//语法糖Range
static void Main(string[] args)
{
    var myArray = new string[]
    {
        "Item1",
        "Item2",
        "Item3",
        "Item4",
        "Item5"
    };
    for(int i=1; i <= 3; i++)
    {
        Console.WriteLine(myArray[i]);
    }
    foreach (var item in myArray[1..4])
    {
        Console.WriteLine(item);
    }
    foreach (var item in myArray[1..])
    {
        Console.WriteLine(item);
    }
    foreach (var item in myArray[..3])
    {
        Console.WriteLine(item);
    }
    foreach (var item in myArray[..])
    {
       Console.WriteLine(item);
    }
    foreach (var item in myArray[1..^1])
    {
        Console.WriteLine(item);
    }
    Console.ReadLine();
}

static void Main(string[] args)
{
    var myArray = new string[]
    {
        "Item1",
        "Item2",
        "Item3",
        "Item4",
        "Item5"
    };
 
    Range range = 1..4;
 
    foreach (var item in myArray[range])
    {
        Console.WriteLine(item);
    }
 
    Console.ReadLine();
}

Console.WriteLine("123456789"[1..4]);