c# Windows form application error on comboBox
<p>I am new to c# windows form app. Here is my question:
I created a comboBox in a form, and add items to this comboBox as below:</p>

<pre><code>foreach (string name in seqNames)
{

    comboBox.items.add(name);
}
</code></pre>

<p>and later check if any comboBox item is selected by</p>

<pre><code>if (comboBox.selectedItem.toString().length &gt; 0)
{
      blabla;
}
</code></pre>

<p>but when I run it, without select any item in this combo box, I got an error : 
"Object reference not set to an instance of an object". </p>

<p>Anyone help me out? Please.....
Thanks in advance.</p>
