Microsoft Certified Solutions Developer (MCSD) Certification Practice Test

What does Unboxing refer to in C#?

1. Taking an object and converting it into a value type

2. Defining a new data type

3. Creating a delegate

4. Returning an interface

The correct answer is: Taking an object and converting it into a value type

Unboxing in C# refers specifically to the process of taking an object that is of a reference type (typically an object that is boxed) and converting it back into its corresponding value type. Boxed types are instances of value types that are stored on the managed heap. When a value type, such as an int or a struct, is boxed, it is wrapped in an object so that it can be treated as a reference type. Unboxing is necessary when you want to retrieve the original value from the boxed object, allowing you to work with it as a value type again. This process is significant because it involves type checking and demands a cast to ensure that the type being unboxed matches the original value type that was boxed. The other options do not accurately describe what unboxing entails: defining a new data type refers to creating custom types, creating a delegate involves defining a method signature for callback functions, and returning an interface involves implementing a contract that defines a set of methods. These concepts are unrelated to the process of converting a boxed object back into its original value type.