAINT:
hdc=BeginPaint(hwnd,&ps);
SetMapMode(hdc,nMode);
SetWindowExtEx(hdc,150,150,NULL);
SetViewportExtEx(hdc,150,100,NULL);
SetViewportOrgEx(hdc,150,60,NULL);
hB1=(HBRUSH)GetStockObject(WHITE_BRUSH);
hB2=(HBRUSH)GetStockObject(BLACK_BRUSH);
SelectObject(hdc,hB1);
RoundRect(hdc,0,0,150,150,30,30);
SelectObject(hdc,hB2);
Ellipse(hdc,0,10,150,140);
EndPaint(hwnd,&ps);
DeleteObject(hB1);
DeleteObject(hB2);
break;
case WM_DESTROY:
PostQuitMessage(0);
break;
default:
return DefWindowProc(hwnd,message,wParam,lParam);
}
return 0;
}出现了连接错误，怎么解决？
error LNK2001: unresolved external symbol "long __stdcall WndProc(struct HWND__ *,unsigned int,unsigned int,long)" (?WndProc@@YGJPAUHWND__@@IIJ@Z)
Debug/映射模式.exe : fatal error LNK1120: 1 unresolved externals