Examples of Immutable Types in .Net

Question

We know the concept of immutability but need to know few immutable types other than

• String
• DateTime

Are there more?

Answer 1

Some examples from mscorlib:

• All of the primitive types
• enums
• decimal
• (U)IntPtr
• DateTime, DateTimeOffset, TimeSpan
• KeyValuePair<,> - as an opposite, DictionaryEntry is not immutable
• Tuple<...>
• (Multicast)Delegate - similarly to strings, always a new instance is returned when it is changed.
• Guid
• Version

Interestingly, string is actually not really immutable; however, we can treat it as a "practically immutable" type, meaning, that the content of a string instance cannot be changed by the public ways (at least, in a safe context). But it has for example a wstrcpy internal method, which is used by the StringBuilder class to manipulate a string instance.