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XOpenDisplay(3)


NAME

   XOpenDisplay, XCloseDisplay - connect or disconnect to X server

SYNTAX

   Display *XOpenDisplay(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



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