Represents a list of alternative items to make up an element in a grammar.

A Choices object represents a component of a phrase that can have one of several values. Use this class when creating a speech recognition grammar from a GrammarBuilder object.

For example, a Choices object could represent the component colorChoice in the phrase, "Change the color to colorChoice", where acceptable values for colorChoice are "red", or "green", or "blue".

Note
To use a Choices object as an optional component in a phrase, create the Choices object and add it to a GrammarBuilder..::..GrammarBuilder(GrammarBuilder, Int32, Int32) object with minRepeat and maxRepeat set to 0 and 1, respectively. Phrases containing optional components can be recognized whether or not the optional component is spoken.

The Choices class serves the same function as the one-of XML element defined by the Speech Recognition Grammar Specification (SRGS) Version 1.0, and is similar to the SrgsOneOf class in the Microsoft.Speech.Recognition.SrgsGrammar namespace.

The following example creates a speech recognition grammar for the phrase, "Set background to colorChoice", where colorChoice can be one of the defined colors. The GrammarBuilder is used to define the constraints for the grammar.

Copy Code

private Grammar CreateColorGrammar() { // Create a Choices object that contains a set of alternative colors. Choices colorChoice = new Choices(new string[] {"red", "green", "blue"}); colorChoice.Add(new string[] {"cyan", "yellow", "magenta"}); // Construct the phrase. GrammarBuilder builder = new GrammarBuilder("Set background to"); builder.Append(colorChoice); // Create a grammar for the phrase. Grammar colorGrammar = new Grammar(builder); colorGrammar.Name = "SetBackground"; return colorGrammar; }

Reference

Other Resources