What are the characteristics and uses of C# structures?

C# struct is a custom value type data structure with the following characteristics and uses:

1. Value type: Structures are a type of value type, where their instances are directly stored on the stack instead of on the heap. This makes the creation and destruction of structures more efficient than classes (reference types).
2. Lightweight: Structures are typically more lightweight than classes because they do not support features such as inheritance, destructors, and finalizers. Structures are mainly used to represent simple data types like coordinates, colors, dates, etc.
3. Value semantics: structs have value semantics, which means that when they are assigned or passed, a complete copy of the data is made. This is different from classes, where assignment and passing have reference semantics, meaning that a reference is copied rather than the data itself.
4. Default values for value types: When a struct is created, the member variables are automatically initialized to their corresponding default values. For example, member variables of integer type default to 0, and member variables of boolean type default to false.
5. Structures can implement interfaces, allowing them to exhibit similar behaviors as classes, such as defining methods, properties, and indexers.
6. Suitable for small data: Since instances of structures are stored on the stack, using structures may lead to a decrease in performance for large data or situations that require frequent copying.

Structures are primarily used to provide performance advantages in cases where only a small amount of data needs to be encapsulated. For example, structures can be used to represent simple data types such as 2D coordinates, colors, vectors, etc. Additionally, structures are often used to create immutable data types since their values cannot be modified.