This came up today in the office, so I thought i'd post a reminder of a useful operator in C# that first appeared in C# 2.0.

When Nullable Types were introduced, Microsoft also added an operator to make dealing with null values easier. This avoids a lot of if/else checking for null values.

The normal form is:  [variable] ?? [value if variable is null]

A simple example is when dealing with nullable types, like nullable int values -

int? i = null;
int? j = 42;

int result1 = i ?? 0; // result1 is 0
int result2 = j ?? 0; // result2 is 42

The results are: result1 = 0 (because i was null), and result2 = 42 (because j had a value).

The null coalescing operator removes a lot of the clutter of testing a variable for null and assigning a default value. This is often necessary when casting a nullable type back to its non-nullable counterpart.

To read more see lots of references on this Google  search.

Troy.