IsChild function (winuser.h)

Determines whether a window is a child window or descendant window of a specified parent window. A child window is the direct descendant of a specified parent window if that parent window is in the chain of parent windows; the chain of parent windows leads from the original overlapped or pop-up window to the child window.

BOOL IsChild(
  [in] HWND hWndParent,
  [in] HWND hWnd
);

[in] hWndParent

Type: HWND

A handle to the parent window.

[in] hWnd

Type: HWND

A handle to the window to be tested.

Type: BOOL

If the window is a child or descendant window of the specified parent window, the return value is nonzero.

If the window is not a child or descendant window of the specified parent window, the return value is zero.

Conceptual

IsWindow

Reference

SetParent

Windows