XtAppInitialize, XtVaAppInitialize - initialize, open, or close a display
#include <X11/Intrinsic.h>
Widget XtAppInitialize(XtAppContext* app_context_return,
    const char *application_class, XrmOptionDescRec* options,
    Cardinal num_options, int *argc_in_out, char
    **argv_in_out, String *fallback_resources, ArgList
    args, Cardinal num_args);
Widget XtVaAppInitialize(XtAppContext*
    app_context_return, const char *application_class,
    XrmOptionDescRec* options, Cardinal num_options, int
    *argc_in_out, char **argv_in_out, String
    *fallback_resources, ...);
  - app_context_return
- Specifies the application context.
- application_class
- Specifies the class name of this application, which usually is the generic
      name for all instances of this application.
- options
- Specifies how to parse the command line for any application-specific
      resources. The options argument is passed as a parameter to
      XrmParseCommand. For further information, see Xlib - C Language
      X Interface.
- num_options
- Specifies the number of entries in the options list.
- argc_in_out
- Specifies a pointer to the number of command line parameters.
- argv_in_out
- Specifies the command line parameters.
- fallback_resources
- Specifies resource values to be used if the application class resource
      file cannot be opened or read, or NULL.
- args
- Specifies the argument list to override any other resource specification
      for the created shell widget.
- num_args
- Specifies the number of entries in the argument list.
- ...
- Specifies the variable argument list to override any other resource
      specification for the created shell widget.
The XtAppInitialize function calls XtToolkitInitialize followed by
  XtCreateApplicationContext, then calls XtOpenDisplay with
  display_string NULL and application_name NULL, and finally calls
  XtAppCreateShell with application_name NULL, widget_class
  applicationShellWidgetClass, and the specified args and
  num_args and returns the created shell. The modified argc and
  argv returned by XtDisplayInitialize are returned in
  argc_in_out and argv_in_out. If app_context_return is not
  NULL, the created application context is also returned. If the display
  specified by the command line cannot be opened, an error message is issued and
  XtAppInitialize terminates the application. If
  fallback_resources is non-NULL, XtAppSetFallbackResources is
  called with the value prior to calling XtOpenDisplay.XtAppInitialize and XtVaAppInitialize have been superceded by
    XtOpenApplication and XtVaOpenApplication respectively.
XtOpenApplication(3), XtVaOpenApplication(3)
X Toolkit Intrinsics - C Language Interface
Xlib - C Language X Interface