This example begins window enumeration of all main windows (i.e. all immediate children of the Desktop), after which WinGetNextWindow is called in a loop to enumerate all the children, until all children are found and the enumeration ends.

#define INCL_WINWINDOWMGR       /* Window Manager Functions     */
#include <os2.h>

HWND  hwndParent;       /* Handle of the window whose child windows
                           are to be enumerated                 */
HWND  hwndNext;         /* current enumeration handle           */
HENUM  henum;           /* enumeration handle                   */
BOOL  fSuccess;         /* success indicator                    */
SHORT sRetLen;          /* returned string length               */
SHORT sLength = 10;     /* string buffer length                 */
char  pchBuffer[10];    /* string buffer                        */

hwndParent = HWND_DESKTOP;

henum = WinBeginEnumWindows(hwndParent);

while ((hwndNext = WinGetNextWindow(henum)) != NULLHANDLE) {
  .
  .
  .
}

fSuccess = WinEndEnumWindows (henum);