C# Core Types and Memory Model

Distinguish value types (struct, enum) from reference types (class, delegate, interface) in C# and explain their memory allocation differences (stack vs. heap).

Explain boxing and unboxing and their performance implications.

Define and use structs, including when to prefer structs over classes for performance.

Define and use enums, including the [Flags] attribute for bitwise combinations.

Use nullable value types (Nullable<T> and the ? shorthand syntax).

Perform type checking and casting using the `is` and `as` operators.

Use string interpolation and verbatim strings for effective string formatting.