Can you use optional parameters in code targeting .NET 3.5?

Question

I\'m looking to write a library that uses the new optional parameters feature of C# 4.0, but I want to target it to the 3.5 version of the framework. Is this possible?

Answer 1

You can use optional and named parameters in a targeted framework of a previous version as long the assemblies are build within a development environment for v4 (f.e. VS2010). But you should be aware of runtime compiling or publishing websites in this case the compiler of the targeted framework will be used. And because the compilers of the older frameworks doesn't understand the syntax of optional and named params it will results in compiler errors.