null-coalescing operator or conditional operator
<p>Which coding style do you prefer:</p>

<pre><code>object o = new object();
//string s1 =  o ?? "Tom"; // Cannot implicitly convert type 'object' to 'string' CS0266
string s3 = Convert.ToString(o ?? "Tom");
string s2 = (o != null) ? o.ToString() : "Tom";
</code></pre>

<p>s2 or s3?</p>

<p>Is it possible to make it shorter? s1 does not obviously work.</p>
