Jagged Arrays

Part of the Logic & Flow section of Coddy's C# journey — lesson 5 of 66.

Jagged arrays in C# are arrays of arrays, where each inner array can have a different length.

Create a jagged array with 3 rows:

int[][] jaggedArray = new int[3][];

Initialize each row with different lengths:

jaggedArray[0] = new int[4]; // First row has 4 elements
jaggedArray[1] = new int[2]; // Second row has 2 elements
jaggedArray[2] = new int[5]; // Third row has 5 elements

Assign values to elements:

jaggedArray[0][0] = 10;
jaggedArray[1][1] = 20;
jaggedArray[2][3] = 30;

Initialize a jagged array with values:

int[][] numbers = new int[][]
{
    new int[] {1, 2, 3, 4},
    new int[] {5, 6},
    new int[] {7, 8, 9, 10, 11}
};

Get the number of rows:

int rows = jaggedArray.Length; // Returns 3

Get the length of a specific row:

int elementsInRow1 = jaggedArray[1].Length; // Returns 2

Challenge

Medium

Create a method called createTriangle that:

Takes a positive integer size as a parameter
Returns a jagged array representing a triangle pattern
Each row should have one more element than the previous row
Each element should be equal to its row index plus its column index

For example, with size = 4, the jagged array should be:

[0]
[1, 2]
[2, 3, 4]
[3, 4, 5, 6]

Cheat sheet

Jagged arrays are arrays of arrays where each inner array can have different lengths.

Create a jagged array:

int[][] jaggedArray = new int[3][];

Initialize rows with different lengths:

jaggedArray[0] = new int[4]; // First row has 4 elements
jaggedArray[1] = new int[2]; // Second row has 2 elements
jaggedArray[2] = new int[5]; // Third row has 5 elements

Assign values to elements:

jaggedArray[0][0] = 10;
jaggedArray[1][1] = 20;
jaggedArray[2][3] = 30;

Initialize with values directly:

int[][] numbers = new int[][]
{
    new int[] {1, 2, 3, 4},
    new int[] {5, 6},
    new int[] {7, 8, 9, 10, 11}
};

Get array dimensions:

int rows = jaggedArray.Length; // Number of rows
int elementsInRow1 = jaggedArray[1].Length; // Length of specific row

Try it yourself

public class CreateTriangle
{
    // Implement the CreateTriangle method
    public static int[][] createTriangle(int size)
    {
        // Write your code here
        
    }
}

Test yourself

This lesson includes a short quiz. Start the lesson to answer it and track your progress.

All lessons in Logic & Flow

1Multi-dimensional Arrays

2D Arrays Basics Declaring and Initializing 2D Accessing 2D Array Elements Nested Loops with 2D ArraysJagged ArraysCommon Matrix Operations Recap - Multi-dimensional

4Flow Control Techniques

Early Returns Guard Clauses Jump Statements (goto)Break and Continue Flatten Nested Conditionals

7Logical Operators Advanced

Short-Circuit Evaluation Conditional Logical Operators Operator Precedence Recap - Advanced Operators

10HashMap Part 2

HashMap Methods Nested HashMap Recap - Manage Warehouse Recap - HashMap Operations