麻烦各位了，提示找不到我定义的文件

源代码为# include<windows.h>
# include" 7_1.h"
# include <stdio.h>HMENU hmenu,haddmenu;
HACCEL hAccel;
LRESULT CALLBACK WinSunProc(
  HWND hwnd,      
  UINT uMsg,      
  WPARAM wParam,  
  LPARAM lParam   
);
WINAPI WinMain(
  HINSTANCE hInstance,      
  HINSTANCE hPrevInstance,  
  LPSTR lpCmdLine,          
  int nCmdShow              
){
WNDCLASS wndclass1;
wndclass1.style=CS_HREDRAW | CS_VREDRAW;
wndclass1.lpfnWndProc=WinSunProc;
wndclass1.cbClsExtra=0;
wndclass1.cbWndExtra=0;
wndclass1.hInstance=hInstance;
wndclass1.hIcon=LoadIcon(NULL,IDI_ERROR);
wndclass1.hCursor=LoadCursor(NULL,IDC_CROSS);
wndclass1.lpszClassName="Winged Monkey";
wndclass1.lpszMenuName="I will";
wndclass1.hbrBackground=(HBRUSH)GetStockObject(WHITE_BRUSH);
RegisterClass(&wndclass1);
HWND hwnd;
hwnd=CreateWindow("Winged Monkey","I will",WS_OVERLAPPEDWINDOW,0,0,400,300,NULL,hmenu,hInstance,NULL);
ShowWindow(hwnd,SW_SHOWNORMAL);
UpdateWindow(hwnd);
hAccel=LoadAccelerators(hInstance,"I will");
MSG msg;
while(GetMessage(&msg,NULL,0,0))
{
if(!TranslateAccelerator(hwnd,hAccel,&msg))
{
TranslateMessage(&msg);
DispatchMessage(&msg);
}
}
}LRESULT CALLBACK WinSunProc(
  HWND hwnd,      
  UINT uMsg,      
  WPARAM wParam,  
  LPARAM lParam   
)
{
   switch(uMsg)
   {  
      case WM_COMMAND:
      switch(wParam)
  {
   case IDM_ADDMENU://在主菜单中添加弹出式菜单
   hmenu=GetMenu(hwnd);  
   haddmenu=CreateMenu();
   AppendMenu(haddmenu,MF_ENABLED,IDM_fangcha,"方差");
   AppendMenu(haddmenu,MF_ENABLED,IDM_junfanggen,"均方根");
   AppendMenu(haddmenu,MF_ENABLED,IDM_pingjunzhi,"平均值");
   AppendMenu(haddmenu,MF_ENABLED,IDM_quihe,"求和");
   InsertMenu(hmenu,2,MF_POPUP|MF_BYPOSITION,(UINT)haddmenu,"统计计算");
       EnableMenu(hmenu,IDM_ADDMENU,MF_GRAYED);
   EnableMenu(hmenu,IDM_DELMENU,MF_ENABLED);
   DrawMenuBar(hwnd); //重新显示窗口
   break;
  }
      case IDM_DELEMENU:
      DeleteMenu(hmenu,2,BYPOSITION);
      EnableMenu(hmenu,IDM_ADDMENU,MF_ENABLED);
  EnableMenu(hmenu,IDM_DELMENU,MF_GRAYED);
   DrawMenuBar(hwnd);
      break;
 case WM_CLOSE:
      if(IDYES==MessageBox(hwnd,"是否真的要结束","Winged Monkey",MB_YESNO))
  {
      DestroyWindow(hwnd);
  }
      case WM_DESTROY:
      PostQuitMessage(0);
      default:
      return DefWindowProc(hwnd,uMsg,wParam,lParam);
   }
}
提示错误为Cannot open include file: ' 7_1.h': No such file or directory
执行 cl.exe 时出错.但是我定义了7_1.h到Header Files中啊