C# 5.0 Programmer's Reference

670 ❘ APPENDIX A Solutions to Exercises
}
authorListBox.DataSource = authors.ToArray();
This code uses LINQ to select the keys (author names). It converts the result into an array
and displays the names by setting the author ListBox’s DataSource property.
When the user clicks on an author, the following code displays that author’s book titles.
// Display the books by the selected author.
private void authorListBox_SelectedIndexChanged(object sender, EventArgs e)
{
string author = authorListBox.SelectedItem.ToString();
List books = Books[author];
booksListBox.DataSource = books;
}
This code gets the selected author’s name and then uses it to get the value for that author.
The value is a List containing the author’s book titles. The program converts that
into an array and displays the result in the book ListBox.
3. The BookNameValueCollection example program uses the following code to create and
initialize its NameValueCollection.
// The book data.
private NameValueCollection Books =
new NameValueCollection
{
{"Stephen King",
"Carrie,The Shining,The Stand"},
{"Tom Clancy",
"The Hunt for Red October,Red Storm Rising,Patriot Games"},
{"Agatha Christie",
"The Mysterious Affair at Styles,The Thirteen Problems"},
};
The collection’s initialization code contains three name/value pairs. The keys are author
names. Each of the values is a string holding an author’s book titles separated by commas.
When it loads, the program uses the following code to display the author names.
// Display the authors.
private void Form1_Load(object sender, EventArgs e)
{
var authors =
from name in Books.AllKeys
orderby name
select name;
authorListBox.DataSource = authors.ToArray();
}
This code uses LINQ to select the NameValueCollection’s keys (author names). It converts
the result into an array and displays the names by setting the author ListBox’s
DataSource property.
www.it-ebooks.info