Microsoft Certified Solutions Developer (MCSD) Certification Practice Test

How do you define a new value type in C#?

1. You use the class keyword

2. You use the value keyword

3. You use the struct keyword

4. You use the enum keyword

The correct answer is: You use the struct keyword

In C#, a new value type is defined using the struct keyword. Value types in C# are types that hold their value directly, as opposed to reference types, which store a reference to the actual data. When you declare a struct, you are creating a new composite data type that encapsulates related data and can include methods, fields, properties, and events. Structs are suitable for small, simple data structures that are intended to be lightweight. An important aspect of structs is that they are allocated on the stack, which generally makes them more efficient for certain scenarios compared to reference types, which are stored in the heap. Other options involve different types of type definitions. For example, the class keyword is used to define reference types, which behave differently from value types in terms of memory allocation and object lifecycle. The value keyword does not exist in C# type definitions. The enum keyword is specifically for defining a set of named constants, which is not considered a value type in the same way as struct is, even though enums are derived from the underlying integral types like int. Thus, using the struct keyword is the correct way to define a new value type in C#.