CREATESTRUCTA structure (winuser.h)
Defines the initialization parameters passed to the window procedure of an application. These members are identical to the parameters of the CreateWindowEx function.
Syntax
typedef struct tagCREATESTRUCTA {
LPVOID lpCreateParams;
HINSTANCE hInstance;
HMENU hMenu;
HWND hwndParent;
int cy;
int cx;
int y;
int x;
LONG style;
LPCSTR lpszName;
LPCSTR lpszClass;
DWORD dwExStyle;
} CREATESTRUCTA, *LPCREATESTRUCTA;
Members
lpCreateParams
Type: LPVOID
Contains additional data which may be used to create the window. If the window is being created as a result of a call to the CreateWindow or CreateWindowEx function, this member contains the value of the lpParam parameter specified in the function call.
If the window being created is a MDI client window, this member contains a pointer to a CLIENTCREATESTRUCT structure. If the window being created is a MDI child window, this member contains a pointer to an MDICREATESTRUCT structure.
If the window is being created from a dialog template, this member is the address of a SHORT value that specifies the size, in bytes, of the window creation data. The value is immediately followed by the creation data. For more information, see the following Remarks section.
hInstance
Type: HINSTANCE
A handle to the module that owns the new window.
hMenu
Type: HMENU
A handle to the menu to be used by the new window.
hwndParent
Type: HWND
A handle to the parent window, if the window is a child window. If the window is owned, this member identifies the owner window. If the window is not a child or owned window, this member is NULL.
cy
Type: int
The height of the new window, in pixels.
cx
Type: int
The width of the new window, in pixels.
y
Type: int
The y-coordinate of the upper left corner of the new window. If the new window is a child window, coordinates are relative to the parent window. Otherwise, the coordinates are relative to the screen origin.
x
Type: int
The x-coordinate of the upper left corner of the new window. If the new window is a child window, coordinates are relative to the parent window. Otherwise, the coordinates are relative to the screen origin.
style
Type: LONG
The style for the new window. For a list of possible values, see Window Styles.
lpszName
Type: LPCTSTR
The name of the new window.
lpszClass
Type: LPCTSTR
A pointer to a null-terminated string or an atom that specifies the class name of the new window.
dwExStyle
Type: DWORD
The extended window style for the new window. For a list of possible values, see Extended Window Styles.
Remarks
Because the lpszClass member can contain a pointer to a local (and thus inaccessible) atom, do not obtain the class name by using this member. Use the GetClassName function instead.
You should access the data represented by the lpCreateParams member using a pointer that has been declared using the UNALIGNED type, because the pointer may not be DWORD aligned. This is demonstrated in the following example:
typedef struct tagMyData
{
// Define creation data here.
} MYDATA;
typedef struct tagMyDlgData
{
SHORT cbExtra;
MYDATA myData;
} MYDLGDATA, UNALIGNED *PMYDLGDATA;
PMYDLGDATA pMyDlgdata = (PMYDLGDATA) (((LPCREATESTRUCT) lParam)->lpCreateParams);
Note
The winuser.h header defines CREATESTRUCT 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] |
| Header | winuser.h (include Windows.h) |
See also
About the Multiple Document Interface
Conceptual
Reference