NullCheck with C# 6.0

C# 6.0 provides a new way of checking null values compared to its traditional ways.

In earlier versions, to avoid a nullpointerexception, we need to do null checking before invocation of a function.

C# 6.0 provides a null-conditional operator (?) that can be used to avoid writing redundant code every time a null check must be done.

However, developers need to be cautious about its usage and return a value assigned to variables. The null-conditional operator short-circuits the actual operation and performs a null check. The result of the short circuiting is NULL if the operand itself is null. Siince null values cannot be assigned to value types, using a null-conditional operator as shown below would throw a compile time error:

In the list of advancements of the null checking, the Null-conditional operator can also be used to check on indexers, in other words check a collection to determine if it is null before retrieving an item from a collection.
The null-conditional index form of the operator ? causes indexing into a collection to occur only if the collection isn't null. That is programmatically equivalent to:
Note that the null-conditional operator can only retrieve items. It won’t work to assign an item. Also pay attention to the implicit ambiguity when using the ? […] operator on a reference type. Because reference types can be null, a null result from the ? […] operator should not be mistaken with whether the collection was null or the element itself was, in fact, null.

Another common pattern where the null-conditional operator could be used is in combination with the coalesce operator. Instead of checking for null on docList before invoking Length, you can retrieve an item count as follows: