#include <windows.h>
//
// Windows CE 开发环境使用标准的Windows入口点，形式如下
//
int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance,
LPWSTR lpCmdLine, int nCmdShow) {
printf ("Hello World\n"); //Windows CE支持大多数标准C库函数
return 0; //传递到return函数的值，可以被其他进程使用，使用Win32 API GetExitCodeProcess函数就可以得到这个值
}
//hInstance :用来确定一个程序的实例，供其他应用程序和需要找到EXE程序实例的Windows API函数使用。
//hPreInstance:这是从旧的Win16 API遗留下来的，为0并且可以忽略
//lpCmdLine:指向一个包含命令行参数文本的Unicode字符串
//nCmdShow:指定了程序主窗口的初始化状态：只有三种：SW_SHOW SW_HIDDEN SW_SHOWNOACTIVATE
在运行此程序时，模拟器屏幕看起来只是闪了一下，是因为在这个程序运行时，只进行了控制台输出文本动作，然后就终止了。除非你从一个已经创建的控制台来运行这个程序，否则Windows CE只在此程序执行到printf语句时，才创建控制台窗口，然后在此程序终止后，自动关闭控制台。
于是我们现在要用到一个最常用的API：MessageBox
int MessageBox(
HWND hWnd, //顶级窗口的句柄
LPCTSTR lpText, //显示在窗口中的文本
LPCTSTR lpCaption, //显示在窗口的标题栏中的文本
UINT uType //指定这个消息框以何种方式出现
);
MB_ABORTRETRYIGNORE The message box contains three push buttons: Abort, Retry, and Ignore. MB_CANCELTRYCONTINUE Microsoft Windows 2000/XP: The message box contains three push buttons: Cancel, Try Again, Continue. Use this message box type instead of MB_ABORTRETRYIGNORE. MB_HELP Windows 95/98/Me, Windows NT 4.0 and later: Adds a Help button to the message box. When the user clicks the Help button or presses F1, the system sends a WM_HELP message to the owner. MB_OK The message box contains one push button: OK. This is the default. MB_OKCANCEL The message box contains two push buttons: OK and Cancel. MB_RETRYCANCEL The message box contains two push buttons: Retry and Cancel. MB_YESNO The message box contains two push buttons: Yes and No. MB_YESNOCANCEL The message box contains three push buttons: Yes, No, and Cancel. To display an icon in the message box, specify one of the following values. MB_ICONEXCLAMATION An exclamation-point icon appears in the message box. MB_ICONWARNING An exclamation-point icon appears in the message box. MB_ICONINFORMATION An icon consisting of a lowercase letter i in a circle appears in the message box. MB_ICONASTERISK An icon consisting of a lowercase letter i in a circle appears in the message box. MB_ICONQUESTION A question-mark icon appears in the message box. The question mark message icon is no longer recommended because it does not clearly represent a specific type of message and because the phrasing of a message as a question could apply to any message type. In addition, users can confuse the message symbol question mark with Help information. Therefore, do not use this question mark message symbol in your message boxes. The system continues to support its inclusion only for backward compatibility. MB_ICONSTOP A stop-sign icon appears in the message box. MB_ICONERROR A stop-sign icon appears in the message box. MB_ICONHAND A stop-sign icon appears in the message box. To indicate the default button, specify one of the following values. MB_DEFBUTTON1 The first button is the default button. MB_DEFBUTTON1 is the default unless MB_DEFBUTTON2, MB_DEFBUTTON3, or MB_DEFBUTTON4 is specified. MB_DEFBUTTON2 The second button is the default button. MB_DEFBUTTON3 The third button is the default button. MB_DEFBUTTON4 The fourth button is the default button. To indicate the modality of the dialog box, specify one of the following values. MB_APPLMODAL The user must respond to the message box before continuing work in the window identified by the hWnd parameter. However, the user can move to the windows of other threads and work in those windows. Depending on the hierarchy of windows in the application, the user may be able to move to other windows within the thread. All child windows of the parent of the message box are automatically disabled, but popup windows are not. MB_APPLMODAL is the default if neither MB_SYSTEMMODAL nor MB_TASKMODAL is specified. MB_SYSTEMMODAL Same as MB_APPLMODAL except that the message box has the WS_EX_TOPMOST style. Use system-modal message boxes to notify the user of serious, potentially damaging errors that require immediate attention (for example, running out of memory). This flag has no effect on the user's ability to interact with windows other than those associated with hWnd. MB_TASKMODAL Same as MB_APPLMODAL except that all the top-level windows belonging to the current thread are disabled if the hWnd parameter is NULL. Use this flag when the calling application or library does not have a window handle available but still needs to prevent input to other windows in the calling thread without suspending other threads. To specify other options, use one or more of the following values. MB_DEFAULT_DESKTOP_ONLY Windows NT/2000/XP: Same as MB_SERVICE_NOTIFICATION except that the system will display the message box only on the default desktop of the interactive window station. For more information, see Window Stations. Windows NT 4.0 and earlier: If the current input desktop is not the default desktop, MessageBox fails. Windows 2000/XP: If the current input desktop is not the default desktop, MessageBox does not return until the user switches to the default desktop. Windows 95/98/Me: This flag has no effect. MB_RIGHT The text is right-justified. MB_RTLREADING Displays message and caption text using right-to-left reading order on Hebrew and Arabic systems. MB_SETFOREGROUND The message box becomes the foreground window. Internally, the system calls the SetForegroundWindow function for the message box. MB_TOPMOST The message box is created with the WS_EX_TOPMOST window style. MB_SERVICE_NOTIFICATION Windows NT/2000/XP: The caller is a service notifying the user of an event. The function displays a message box on the current active desktop, even if there is no user logged on to the computer. Terminal Services: If the calling thread has an impersonation token, the function directs the message box to the session specified in the impersonation token. If this flag is set, the hWnd parameter must be NULL. This is so the message box can appear on a desktop other than the desktop corresponding to the hWnd. For more information on the changes between Microsoft Windows NT 3.51 and Windows NT 4.0, see Remarks. MB_SERVICE_NOTIFICATION_NT3X Windows NT/2000/XP: This value corresponds to the value defined for MB_SERVICE_NOTIFICATION for Windows NT version 3.51.
MessageBox函数的返回值记录了用户按下的按钮。可能的返回值如下：
| IDABORT | Abort 按钮按下 |
| IDCANCEL | Cancel 按钮按下 |
| IDCONTINUE | Continue 按钮按下 |
| IDIGNORE | Ignore 按钮按下 |
| IDNO | 没有按钮按下 |
| IDOK | OK 按钮按下 |
| IDRETRY | Retry 按钮按下 |
| IDTRYAGAIN | Try Again 按钮按下 |
| IDYES | Yes 按钮按下 |
改成：
#include <windows.h>
int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance,
LPWSTR lpCmdLine, int nCmdShow) {
MessageBox (NULL, TEXT ("Hello World"), TEXT ("Hello2"), MB_OK);
return 0;
}
运行：
