hpux man page for xdisplaywidth

XDisplayWidth*()														  XDisplayWidth*()

Name
  XDisplayWidth, XDisplayWidthMM, DisplayWidth, DisplayWidthMM - query width of screen in pixels or millimeters.

Synopsis
  int XDisplayWidthMM(display, screen_number)
	   Display *display;
	   int screen_number;

Arguments
  display   Specifies a connection to an X server; returned from XOpenDisplay().

  screen_number
	    Specifies the appropriate screen number on the server.

Returns
  The width in pixels or millimeters.

Description
  XDisplayWidth*() returns an integer that describes the width of the screen in pixels.  XDisplayWidthMM() returns the width of the specified
  screen in millimeters.

  The C language macros DisplayWidth() and DisplayWidthMM() are equivalent and slightly more efficient.

  These functions are misnamed; they should really be XScreenWidth() and XScreenWidthMM().

See Also
  XDisplayHeight*(), XDisplayHeightMM(), XGetWindowAttributes(), XGetGeometry().

Xlib - Macro Equivalents													  XDisplayWidth*()