Bits of .NET

Index from End (^)

var numbers = new[] { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 };

// Old way: Last element
var last = numbers[numbers.Length - 1];

// New way: ^1 means "1 from end"
var last = numbers[^1];  // 9

// Second from end
var secondLast = numbers[^2];  // 8

// Third from end
var third = numbers[^3];  // 7

Range Slicing (..)

var numbers = new[] { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 };

// First 3 elements
var first3 = numbers[0..3];  // { 0, 1, 2 }

// Skip first 3, get rest
var rest = numbers[3..];  // { 3, 4, 5, 6, 7, 8, 9 }

// Last 3 elements
var last3 = numbers[^3..];  // { 7, 8, 9 }

// Everything except last 2
var allButLast2 = numbers[..^2];  // { 0, 1, 2, 3, 4, 5, 6, 7 }

// Middle elements (skip first 2 and last 2)
var middle = numbers[2..^2];  // { 2, 3, 4, 5, 6, 7 }

// All elements (copy)
var copy = numbers[..];

// String slicing
string text = "Hello, World!";
var hello = text[..5];  // "Hello"
var world = text[7..^1];  // "World"

// List slicing
var items = new List { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 };
var firstHalf = items[..5];  // { 1, 2, 3, 4, 5 }

// Pagination
int page = 2;
int pageSize = 3;
var pageItems = items[(page * pageSize)..((page + 1) * pageSize)];

// Remove header and footer
var lines = File.ReadAllLines("data.txt");
var dataOnly = lines[1..^1];  // Skip first and last line

“CSV parsing code was full of substring calculations. Switched to ranges. Code is 50% shorter, infinitely more readable. No more off-by-one errors.”