C# 13.0: params Improvements

It's another exciting time of the year when Microsoft Build is happening, a lot of exciting announcements.

In this post, let's have a look at a C# 13.0 feature that is now available with the latest Visual Studio 2022 Version 17.11 Preview 1.

C# 13.0 is supported on .NET 9. To try this feature, make sure you are using the preview language version.

<Project Sdk="Microsoft.NET.Sdk">
 
  <PropertyGroup>
    <OutputType>Exe</OutputType>
    <TargetFramework>net9.0</TargetFramework>
    <LangVersion>preview</LangVersion>
  </PropertyGroup>
 
</Project>

Prior to C# 13.0, when we are using params, the parameter must be a single-dimensional array, something like follows:

void DoSomething(params string[] items)
{
    // do something with items
}

And we can call it as follows:

DoSomething("apple", "orange"); // comma separated list
DoSomething(["apple", "orange"]); // array
DoSomething(); // empty, the length of the params list is zero

With C# 13.0, params parameter type can be any recognized collection type, like List<T>, Span<T>, IEnumerable<T>, etc. You can even use your own collection types if they follow special rules.

So from C# 13.0, the following is totally valid.

void DoSomething(params IEnumerable<string> items)
{
    // do something with items
}

That's pretty cool.

If you still haven't registered for Microsoft Build 2024, you are still not late. Register now for free and access all the exciting content.

Happy Coding.

Regards,

Jaliya