C# CONCEPTS

Null-Coalescing assignment C# 8.0

C# 8.0 introduces the null-coalescing assignment operator ??=.

You can use the ??= operator to assign the value of its right-hand operand to its left-hand operand only if the left-hand operand is null.

Prerequisites

Let’s understand null coalescing ?? operator

The operator returns the value of left-hand operand if it’s “not null” otherwise the value of the right-hand operand is evaluated.

• The null coalescing operator was introduced in C# 7.0.
• This operator does not even evaluate the right-hand operand if the left-hand operator is not null.

Example

Let us consider an example of the following program, which covers both scenarios.

1. left-hand operand is null, so the value of 9.11 is evaluated and assigned to the output variable.

2. left-hand operand is not null, so the value of var2 is assessed and assigned to the output variable.

double? var1 = null;
double? var2 = 6.66;
double var3;