XOpenDisplay(3X11)  X Version 11 (Release 4)   XOpenDisplay(3X11)



  NAME
       XOpenDisplay, XCloseDisplay - connect or disconnect to X
       server

  SYNTAX
       Display *XOpenDisplay(display_name)
             char *display_name;

       XCloseDisplay(display)
             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 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.




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  XOpenDisplay(3X11)  X Version 11 (Release 4)   XOpenDisplay(3X11)



       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(3X11), XFlush(3X11), XSetCloseDownMode(3X11)
       Xlib - C Language X Interface













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