为窗体加上滚动条

为windows32窗体加入滚动条，代码如下：

#include<windows.h>
LRESULT CALLBACK WindowProc(
  HWND hwnd,      // handle to window
  UINT uMsg,      // message identifier
  WPARAM wParam,  // first message parameter
  LPARAM lParam   // second message parameter
);
int WINAPI WinMain(
  HINSTANCE hInstance,      // handle to current instance
  HINSTANCE hPrevInstance,  // handle to previous instance
  LPSTR lpCmdLine,          // command line
  int nCmdShow              // show state
  )
{
	static TCHAR szAppName[]=TEXT("AppName");
	HWND hwnd;
	MSG msg;
	WNDCLASS wndclass;
	wndclass.cbClsExtra=0;
	wndclass.cbWndExtra=0;
	wndclass.hbrBackground=(HBRUSH)GetStockObject(WHITE_BRUSH);
	wndclass.hCursor=LoadCursor(NULL,IDC_ARROW);
	wndclass.hIcon=LoadIcon(NULL,IDI_APPLICATION);
	wndclass.hInstance=hInstance;
	wndclass.lpfnWndProc=WindowProc;
	wndclass.lpszClassName=szAppName;
	wndclass.lpszMenuName=NULL;
	wndclass.style=CS_HREDRAW|CS_VREDRAW;

	if(!RegisterClass(&wndclass)){
		MessageBox(NULL,TEXT("This program requires Windows NT"),szAppName,MB_ICONERROR);
	}

	hwnd=CreateWindow(
  szAppName,  // registered class name
  TEXT("This is title"), // window name
  WS_OVERLAPPEDWINDOW|WS_VSCROLL,        // window style
  CW_USEDEFAULT,                // horizontal position of window
  CW_USEDEFAULT,                // vertical position of window
  CW_USEDEFAULT,           // window width
  CW_USEDEFAULT,          // window height
  NULL,      // handle to parent or owner window
  NULL,          // menu handle or child identifier
  hInstance,  // handle to application instance
  NULL        // window-creation data
);
	ShowWindow(hwnd,nCmdShow);
	UpdateWindow(hwnd);

	while(GetMessage(&msg,NULL,0,0)){
		TranslateMessage(&msg);
		DispatchMessage(&msg);
	}
	return msg.wParam;
}
LRESULT CALLBACK WindowProc(
  HWND hwnd,      // handle to window
  UINT uMsg,      // message identifier
  WPARAM wParam,  // first message parameter
  LPARAM lParam   // second message parameter
)
{
	static int cxClient,cyClient,cxChar,cyChar,iVscrollPos;
	HDC hdc;
	PAINTSTRUCT ps;
	int i=50,j=20;
	TCHAR szBuffer[20];
	TEXTMETRIC tm;
	int numberline=30;

	switch(uMsg){
		case WM_CREATE:
			//hdc=GetDC(hwnd);
			//TextOut(hdc,0,0,TEXT("hello,world"),strlen("hello,world"));
			//ReleaseDC(hwnd,hdc);
			hdc=BeginPaint(hwnd,&ps);
			GetTextMetrics(hdc,&tm);
			SetScrollRange(hwnd,SB_VERT,0,numberline-1,FALSE);
			SetScrollPos(hwnd,SB_VERT,iVscrollPos,TRUE);
			cyChar=(tm.tmHeight+tm.tmExternalLeading);
			EndPaint(hwnd,&ps);
			return 0;
		case WM_PAINT:
			hdc=BeginPaint(hwnd,&ps);
			GetTextMetrics(hdc,&tm);
			TextOut(hdc,iVscrollPos,iVscrollPos,szBuffer,wsprintf(szBuffer,TEXT("%d"),tm.tmAveCharWidth));//字符宽度
			TextOut(hdc,iVscrollPos+30,iVscrollPos+40,szBuffer,wsprintf(szBuffer,TEXT("%d"),tm.tmHeight+tm.tmExternalLeading));//字符长度
			EndPaint(hwnd,&ps);
			return 0;
		#include<windows.h>
L