| LONG GetWindowLong(hwnd, nIndex) | |||||
| HWND hwnd; | /* handle of window | */ | |||
| int nIndex; | /* offset of value to retrieve | */ | |||
This function retrieves information about the window identified by the hwnd parameter.
hwnd
Identifies the window.
nIndex
Specifies the byte offset of the value to be retrieved. It can also be one of the following values:
| Value | Meaning |
| GWL_EXSTYLE | ||
| Extended window style. | ||
| GWL_STYLE | ||
| Window style | ||
| GWL_WNDPROC | ||
| Long pointer to the window function | ||
| GWL_HINSTANCE | ||
| Handle of the instance. | ||
| GWL_HWNDPARENT | ||
| Handle of the parent window, if any. The SetParent function changes the parent window of a child window. An application should not call the SetWindowLong function to change the parent of a child window. | ||
| GWL_ID | ||
| Control ID of the child window. | ||
| GWL_USERDATA | ||
| This index can be used to access a LONG that is reserved in every window structure. This LONG is reserved specifically for applications. In general an application should not store values in this LONG if the associated window was created by some other application. | ||
The return value specifies information about the given window.
To access any extra four-byte values allocated when the window-class structure was created, use a positive byte offset as the index specified by the nIndex parameter, starting at zero for the first four-byte value in the extra space, 4 for the next four-byte value and so on.
SetParent, SetWindowLong, GetWindowWord, SetWindowWord