XQueryExtension(3X11) manual page

Table of Contents

## Name

XQueryExtension, XListExtensions, XFreeExtensionList - list available extensions

## Syntax

Bool XQueryExtension(display, name, major_opcode_return, first_event_return, first_error_return)
char **XListExtensions(display, nextensions_return)
XFreeExtensionList(list)

## Arguments

display
  Specifies the connection to the X server.
name
  Specifies the extension name.
major_opcode_return
  Returns the major opcode.
first_event_return
  Returns the first event code, if any.
first_error_return
  Returns the first error code, if any.
nextensions_return
  Returns the number of extensions listed.
list
  Specifies the list of extension names.

## Description

The XQueryExtension function determines if the named extension is present. If the extension is not present, XQueryExtension returns False; otherwise, it returns True. If the extension is present, XQueryExtension returns the major opcode for the extension to major_opcode_return; otherwise, it returns zero. Any minor opcode and the request formats are specific to the extension. If the extension involves additional event types, XQueryExtension returns the base event type code to first_event_return; otherwise, it returns zero. The format of the events is specific to the extension. If the extension involves additional error codes, XQueryExtension returns the base error code to first_error_return; otherwise, it returns zero. The format of additional data in the errors is specific to the extension. If the extension name is not in the Host Portable Character Encoding the result is implementation-dependent. Uppercase and lowercase matter; the strings ``thing'', ``Thing'', and ``thinG'' are all considered different names.

The XListExtensions function returns a list of all extensions supported by the server. If the data returned by the server is in the Latin Portable Character Encoding, then the returned strings are in the Host Portable Character Encoding. Otherwise, the result is implementation-dependent.

The XFreeExtensionList function frees the memory allocated by XListExtensions.

Table of Contents

- Name
- Syntax
- Arguments
- Description