XOpenDisplay(3X11) X11R5 XOpenDisplay(3X11)Name
XOpenDisplay, XCloseDisplay - connect or disconnect to X server
display Specifies the connection to the X server.
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.
The function returns a structure that serves as the connection to the X
server and that contains all the information about that X server. con‐
nects your application to the X server through TCP or DECnet communica‐
tions protocols, if supported by your system, 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, attempts to connect 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, attempts to connect 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, returns a pointer to a structure, which is defined in If
does not succeed, it returns NULL. After a successful call to all of
the screens in the display can be used by the client. The screen num‐
ber specified in the display_name argument is returned by the macro (or
the function). You can access elements of the and structures only by
using the information macros or functions. For information about using
macros and functions to obtain information from the structure, see sec‐
tion 2.2.1 in X Window System: The Complete Reference, Second Edition,
Robert W. Scheifler and James Gettys.
The function closes the connection to the X server for the display
specified in the structure and destroys all windows, resource IDs and
or other resources that the client has created on this display, unless
the close-down mode of the resource has been changed (see Therefore,
these windows, resource IDs, and other resources should never be refer‐
enced again or an error will be generated. Before exiting, you should
call explicitly so that any pending errors are reported as performs a
can generate a error.
See AlsoAllPlanes(3X11), XFlush(3X11), XSetCloseDownMode(3X11)
X Window System: The Complete Reference, Second Edition, Robert W.
Scheifler and James Gettys