MessageBox function (winuser.h)
Displays a modal dialog box that contains a system icon, a set of buttons, and a brief application-specific message, such as status or error information. The message box returns an integer value that indicates which button the user clicked.
Syntax
Parameters
A handle to the owner window of the message box to be created. If this parameter is NULL, the message box has no owner window.
The message to be displayed. If the string consists of more than one line, you can separate the lines using a carriage return and/or linefeed character between each line.
The dialog box title. If this parameter is NULL, the default title is Error.
The contents and behavior of the dialog box. This parameter can be a combination of flags from the following groups of flags.
To indicate the buttons displayed in the message box, specify one of the following values.
| Value | Meaning |
|---|---|
| MB_ABORTRETRYIGNORE 0x00000002L | The message box contains three push buttons: Abort, Retry, and Ignore. |
| MB_CANCELTRYCONTINUE 0x00000006L | The message box contains three push buttons: Cancel, Try Again, Continue. Use this message box type instead of MB_ABORTRETRYIGNORE. |
| MB_HELP 0x00004000L | 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 0x00000000L | The message box contains one push button: OK. This is the default. |
| MB_OKCANCEL 0x00000001L | The message box contains two push buttons: OK and Cancel. |
| MB_RETRYCANCEL 0x00000005L | The message box contains two push buttons: Retry and Cancel. |
| MB_YESNO 0x00000004L | The message box contains two push buttons: Yes and No. |
| MB_YESNOCANCEL 0x00000003L | The message box contains three push buttons: Yes, No, and Cancel. |
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To display an icon in the message box, specify one of the following values.
| Value | Meaning |
|---|---|
| MB_ICONEXCLAMATION 0x00000030L | An exclamation-point icon appears in the message box. |
| MB_ICONWARNING 0x00000030L | An exclamation-point icon appears in the message box. |
| MB_ICONINFORMATION 0x00000040L | An icon consisting of a lowercase letter i in a circle appears in the message box. |
| MB_ICONASTERISK 0x00000040L | An icon consisting of a lowercase letter i in a circle appears in the message box. |
| MB_ICONQUESTION 0x00000020L | 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 0x00000010L | A stop-sign icon appears in the message box. |
| MB_ICONERROR 0x00000010L | A stop-sign icon appears in the message box. |
| MB_ICONHAND 0x00000010L | A stop-sign icon appears in the message box. |
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To indicate the default button, specify one of the following values.
| Value | Meaning |
|---|---|
| MB_DEFBUTTON1 0x00000000L | The first button is the default button. MB_DEFBUTTON1 is the default unless MB_DEFBUTTON2, MB_DEFBUTTON3, or MB_DEFBUTTON4 is specified. |
| MB_DEFBUTTON2 0x00000100L | The second button is the default button. |
| MB_DEFBUTTON3 0x00000200L | The third button is the default button. |
| MB_DEFBUTTON4 0x00000300L | The fourth button is the default button. |
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To indicate the modality of the dialog box, specify one of the following values.
| Value | Meaning |
|---|---|
| MB_APPLMODAL 0x00000000L | 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 pop-up windows are not. MB_APPLMODAL is the default if neither MB_SYSTEMMODAL nor MB_TASKMODAL is specified. |
| MB_SYSTEMMODAL 0x00001000L | 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 0x00002000L | 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. |
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To specify other options, use one or more of the following values.
| Value | Meaning | ||||||||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| MB_DEFAULT_DESKTOP_ONLY 0x00020000L | Same as desktop of the interactive window station. For more information, see Window Stations. If the current input desktop is not the default desktop, MessageBox does not return until the user switches to the default desktop. | ||||||||||||||||||||||||||||||
| MB_RIGHT 0x00080000L | The text is right-justified. | ||||||||||||||||||||||||||||||
| MB_RTLREADING 0x00100000L | Displays message and caption text using right-to-left reading order on Hebrew and Arabic systems. | ||||||||||||||||||||||||||||||
| MB_SETFOREGROUND 0x00010000L | The message box becomes the foreground window. Internally, the system calls the SetForegroundWindow function for the message box. | ||||||||||||||||||||||||||||||
| MB_TOPMOST 0x00040000L | The message box is created with the WS_EX_TOPMOST window style. | ||||||||||||||||||||||||||||||
| MB_SERVICE_NOTIFICATION 0x00200000L | 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 that the message box can appear on a desktop other than the desktop corresponding to the hWnd. For information on security considerations in regard to using this flag, see Interactive Services. In particular, be aware that this flag can produce interactive content on a locked desktop and should therefore be used for only a very limited set of scenarios, such as resource exhaustion. Return valueIf 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 will no effect — unless an MB_OK button is present. If an MB_OK button is displayed and the user presses ESC, the return value will be IDOK. If the function fails, the return value is zero. To get extended error information, call GetLastError. If the function succeeds, the return value is one of the following menu-item values.
RemarksThe following system icons can be used in a message box by setting the uType parameter to the corresponding flag value.
В Adding two right-to-left marks (RLMs), represented by Unicode formatting character U+200F, in the beginning of a MessageBox display string is interpreted by the MessageBox rendering engine so as to cause the reading order of the MessageBox to be rendered as right-to-left (RTL). 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. If you create a message box while a dialog box is present, use a handle to the dialog box as the hWnd parameter. The hWnd parameter should not identify a child window, such as a control in a dialog box. ExamplesIn the following example, the application displays a message box that prompts the user for an action after an error condition has occurred. The message box displays the message that describes the error condition and how to resolve it. The MB_CANCELTRYCONTINUE style directs MessageBox to provide three buttons with which the user can choose how to proceed. The MB_DEFBUTTON2 style sets the default focus on the second button of the message box, in this case, the Try Again button. The following image shows the output from the preceding code example: For another message box example, see Displaying a Message Box. Message Box Options ПеречислениеОпределениеЗадает параметры в MessageBox. Specifies options on a MessageBox. Это перечисление имеет атрибут FlagsAttribute, который разрешает побитовое сочетание значений его элементов. Данное окно сообщения отображается на активном рабочем столе. The message box is displayed on the active desktop. Эта константа аналогична ServiceNotification , за исключением того, что в системе окно сообщения отображается только на стандартном рабочем столе интерактивного оконного терминала. This constant is similar to ServiceNotification , except that the system displays the message box only on the default desktop of the interactive window station. Приложение, отображающее окно сообщения, теряет фокус, и окно сообщения отображается без стилей оформления. The application that displayed the message box loses focus, and the message box is displayed without using visual styles. Дополнительные сведения см. в разделе Отрисовка элементов управления с помощью визуальных стилей. For more information, see Rendering Controls with Visual Styles. Текст в окне сообщения выравнивается по правому краю. The message box text is right-aligned. Указывает, что текст в данном окне сообщения отображается с порядком чтения справа налево. Specifies that the message box text is displayed with right to left reading order. Данное окно сообщения отображается на активном рабочем столе. The message box is displayed on the active desktop. Вызывающий объект — это служба, которая уведомляет пользователя о событии. The caller is a service notifying the user of an event. Show отображает окно сообщения на активном в настоящий момент рабочем столе, даже если пользователь не вошел в систему. Show displays a message box on the current active desktop, even if there is no user logged on to the computer. ПримерыВ следующем примере показано, как отобразить MessageBox с параметрами, поддерживаемыми перегрузками MessageBox.Show , включающими options параметр. The following example demonstrates how to display a MessageBox with the options supported by the overloads of MessageBox.Show that include an options parameter. После проверки того, что строковая переменная ServerName пуста, в примере отображается MessageBox значок с полем вопроса, предлагающий пользователю отменить операцию. After verifying that a string variable, ServerName , is empty, the example displays a MessageBox with a question box icon, offering the user the option to cancel the operation. В примере MessageBoxOptions.RightAlign элемент перечисления используется для выровняйте текст по правому краю диалогового окна. The example uses the MessageBoxOptions.RightAlign enumeration member to align the text to the right edge of the dialog box. Если Show возвращаемое значение метода равно DialogResult.Yes , то форма, на которой отображается, MessageBox закрывается. If the Show method’s return value evaluates to DialogResult.Yes, the form that displayed the MessageBox is closed. КомментарииЭто перечисление используется классом MessageBox. This enumeration is used by the MessageBox class. Если не нужно указывать аргумент при вызове методов в MessageBox , вместо этого можно передать значение 0. If you do not want to specify an argument when calling methods on MessageBox, you can pass in 0 instead. |
