When .NET assemblies are compiled, what are the classes that have x__ in their names?

Question

For example:

• StudentRegistrationService<>c__DisplayClass1
• <>f__AnonymousType56`2
• DocShareClassification<GetErrors>d__2

I'm fairly certain that StudentRegistrationService<>c__DisplayClass1 is a closure, and <>f__AnonymousType56`2 was generated when an anonymous type was specified, but I've never seen the d__ class before. Are there any more than just these?

Answer 1

That are at compile time generated classes created by using anonymous types

Answer 2

These are classes which are generated by the C# compiler in order to support at least the following features

• Closures / Anonymous Method expressions
• Anonymous types
• Iterators

The d__2 one is likely an iterator helping class.

Answer 3

IIRC it is classes generated for iterator blocks. However you should make any assumptions about these names or rely on them - it is implementation details and may be changed in any time