The CREATESTRUCT structure 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 tagCREATESTRUCT { 
      LPVOID        lpCreateParams; 
      HINSTANCE     hInstance; 
      HMENU         hMenu; 
      HWND          hwndParent; 
      int           cy; 
      int           cx; 
      int           y; 
      int           x; 
      LONG          style; 
      LPCTSTR       lpszName; 
      LPCTSTR       lpszClass; 
      DWORD         dwExStyle; 
    } CREATESTRUCT; 

Memebers:

• lpCreateParams Long pointer to additional data that can be used to create the window. If the window is being created as a result of a call to the programming - windows - CreateWindowor CreateWindowEx function, this member contains the value of the lpParam parameter specified in the function call. If the window being created is an MDI window, this member contains a pointer to an MDICREATESTRUCT structure. Windows NT/2000 or later: 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 Handle to the module that owns the new window.
• hMenu Handle to the menu to be used by the new window.
• hwndParent 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 Specifies the height of the new window, in pixels.
• cx Specifies the width of the new window, in pixels.
• y Specifies 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 Specifies 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 Specifies the style for the new window.
• lpszName Long pointer to a null-terminated string that specifies the name of the new window.
• lpszClass Long pointer to a null-terminated string that specifies the class name of the new window.
• dwExStyle Specifies the extended style for the new window.

RemarksWindows NT/2000 or later: 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 code 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); 

Requirements

• Windows NT/2000 or later: Requires Windows NT 3.1 or later.
• Windows 95/98/Me: Requires Windows 95 or later.
• Header: Declared in Winuser.h; include Windows.h.
• Unicode: Declared as Unicode and ANSI structures.