using System;

public class Program

{

    public static void Main()

    {

        char fooChar = 'a';

        ReadOnlySpan<char> fooReadOnlyCharFromString = fooChar.ToString(); //will implicitly cast

        ReadOnlySpan<char> fooReadOnlyCharFromArray = new ReadOnlySpan<char>(new [] { fooChar });

        Console.WriteLine(fooReadOnlyCharFromString.ToString());

        Console.WriteLine(fooReadOnlyCharFromArray.ToString());

    }

}