This example checks if a rectangle is empty (i.e. it has no area).

#define INCL_WINRECTANGLES      /* Window Rectangle Functions   */
#include <os2.h>

BOOL  fEmpty;           /* empty indicator                      */
HAB     hab;            /* anchor-block handle                  */
RECTL prclRect1 = {0,0,100,100}; /* rectangle                   */

fEmpty = WinIsRectEmpty(hab, &prclRect1);