滚动条例题

#include <windows.h>
#include <stdio.h>
#include <string.h>
LRESULT CALLBACK WndProc(HWND, UINT, WPARAM, LPARAM);

int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance,
LPSTR lpCmdLine, int nCmdShow){
static TCHAR szAppName[] = TEXT("SimpleDisplay");
static TCHAR szClassName[] = TEXT("SimpleDisplayClass");
static TCHAR szWinName[] = TEXT("Source Text Simple Display Program");
HWND hwnd;
MSG msg;
WNDCLASS wndclass;

//typedef the class of the window
wndclass.style = CS_HREDRAW | CS_VREDRAW;
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 = szClassName;

//regist window
if(!RegisterClass(&wndclass)){
MessageBox(NULL,TEXT("This program requires Windows NT!"),
szAppName,MB_ICONERROR);
return 0;
}
//RegisterClass(&wndclass);
//create window
hwnd = CreateWindow(
szClassName,
szWinName,
WS_OVERLAPPEDWINDOW | WS_HSCROLL |WS_VSCROLL,
CW_USEDEFAULT,
CW_USEDEFAULT,
CW_USEDEFAULT,
CW_USEDEFAULT,
NULL,
NULL,
hInstance,
NULL );

//show window
ShowWindow(hwnd, nCmdShow);

//update window
UpdateWindow(hwnd);

//message circle
while(GetMessage(&msg, NULL, 0, 0)){
TranslateMessage(&msg);
DispatchMessage(&msg);
}

return msg.wParam;
}