Microsoft Certified Solutions Developer (MCSD) Certification Practice Test

What is the function of the Null-Coalescing operator (??)?

1. To combine delegates into a single one

2. To provide a default value when a nullable type is null

3. To create an event handler

4. To handle exceptions

The correct answer is: To provide a default value when a nullable type is null

The Null-Coalescing operator (??) is specifically designed to handle situations where a nullable type might not have a value, providing a default value when such a scenario arises. This operator checks the operand on its left side, and if that operand is null, it returns the value of the right operand instead. This is particularly useful in scenarios where you want to assign a default value to a variable when it may not have been set due to nullity. For example, if you have a variable that may contain a nullable integer, you can use the Null-Coalescing operator to ensure that if it is null, a predefined default value (like 0) is used instead, making your code more robust and reducing the likelihood of null reference exceptions. In contrast, the other choices relate to different functionalities in C# programming: combining delegates pertains to event handling, creating event handlers involves a different use of delegates, and handling exceptions requires try-catch blocks. These concepts do not align with the specific purpose of the Null-Coalescing operator, which focuses solely on providing default values for nullable types.