Starting from C# 12 you may use the [Collection Expressions][1] and *spread operator* `..`, for example: ``` int[] a = [1, 2, 3]; int[] b = [4, 5, 6]; int[] c = [..a, ..b]; ``` **Note1:** Although I'm not certain about its efficiency at the moment, it's definitely the most concise and easiest approach.
**Note2:** The feature is available only in preview mode, but its official release is planned for Nov 2023.
[1]: https://learn.microsoft.com/en-us/dotnet/csharp/whats-new/csharp-12#collection-expressions

Starting from C# 12 you may use the [Collection Expressions][1] and *spread operator* `..`, for example: ``` int[] a = [1, 2, 3]; int[] b = [4, 5, 6]; int[] c = [..a, ..b]; ```
**Note:** The feature is available only in preview mode, but its official release is planned for Nov 2023.
[1]: https://learn.microsoft.com/en-us/dotnet/csharp/whats-new/csharp-12#collection-expressions