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