DialogBoxA macro (winuser.h)

Article
02/22/2024

Creates a modal dialog box from a dialog box template resource. DialogBox does not return control until the specified callback function terminates the modal dialog box by calling the EndDialog function.

DialogBox is implemented as a call to the DialogBoxParam function.

Syntax

void DialogBoxA(
  [in, optional]  hInstance,
  [in]            lpTemplate,
  [in, optional]  hWndParent,
  [in, optional]  lpDialogFunc
);

Parameters

[in, optional] hInstance

Type: HINSTANCE

A handle to the module which contains the dialog box template. If this parameter is NULL, then the current executable is used.

[in] lpTemplate

Type: LPCTSTR

The dialog box template. This parameter is either the pointer to a null-terminated character string that specifies the name of the dialog box template or an integer value that specifies the resource identifier of the dialog box template. If the parameter specifies a resource identifier, its high-order word must be zero and its low-order word must contain the identifier. You can use the MAKEINTRESOURCE macro to create this value.

[in, optional] hWndParent

Type: HWND

A handle to the window that owns the dialog box.

[in, optional] lpDialogFunc

Type: DLGPROC

A pointer to the dialog box procedure. For more information about the dialog box procedure, see DialogProc.

Return value

None

Remarks

The DialogBox macro uses the CreateWindowEx function to create the dialog box. DialogBox then sends a WM_INITDIALOG message (and a WM_SETFONT message if the template specifies the DS_SETFONT or DS_SHELLFONT style) to the dialog box procedure. The function displays the dialog box (regardless of whether the template specifies the WS_VISIBLE style), disables the owner window, and starts its own message loop to retrieve and dispatch messages for the dialog box.

When the dialog box procedure calls the EndDialog function, DialogBox destroys the dialog box, ends the message loop, enables the owner window (if previously enabled), and returns the nResult parameter specified by the dialog box procedure when it called EndDialog.

Examples

For an example, see Creating a Modal Dialog Box.

Note

The winuser.h header defines DialogBox as an alias that automatically selects the ANSI or Unicode version of this function based on the definition of the UNICODE preprocessor constant. Mixing usage of the encoding-neutral alias with code that is not encoding-neutral can lead to mismatches that result in compilation or runtime errors. For more information, see Conventions for Function Prototypes.

Requirements

Requirement	Value
Minimum supported client	Windows 2000 Professional [desktop apps only]
Minimum supported server	Windows 2000 Server [desktop apps only]
Target Platform	Windows
Header	winuser.h (include Windows.h)
Library	User32.lib
DLL	User32.dll

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