What are the correct version numbers for C#? What came out when? Why can't I find any answers about C# 3.5?
This question is primarily to aid those who are searching for an answer using an incorrect version number, e.g. "C# 3.5". The hope is that anyone failing to find an answer with the wrong version number will find this question and then search again with the right version number.
These are the versions of C# known about at the time of this writing:
IEnumerators which implemented
IDisposable. A few other small features.
var), query expressions
dynamic), delegate and interface generic variance, more COM support, named arguments, tuple data type and optional parameters
Addmethods in collection initializers.
There is no such thing as C# 3.5 - the cause of confusion here is that the C# 3.0 is present in .NET 3.5. The language and framework are versioned independently, however - as is the CLR, which is at version 2.0 for .NET 2.0 through 3.5, .NET 4 introducing CLR 4.0, service packs notwithstanding. The CLR in .NET 4.5 has various improvements, but the versioning is unclear: in some places it may be referred to as CLR 4.5 (this MSDN page used to refer to it that way, for example), but the
Environment.Version property still reports 4.0.xxx.
More detailed information about the relationship between the language, runtime and framework versions is available on the C# in Depth site. This includes information about which features of C# 3.0 you can use when targeting .NET 2.0. (If anyone wants to bring all of the content into this wiki answer, they're welcome to.)