Dev Blog

Summary ​

Conclusions ​

Structures are value types: assignment copies all fields, so they suit small immutable values, and readonly struct prevents mistakes with modifying copies. Converting a structure to object or an interface performs boxing. Records generate value equality, ToString, copying with a with expression, and deconstruction; record class is a reference type, and record struct is a value type. Enumerations replace “magic numbers” with named constants, and [Flags] lets you store sets of values in bits; together with the switch expression, they implement finite state machines. Tuples group several values without declaring a type and are convenient for returning several results from a method; deconstruction and positional patterns simplify working with them.

Self-check questions ​

  1. How does a structure differ from a class?
  2. What happens when a structure variable is assigned?
  3. What values do the fields of a structure’s default have? Is a constructor called?
  4. When should you choose a structure instead of a class?
  5. What is a readonly struct? Why are mutable structures dangerous?
  6. What are boxing and unboxing? When do they happen for structures?
  7. What members does the compiler generate for a record?
  8. How does record equality work?
  9. What is the with expression for?
  10. How does record struct differ from readonly record struct?
  11. What is the underlying type of an enumeration, and what values do its constants have by default?
  12. How do you safely parse a string into an enumeration value?
  13. How do you declare and use a flag enumeration?
  14. What is a tuple? How do you name its elements?
  15. What is deconstruction? How do you implement it for your own class?
  16. What are a positional pattern and a property pattern?