Microsoft Certified Solutions Developer (MCSD) Certification Practice Test

What defines an anonymous type in C#?

1. It is declared with a formal class definition.

2. It uses object initializers without a formal class definition.

3. It requires explicit type declaration.

4. It cannot have properties.

The correct answer is: It uses object initializers without a formal class definition.

An anonymous type in C# is defined by its use of object initializers without a formal class definition. This feature allows developers to create an object on the fly, typically when they need a simple data structure to hold a set of values without the overhead of creating a separate class. Anonymous types are particularly useful in situations where you want to encapsulate a few related values together quickly, such as when working with LINQ queries. Since the type does not require a declared class, the compiler generates a new type in the background that has read-only properties, which can be accessed easily after creation. The focus on using object initializers highlights the convenience of anonymous types. Developers can specify property names and assign values to them directly when creating an instance, thus eliminating the need for boilerplate code associated with class definitions. This feature is especially beneficial in scenarios such as data querying and transforming data structures on-the-fly.