What are lifted operators?

by

Lifted operators are operators which work over nullable types by “lifting” the operators which already exist on the non-nullable form. So for example, if you do:

int? x = 10;
int? y = 10;
int? z = x + y;

That “+” operator is lifted. It doesn’t actually exist on Nullable<int> but the C# compiler acts as if it does, generating code to do the right thing. (For the most case, that’s a matter of checking whether either operand is null; if so, the result is null. Otherwise, unwrap both operands to their non-nullable values, use the normal operator, and then wrap the result back into a nullable value. There are a few special cases around comparisons though.)

See section 6.4.2 (lifted conversion operators) and 7.3.7 (lifted operators) of the C# spec for more information.

More Related Contents:

  1. Nullable types and the ternary operator: why is `? 10 : null` forbidden? [duplicate]
  2. How to check if an object is nullable?
  3. What is the difference between Nullable.HasValue or Nullable != null?
  4. Nullable type is not a nullable type?
  5. What does “DateTime?” mean in C#?
  6. How to parse a string into a nullable int
  7. Why GetType returns System.Int32 instead of Nullable? [duplicate]
  8. Invalid cast from ‘System.Int32’ to ‘System.Nullable`1[[System.Int32, mscorlib]]
  9. Optional return in C#.Net
  10. Where in memory are nullable types stored?
  11. How is the boxing/unboxing behavior of Nullable possible?
  12. Are nullable types reference types?
  13. Boxing / Unboxing Nullable Types – Why this implementation?
  14. Why doesn’t the conditional operator correctly allow the use of “null” for assignment to nullable types? [duplicate]
  15. how are nullable types implemented under the hood in .net?
  16. Parse DateTime with time zone of form PST/CEST/UTC/etc
  17. Do you need to dispose of objects and set them to null?
  18. How can a Word document be created in C#? [closed]
  19. FTPS (FTP over SSL) in C#
  20. Not able to cast string to int. Error msg: Input string was not in a correct format
  21. Does List guarantee insertion order?
  22. Assigning events in object initializer
  23. How to give Read/Write permissions to a Folder during installation using .NET
  24. Are C# events synchronous?
  25. lowering priority of Task.Factory.StartNew thread
  26. Global setting for AsNoTracking()?
  27. Type result with conditional operator in C#
  28. Filetype association with application (C#)
  29. Who Disposes of an IDisposable public property?
  30. Shredding files in .NET

Leave a Comment