NAME

       XOpenDisplay, XCloseDisplay - connect or disconnect to X server

SYNTAX

       Display *XOpenDisplay(_Xconst char *display_name);

       int XCloseDisplay(Display *display);

ARGUMENTS

       display   Specifies the connection to the X server.

       display_name
                 Specifies  the hardware display name, which determines the display and communications domain to
                 be used.  On a POSIX-conformant system, if the display_name is NULL, it defaults to  the  value
                 of the DISPLAY environment variable.

DESCRIPTION

       The  XOpenDisplay  function returns a Display structure that serves as the connection to the X server and
       that contains all the information about that X server.  XOpenDisplay connects your application to  the  X
       server  through TCP or DECnet communications protocols, or through some local inter-process communication
       protocol.  If the hostname is a host machine name and a single  colon  (:)  separates  the  hostname  and
       display  number,  XOpenDisplay  connects  using TCP streams.  If the hostname is not specified, Xlib uses
       whatever it believes is the fastest transport.  If the hostname is a host machine name and a double colon
       (::)  separates  the  hostname and display number, XOpenDisplay connects using DECnet.  A single X server
       can support any or all of these transport mechanisms simultaneously.  A  particular  Xlib  implementation
       can support many more of these transport mechanisms.

       If successful, XOpenDisplay returns a pointer to a Display structure, which is defined in X11/Xlib.h.  If
       XOpenDisplay does not succeed, it returns NULL.  After a successful call  to  XOpenDisplay,  all  of  the
       screens  in  the  display  can  be  used  by the client.  The screen number specified in the display_name
       argument is returned by the DefaultScreen  macro  (or  the  XDefaultScreen  function).   You  can  access
       elements  of  the  Display  and Screen structures only by using the information macros or functions.  For
       information about using macros and functions to  obtain  information  from  the  Display  structure,  see
       section 2.2.1.

       The XCloseDisplay function closes the connection to the X server for the display specified in the Display
       structure and destroys all windows, resource IDs (Window, Font, Pixmap, Colormap, Cursor, and  GContext),
       or  other  resources  that  the  client  has  created  on this display, unless the close-down mode of the
       resource has been changed (see XSetCloseDownMode).  Therefore, these windows,  resource  IDs,  and  other
       resources  should  never  be  referenced again or an error will be generated.  Before exiting, you should
       call XCloseDisplay explicitly so that any pending errors are reported as XCloseDisplay performs  a  final
       XSync operation.

       XCloseDisplay can generate a BadGC error.

SEE ALSO

       AllPlanes(3), XFlush(3), XSetCloseDownMode(3)
       Xlib - C Language X Interface