This example calls WinRegisterClass to register a class or returns FALSE if an error occurs.

#define INCL_WINWINDOWMGR
#include <OS2.H>
HAB hab;
CHAR szClassName[] = "Generic"; /* window class name      */
PFNWP pGenericWndProc;

 if (!WinRegisterClass(hab,   /* anchor-block handle       */
         szClassName,         /* class name                */
         pGenericWndProc,      /* window procedure          */
         0L,                  /* window style              */
         0))                  /* amount of reserved memory */
     return (FALSE);