C# reference question
<p>Why does <strong>b.b</strong> would not change to "a2" as with f.f?</p>

<p>Thanks.</p>

<pre><code>public class Test
{
    public static void Main()
    {
        Foo f = new Foo
        {
            f = getStr()
        };

        Boo b = new Boo
        {
            b = f.f
        };


        f.f = "a2";

        Console.WriteLine(f.f);
        Console.WriteLine(b.b);
    }

    public static string getStr()
    {
        string a = "a1";
        return a;
    }
}

public class Foo
{
    public string f { get; set; }
}

public class Boo
{
    public string b { get; set; }
}
</code></pre>
