IsWindowhWnd

IsWindow(hWnd) is a Windows API function that checks whether a given window handle corresponds to a valid window or not. It is widely used in Windows programming and is a part of the User32 library. This function takes a pointer to a window handle as its sole argument.

The function returns a value that indicates whether the given window handle is valid or not. The return value is a non-zero integer when the handle is valid and zero otherwise. It is typically used in conjunction with other functions like IsWindowVisible and IsWindowEnabled to check the state of a window.

The process of checking whether a window handle is valid using IsWindow involves the following steps. The function searches for the window with the given handle starting from the window that has the focus (the active window). If the handle is found, the function returns a non-zero value; otherwise, it returns zero.

The typical function call for IsWindow(hWnd) is :

#define ISWINDOW(hWnd) IsWindow(hWnd)

In this case, hWnd is the window handle being checked. The function IsWindow checks whether hWnd corresponds to a valid window. If the window handle is valid, the function returns a non-zero value (typically 1); otherwise, it returns zero.

The function is very useful when working with windows in Windows programming and can help avoid certain types of errors. However, it should be used judiciously, as it can, in some cases, return a non-zero value even if the window appears to be invalid.