Store and manage data with arrays
An array is a fixed-size, ordered collection of values that all share the same type. Arrays are one of the most fundamental data structures in C# because they store multiple related values under a single variable name.
Creating an array
You can create an array using curly braces to list its initial values, or by specifying its size up front.
string[] colors = { "red", "green", "blue" };
int[] scores = new int[4];
The first line creates an array of three strings. The second line creates an array that can hold four integers, each starting at the default value of 0.
Accessing items by index
Each item in an array has a numbered position called an index, starting at 0.
string[] colors = { "red", "green", "blue" };
Console.WriteLine(colors[0]); // Output: red
Console.WriteLine(colors[2]); // Output: blue
The fixed size of an array
An array's size is set when you create it and can't change afterward. You can update the value at an existing index, but you can't add or remove items.
string[] colors = { "red", "green", "blue" };
colors[0] = "purple"; // Replaces "red" with "purple"
Console.WriteLine(colors[0]); // Output: purple
Console.WriteLine(colors.Length); // Output: 3
If you need to store more or fewer items than an array's fixed size allows, you need to create a new array, or use a different collection type, like a List<T>.
Tip
Choose plural, descriptive array names, like scores or colors, so it's clear at a glance that the variable holds multiple items rather than one.
Iterating over an array
Arrays work naturally with foreach loops, which step through every item without you having to manage an index yourself.
int[] scores = { 95, 82, 76, 91 };
foreach (int score in scores)
{
Console.WriteLine(score);
}
Output:
95
82
76
91