Arrays

Syntax

type[] arrayName = new type[size];

Examples

int[] numbers = { 10, 20, 30, 40, 50 };
string[] names = new string[3];
names[0] = "Fola";
names[1] = "Zain";
names[2] = "Jamal";

Console.WriteLine(numbers[0]);    // 10
Console.WriteLine(numbers.Length); // 5
Console.WriteLine(names[1]);       // Zain

int[] scores = { 85, 92, 78, 90 };

for (int i = 0; i < scores.Length; i++)
{
    Console.WriteLine($"Index {i}: {scores[i]}");
}

// foreach - simpler when you don't need the index
foreach (int score in scores)
{
    Console.WriteLine(score);
}

int[,] grid = {
    { 1, 2, 3 },
    { 4, 5, 6 }
};
Console.WriteLine(grid[1, 2]);  // 6 (row 1, column 2)

int[][] jagged = new int[2][];
jagged[0] = new int[] { 1, 2, 3 };
jagged[1] = new int[] { 4, 5 };  // different length - that's allowed
Console.WriteLine(jagged[1][1]);  // 5

int[] numbers = { 5, 2, 8, 1, 9 };

Array.Sort(numbers);
Console.WriteLine(string.Join(", ", numbers));  // 1, 2, 5, 8, 9

Array.Reverse(numbers);
Console.WriteLine(string.Join(", ", numbers));  // 9, 8, 5, 2, 1

int index = Array.IndexOf(numbers, 5);
Console.WriteLine(index);  // 2

Best practices

• Use a List<T> instead of a plain array whenever the collection needs to grow or shrink dynamically
• Use foreach when you just need the values, and a standard indexed for loop when you need the index too
• Use string.Join() to print array contents readably - printing an array directly with WriteLine() shows its type name, not its contents
• Prefer jagged arrays (int[][]) over true multi-dimensional arrays (int[,]) when rows might have different lengths - jagged arrays are also generally faster in C#

At a glance

Purpose

Applications on the .NET platform

File extension

.cs

Runs in

.NET runtime

Usually used with

.NET SDK and libraries

Specifications & further reading

• C# language reference

Related C# documentation