Arrays and Collections

C# in Visual Studio 2026 — a hands-on guide for developers at every level.

Arrays

An array stores a fixed number of elements of the same type. The size is set at creation and cannot change.

// Declare and initialise
int[] scores = { 85, 92, 78, 96, 88 };

// Access by index (zero-based)
Console.WriteLine(scores[0]);  // 85
Console.WriteLine(scores[^1]); // 88 (last element, C# 8+)

// Length
Console.WriteLine(scores.Length); // 5

Array Methods

Array.Sort(scores);
Array.Reverse(scores);
int idx = Array.IndexOf(scores, 92);
Console.WriteLine($"92 is at index {idx}");

Multi-Dimensional Arrays

// 2-D array (3 rows, 3 cols)
int[,] grid = {
    { 1, 2, 3 },
    { 4, 5, 6 },
    { 7, 8, 9 }
};
Console.WriteLine(grid[1, 2]); // 6

Ranges and Slices (C# 8+)

int[] nums = { 10, 20, 30, 40, 50 };
int[] slice = nums[1..4];   // { 20, 30, 40 }
int[] last2 = nums[^2..];   // { 40, 50 }