Different Ways of using the C# Null Coalescing Operator

Hi frienz,

The C# Null-Coalescing operator or the ?? operator is a binary operator that returns the left-hand operand if it is not null; otherwise it returns the right operand. It can be used with both nullable and reference types.

Here’s a simple example of using the Null-Coalescing operator

int? i = null;
int j = i ?? 2;
// here the resultant value of j is 2

Here are some additional ways of using the Null-Coalescing operator in your code.

Method 1

string address = homeAddress1 ?? homeAddress2 ?? officeAddress
                 ??  "No Address";

returns the first non-null value in this long expression. This expression returns “No Address” if homeAddress1, homeAddress2 and officeAddress are Null.


Method 2

While converting a Nullable Type to Non-Nullable type, we do an explicit cast to avoid assigning null values to a non-nullable type, as shown below:

int? a = NullType(); // returns nullable int
int b = (int)a;

instead you can avoid the explicit cast using a null-coalescing operator and write:

int? a = NullType();
int b = a ?? 0;

Method 3

private IList<Person> person;
public IList<Person> PersonList
{
    get
    {
        return person ?? (person = new List<Person>());
    }
}

Typical usage of the null-coalescing operator in a lazy instantiated private variable.

Method 4

string conn = Connection["TestMachineStr1"]
            ?? AppConnection["ProdMachineStr2"]
            ?? DefaultConnection["DefaultConn"];

Accessing NameValueCollections and choosing the first non-null value.

Note: The Null-Coalescing operator is useful but may sometimes be an overkill, especially when developers use it to flaunt their coding skills. I sometimes choose ‘understandable code’ over ‘terse code’, focusing on the intent.

Feel free to use the comments section to demonstrate how you have used the null-coalescing operator in your projects.

 

 

Have a nice day... 'N happy Coding :)