Creates a new subwindow with numlines lines and numcols columns
    starting at the coordinates (begin_y,begin_x) on the terminal
    screen.

    Format

      #include  <curses.h>

      WINDOW *subwin  (WINDOW *win, int numlines, int numcols, int
                      begin_y, int begin_x);

1  –  Arguments

 win

    A pointer to the parent window.

 numlines

    The number of lines in the subwindow. If numlines is 0, then
    the function sets that dimension to LINES - begin_y. To get a
    subwindow of dimensions LINES by COLS, use the following format:

    subwin (win, 0, 0, 0, 0)

 numcols

    The number of columns in the subwindow. If numcols is 0, then
    the function sets that dimension to COLS - begin_x. To get a
    subwindow of dimensions LINES by COLS, use the following format:

    subwin (win, 0, 0, 0, 0)

 begin_y

    A window coordinate at which the subwindow is to be created.

 begin_x

    A window coordinate at which the subwindow is to be created.

2  –  Description

    When creating the subwindow, begin_y and begin_x are relative to
    the entire terminal screen. If either numlines or numcols is 0,
    then the subwin function sets that dimension to (LINES - begin_y)
    or (COLS - begin_x), respectively.

    The window pointed to by win must be large enough to contain the
    entire area of the subwindow. Any changes made to either window
    within the coordinates of the subwindow appear on both windows.

3  –  Return Values

    window pointer     A pointer to an instance of the structure
                       window corresponding to the newly created
                       subwindow.
    ERR                Indicates an error.