Null – Conditional Operators in C# 6.0

Along with the nameof operator, C# 6.0 also introduced Null-Conditional operator that enable developers to check the null value with in an object reference chain. The null –  conditional operator ( ?.) , returns null if anything in the object reference chain in null. This avoid checking null for each and every nested objects if they are all in referenced and having null values.

Consider we have class called Student, and which having another property Address of type Address class. Now we can have the following code snippet to print the HomeAddress.

if (student != null && student.Address != null)
{
WriteLine(student.Address.HomeAddress);
}
else
{
WriteLine("No Home Address");
}

As we can see, to avoid  the null-reference exception, we have checked the null for student, and student.Address as they can have null reference as object.

Now, the above code block can be re-written using null – conditional ( ?.) operator as follows:

WriteLine(student?.Address?.HomeAddress ?? "No Home Address");

Isn’t it really nice. Instead of check each and individual objects, using ?. we can check entire chain of reference together and whenever there is a null values, it return null.  Following image illustrate how the ?. works.

Must Read : What’s new in C# 6.0

It also works nicely with methods, mainly when we triggers any events. Instead of writing

if (AddressChanged != null)
{
AddressChanged (this, EventArgs.Empty);
}

Using ?. we can rewrite,

AddressChanged ?.Invoke(this, EventArgs.Empty);