CreateDialogParamA function (winuser.h)

Article
02/09/2023

Creates a modeless dialog box from a dialog box template resource. Before displaying the dialog box, the function passes an application-defined value to the dialog box procedure as the lParam parameter of the WM_INITDIALOG message. An application can use this value to initialize dialog box controls.

Syntax

HWND CreateDialogParamA(
  [in, optional] HINSTANCE hInstance,
  [in]           LPCSTR    lpTemplateName,
  [in, optional] HWND      hWndParent,
  [in, optional] DLGPROC   lpDialogFunc,
  [in]           LPARAM    dwInitParam
);

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] lpTemplateName

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 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.

[in] dwInitParam

Type: LPARAM

The value to be passed to the dialog box procedure in the lParam parameter in the WM_INITDIALOG message.

Return value

Type: HWND

If the function succeeds, the return value is the window handle to the dialog box.

If the function fails, the return value is NULL. To get extended error information, call GetLastError.

Remarks

The CreateDialogParam function uses the CreateWindowEx function to create the dialog box. CreateDialogParam 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 if the template specifies the WS_VISIBLE style. Finally, CreateDialogParam returns the window handle of the dialog box.

After CreateDialogParam returns, the application displays the dialog box (if it is not already displayed) using the ShowWindow function. The application destroys the dialog box by using the DestroyWindow function. To support keyboard navigation and other dialog box functionality, the message loop for the dialog box must call the IsDialogMessage function.

Note

The winuser.h header defines CreateDialogParam as an alias which 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 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
API set	ext-ms-win-ntuser-dialogbox-l1-1-0 (introduced in Windows 8)