Range

Modern versions of the C# language support Range syntax. We can specify a range of indexes and then access an array or List with that range.

With two dots, we indicate we want all indexes between the first and second numbers. We can also specify "all indexes" from the start or the end.

Example

Here we create 4 ranges that all cover the same indexes in the array. We skip over the first element, but include the second, third and fourth (final) indexes.

using System;

int[] values = [0, 1, 600, 610];

// Version 1: create a range.
Range r = 1..values.Length;
int[] test0 = values[r];
foreach (int v in test0)
{
    Console.WriteLine($"test0: {v}");
}

// Version 2: use indexes from the end with caret.
int[] test1 = values[1..values.Length];
foreach (int v in test1)
{
    Console.WriteLine($"test1: {v}");
}

// Version 3: omit end index to get maximum value.
int[] test2 = values[1..];
foreach (int v in test2)
{
    Console.WriteLine($"test2: {v}");
}

// Version 4: use "from end" syntax with caret.
int[] test3 = values[1..^0];
foreach (int v in test3)
{
    Console.WriteLine($"test3: {v}");
}
test0: 1
test0: 600
test0: 610
test1: 1
test1: 600
test1: 610
test2: 1
test2: 600
test2: 610
test3: 1
test3: 600
test3: 610

Ranges are useful when accessing elements from arrays and Lists. We can use the modern range syntax to simplify programs that access elements from within these linear collections.