NCURSES_EXPORT(int)
wrefresh(WINDOW *win)
{
    int code;

    T((T_CALLED("wrefresh(%p)"), win));

    if (win == 0) {
        code = ERR;
    } else if (win == curscr) {


from http://en.wikipedia.org/wiki/Boolean_datatype:

However, any non-zero value represents true in C. So while in other languages, if (foo == TRUE) ... is merely redundant, in C, it is actually incorrect code.