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Null-Conditional Operator New Feature in C# 6.0

One of the new features coming in C# 6.0 is the null-conditional operator.
If you have a reference-typed variable, it can have a null value or can refer to instance of the appropriate type.  You’ll often see the following pattern, checking for null before invoking a method on the object, to avoid a NullReferenceException.
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string sTest = DateTime.Now.Hour == 5 ? "Five" : null;
// OLD: Check for null to avoid NullReferenceException
string sLeft;
if (sTest != null)
    sLeft = sTest.Substring(0, 1);
The null-conditional operator allows us to do the same check for null, but in a more concise manner.
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// NEW: Null-Conditional operator
sLeft = sTest?.Substring(0, 1);
If sTest is non-null, the Substring method is called and the result is assigned to sLeft.  If sTest is null, the expression returns null, so a null value is assigned to sLeft.
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