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C# Arrays (With STEP-BY-STEP Videos)

Codebuns — Sun, 12 Mar 2023 15:12:04 +0000

C# Arrays tutorial has related videos. Watch it with the written material for a STEP-BY-STEP explanation with CODE examples. Videos will reduce your learning curve and deepen your understanding where you’re uncertain: C# Single Dimensional Array | C# Rectangular Array | C# Jagged Array

What Is an Array?

Array is a data structure that stores multiple values of the same type in a single variable. You access each individual value through an integer index with an array name. Arrays can be of different dimensions like Single-dimension, Multi-dimension or Jagged array. The simplest of all is Single dimension, so you’ll start learning how to declare, initialize, and use single dimensional array.

What Is Single-Dimensional Array?

The below image shows a C# single-dimensional array of eight integers, which contains array elements from 0 to 7. Array’s smallest and largest indexes are called its lower and upper bound, respectively. The lower bound is always 0, and the upper bound is always one less than the length of the array (arrayLength – 1). That means if an array has eight elements, their indices are 0, 1, 2, 3, 4, 5, 6, and 7.

Arrays also have GetLowerBound and GetUpperBound methods that return the lower and upper bounds for a particular dimension in an array.

Note: if you use an index that’s greater than the upper bound, an IndexOutOfRangeException will be thrown.

Edit and test all the CODE examples used in this article with C# online editor: Single-Dimensional Array Code Playground

Declare and Initialize One-Dimensional Array in C#.

You can create an array using either one or two statements.

Using Two Statements

An array is declared by defining the type of elements inside the array, followed by empty square brackets [ ] and a variable name.

Syntax

type[] arrayName; // declaration: initial value is null

Example

int[] integerValues;

However, the above statement only declares the variable. It does not yet initialize an array. You do the initialization part with the new keyword, followed by the data type and a second set of square brackets containing the length or size of the array.

Syntax

arrayName = new type[arrayLength]; // initialization: Creates an array object.

Example

integerValues = new int[4];

Using One Statement

Declaration and initialization of an array simultaneously on a single line.

Syntax

type[] arrayName = new type[arrayLength]; // declaration & initialization

Example

int[] integerValues = new int[4];

Create and Assign Values to One-Dimensional Array

You can reference array elements using an index inside square brackets, one at a time, and then assign values, as shown below. The index of the first element always starts with 0.

int[] integerValues = new int[4];
integerValues[0] = 1;
integerValues[1] = 2;
integerValues[2] = 3;
integerValues[3] = 4;

You can use another method, which is quite convenient. With this method, values can be assigned simultaneously using CURLY BRACKET {…} NOTATION. This syntax is valid when creating an array of a known size and wants to specify the initial values quickly.

int[] integerValues = { 1, 2, 3, 4 };

You can also use the var keyword with an array to declare a variable that infers its type from its assigned value. Use new keyword when using this approach.

var integerValues = new[] { 1, 2, 3, 4 };

Update One-Dimensional Array Value

You can access a value of an indexed array element by using an indexer ([ ]) and then assign a value to it.

integerValues[1] = 20;

Above statement assigns a value 20 to the 2nd column with an index ([1]), which updates the value from 2 to 20.

integerValues[3] = 40;

The above statement assigns a value of 40 to the 4th column with an index ([3]), which updates the value from 4 to 40.

Access One-Dimensional Array Values

You can retrieve a specific value in the array using an index position inside the square brackets [ ]. Access array elements using 0, 1, 2, and 3 indexes.

Syntax

arrayName[index];

Example

Console.WriteLine(integerValues[1]); // return 2

The above statement gets the value 2 from the 2nd column with an index [1].

Console.WriteLine(integerValues[3]); // return 4

The above statement gets the value 4 from the 4th column with an index [3].

There are two kinds of multi-dimensional arrays: Rectangular and Jagged.

What Is Rectangular Array in C#?

C# rectangular array is an array of two (or more) dimensions separated by a COMMA. You can think of a rectangular array as a table, where the first dimension is the number of rows, and the second dimension is the number of columns keeping in mind that every row is the same length. Due to 2 dimensions, it’s also known as a two-dimensional or 2D array.

Edit and test all the CODE examples used in this article with C# online editor: Rectangular Array Code Playground

Declare and Initialize Rectangular Array in C#.

You can create an array using either one or two statements.

Using Two Statements

On the left side of the declaration, you need a data type, the type of values in the array like it will hold integer values, decimal, string etc. Followed by COMMA (,) within the set of BRACKETS([ ]). The comma indicates that the array has two dimensions. Two or more commas would indicate three or more dimensions.

Syntax

type[,] arrayName;

Example

int[,] intArray;

A new keyword creates an array on the right side of instantiation. You specify the number of ROWS in the array, followed by a COMMA, and then the number of COLUMNS to set the size of each dimension in the array.

Syntax

arrayName = new type[rows, columns]; // 2D array

type[,] indicates 2D array
type[rows, columns] indicates size of ROW and COLUMN.

Example

intArray = new int[3, 2];

Note: Multi-dimensional array is indexed by two or more integers.

Using One Statement

Declaration and initialization of an array simultaneously on a single line.

Syntax

type[,] arrayName = new type[rows, columns];

Example

int[,] intArray = new int[3, 2];

Create and Assign Values to a Rectangular Array

Array elements can be referenced using two integers with an indexer, one statement at a time to assign values to the elements of the intArray as shown below.

int[,] intArray = new int[3, 2];
intArray[0, 0] = 1;
intArray[0, 1] = 2;
intArray[1, 0] = 3;
intArray[1, 1] = 4;
intArray[2, 0] = 5;
intArray[2, 1] = 6;

There’s a shorter form below.

int[,] intArray = { { 1, 2 }, { 3, 4 }, { 5, 6 } };

DEV Community: Codebuns

C# Arrays (With STEP-BY-STEP Videos)

What Is an Array?

What Is Single-Dimensional Array?

Declare and Initialize One-Dimensional Array in C#.

Using Two Statements

Syntax

Example

Syntax

Example

Using One Statement

Syntax

Example

Create and Assign Values to One-Dimensional Array

Update One-Dimensional Array Value

Access One-Dimensional Array Values

Syntax

Example

What Is Rectangular Array in C#?

Declare and Initialize Rectangular Array in C#.

Using Two Statements

Syntax

Example

Syntax

Example

Using One Statement

Syntax

Example

Create and Assign Values to a Rectangular Array

Access Individual Rectangular Array Values

Syntax

Example

Accessing Rectangular Array Values Using Nested for Loops

3 by 2 Array Example

OUTPUT

What Is a Jagged Array in C#?

Declare and Initialize a Jagged Array in C#.

Using Two Statements

Syntax

Syntax

Using One Statement

Syntax

Create a Jagged Array

Assign Values to a Jagged Array

Access Individual Values of a Jagged Array

Syntax

Example

Syntax

Example

OUTPUT

Jagged Array vs Multidimensional Array

C# Reference | Microsoft Docs

C# for Loop (With STEP-BY-STEP Video)

The for Loop

Syntax

Execution Order

Flowchart

Example: C# for Loop

Variations of for Loop

The break Keyword With for Loop

The continue Keyword With for Loop

Infinite for Loop

Nested for Loops

Difference Between for Loop and while Loop

Array with for Loop

List With for Loop

C# Jagged Array (With STEP-BY-STEP Video)

Declaration and Instantiation of a Jagged Array

Create and Assign Values to a Jagged Array

Access Individual Array Elements

Example 1: Jagged Array with 3 Rows of Different Lengths

Example 2: Jagged Array with 2 Rows of Different Lengths

Array of Strings

Example 3: Jagged Array with 2 Rows, Each of Which Contains Multi-Dimensional Array

Jagged Array Property and Method

Processing Jagged Array Using Nested for Loops

Example 1: Jagged Array with 3 Rows of Different Lengths

Example 2: Array with 2 Rows of Different Lengths

Example 3: Loop Through Jagged Array Composed of Multi-Dimensional Arrays

Jagged Array in Short