“const correctness” in C#

Question

The point of const-correctness is to be able to provide a view of an instance that can\'t be altered or deleted by the user. The compiler supports this by pointing out when

Answer 1

• The const keyword can be used for compile time constants such as primitive types and strings
• The readonly keyword can be used for run-time constants such as reference types

The problem with readonly is that it only allows the reference (pointer) to be constant. The thing referenced (pointed to) can still be modified. This is the tricky part but there is no way around it. To implement constant objects means making them not expose any mutable methods or properties but this is awkward.

See also Effective C#: 50 Specific Ways to Improve Your C# (Item 2 - Prefer readonly to const.)