C# Default Parameters

Question

This is, probably, a very simple answer for someone. I have a method with an Optional Parameter like so;

public static Email From(string emailA         


        

Answer 1

Optional parameters have been supported in the CLR since 1.0. Languages like VB.Net's have been using them since the start. While the first version of C# to support them is 4.0, it can still generate valid code for a 2.0 CLR and in fact does so. Hence you can use default parameters in 2010 if you are targeting the 3.5 CLR (or 2.0, 3.0, etc ...)

This type of support is not limited to default parameters. Many new C# features can be used on older version of the framework because they do not rely on CLR changes. Here are a few more which are supported on CLR versions 2.0 and above

• Named Arguments: Added C# 4.0
• Lambda Expressions: Added C# 3.0
• Auto Properties: Added C# 3.0
• Extension Methods: Added C# 3.0
• Co/Contra Variance: Added C# 4.0