The MessageBox function creates, displays, and operates a message box. The message box contains an application-defined message and title, plus any combination of predefined icons and push buttons.
int MessageBox(
|
HWND hWnd, |
// handle of owner window |
|
LPCTSTR lpText, |
// address of text in message box |
|
LPCTSTR lpCaption, |
// address of title of message box |
|
UINT uType |
// style of message box |
|
); |
Specify one of the following flags to indicate the buttons contained in the message box:
|
Flag |
Meaning |
|
MB_ABORTRETRYIGNORE |
The message box contains three push buttons: Abort, Retry, and Ignore. |
|
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. |
Specify one of the following flags to display an icon in the message box:
|
Flag |
Meaning |
|
MB_ICONEXCLAMATION, |
An exclamation-point icon appears in the message box. |
|
MB_ICONINFORMATION, 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. |
|
MB_ICONSTOP, |
A stop-sign icon appears in the message box. |
Specify one of the following flags to indicate the default button:
|
Flag |
Meaning |
|
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. |
Specify one of the following flags to indicate the modality of the dialog box:
|
Flag |
Meaning |
|
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 applications 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 application. 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 task 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 current application without suspending other applications. |
In addition, you can specify the following flags:
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 Windows NT version 4.0, the value of MB_SERVICE_NOTIFICATION has changed. See WINUSER.H for the old and new values. Windows NT 4.0 provides backward compatibility for pre-existing services by mapping the old value to the new value in the implementation of MessageBox and MessageBoxEx. This mapping is only done for executables that have a version number, as set by the linker, less than 4.0.
To build a service that uses MB_SERVICE_NOTIFICATION, and can run on both Windows NT 3.x and Windows NT 4.0, you have two choices.
|
|
The return value is zero if there is not enough memory to create the message box.
If the function succeeds, the return value is one of the following menu-item values returned by the dialog box:
|
Value |
Meaning |
|
IDABORT |
Abort button was selected. |
|
IDCANCEL |
Cancel button was selected. |
|
IDIGNORE |
Ignore button was selected. |
|
IDNO |
No button was selected. |
|
IDOK |
OK button was selected. |
|
IDRETRY |
Retry button was selected. |
|
IDYES |
Yes button was selected. |
If a message box has a Cancel button, the function returns the IDCANCEL value if either the ESC key is pressed or the Cancel button is selected. If the message box has no Cancel button, pressing ESC has no effect.
When you use a system-modal message box to indicate that the system is low on memory, the strings pointed to by the lpText and lpCaption parameters should not be taken from a resource file, because an attempt to load the resource may fail.
When an application calls MessageBox and specifies the MB_ICONHAND and MB_SYSTEMMODAL flags for the uType parameter, Windows displays the resulting message box regardless of available memory. When these flags are specified, Windows limits the length of the message box text to three lines. Windows does not automatically break the lines to fit in the message box, however, so the message string must contain carriage returns to break the lines at the appropriate places.
If you create a message box while a dialog box is present, use the handle of the dialog box as the hWnd parameter. The hWnd parameter should not identify a child window, such as a control in a dialog box.
Windows 95: The system can support a maximum of 16,364 window handles.
FlashWindow, MessageBeep, MessageBoxEx, MessageBoxIndirect, SetForegroundWindow