C#

Regex r = new Regex("^a");<br />
will only match "a" if it occurs at the begining of the string, and:<br />
<code>Regex r = new Regex("a$");<br />
will match it at the end. The trouble is I want to match "a" when it doesn't appear at the begining or the end of a string. There doesn't seem to be a way to say not begining and not end though? Does anybody know if such a thing is possible? I could use:<br />
<code>Regex r = new Regex(".a.");

<br />
    private void myApp_KeyDown(object sender, System.Windows.Forms.KeyEventArgs e)<br />
	{<br />
	  MessageBox.Show("KeyDown");<br />
	  e.Handled=false;<br />
	}<br />
	<br />
<br />
    private void myApp_KeyUp(object sender, System.Windows.Forms.KeyEventArgs e)<br />
	{<br />
	  MessageBox.Show("KeyUp");<br />
	}<br />

<br />
public class TestMessageFilter: IMessageFilter<br />
{...}<br />

<br />
public bool HandleKeys(Keys keyCode)<br />
        {<br />
          bool ret = true;<br />
<br />
          switch(keyCode) {<br />
            case Keys.Shift: ...do stuff...<br />
            default:          ret         = false;          break;<br />
          }<br />
          return ret;<br />
        }<br />