GrammarBuilder.AppendWildcard Method

Appends a recognition grammar element that matches any input.

Namespace: Microsoft.Speech.Recognition
Assembly: Microsoft.Speech (in microsoft.speech.dll)

Syntax

'Declaration
Public Sub AppendWildcard

public void AppendWildcard ()

public:
void AppendWildcard ()

public void AppendWildcard ()

public function AppendWildcard ()

Remarks

The grammar element appended to a GrammarBuilder by calling AppendWildcard will match any spoken word. It will not match background noise or silence.

Example

The example below defines a Grammar and an Grammar.SpeechRecognized event handler designed to process password input of the form "My password is [wildcard]".

The example is implemented by creating two GrammarBuilder instances: one (pwdBuilder) constructed with the "My password"; the other (wildcardBuilder) uses the default GrammarBuilder constructor, has a wild card appended to it, and has a semantic key applied to it. The two GrammarBuilder instances are then added together.

private void pwdGrammar() {
    GrammarBuilder pwdBuilder = new GrammarBuilder("My Password is");
    GrammarBuilder wildcardBuilder = new GrammarBuilder();
    wildcardBuilder.AppendWildcard();
    SemanticResultKey pwd = new SemanticResultKey("Password", wildcardBuilder);
    pwdBuilder += pwd;
    Grammar grammar = new Grammar(pwdBuilder);
    grammar.Name = "Password input";
    grammar.SpeechRecognized +=
            delegate(object sender, SpeechRecognizedEventArgs eventArgs) {
                SemanticValue semantics = eventArgs.Result.Semantics;
                RecognitionResult result = eventArgs.Result;

                if (!semantics.ContainsKey("Password")) {

                    SpeechUI.SendTextFeedback(eventArgs.Result,
                                              "No Password Provided", false);
                } else {

                    RecognizedAudio pwdAudio = result.GetAudioForWordRange(result.Words[3],
                                                                result.Words[result.Words.Count - 1]);
                    MemoryStream pwdMemoryStream = new MemoryStream();
                    pwdAudio.WriteToAudioStream(pwdMemoryStream);
                    if (!IsValidPwd(pwdMemoryStream)) {
                        string badPwd = System.IO.Path.GetTempPath() + "BadPwd" + (new Random()).Next().ToString() + ".wav";
                        FileStream waveStream = new FileStream(badPwd, FileMode.Create);
                        pwdAudio.WriteToWaveStream(waveStream);
                        waveStream.Flush();
                        waveStream.Close();
                        SpeechUI.SendTextFeedback(eventArgs.Result,
                                                  "Invalid Password", false);

                    }
                }
            };
    grammar.Enabled = true;
    _recognizer.LoadGrammar(grammar);
    UpdateGrammarTree(_grammarTreeView, _recognizer);

}

Thread Safety

All public static (Shared in Visual Basic) members of this type are thread-safe. Instance members are not guaranteed to be thread-safe.

Platforms

Development Platforms

Windows XP Professional with Service Pack 2 (SP2), Windows Server 2003, Windows Vista Ultimate Edition, Windows Vista Business Edition, Windows Vista Enterprise Edition

Target Platforms

See Also

Reference

GrammarBuilder Class
GrammarBuilder Members
Microsoft.Speech.Recognition Namespace