What is jagged array?

A jagged array is an array of arrays. 
 



Let us understand jagged array with an example
1. There are 3 employees - Mark, Matt, John
2. Mark has a bachelor, master and doctorate degree (3 qualifications)
3. Matt has only a bachelor degree (1 qualification)
4. John has a bachelor and a master degree (2 qualifications)

Different employees have different number of qualifications. To store their qualifications in a data structure, Jagged array is one of the choices.

public class Program
{
    public static void Main()
    {
        // Create a string array to store the names of the employees
        string[] employeeNames = new string[3];
        employeeNames[0] = "Mark";
        employeeNames[1] = "Matt";
        employeeNames[2] = "John";

        // Create a jagged array. As we want to store varying number of qualifications 
        // and as qualifications are strings, let's create an array of string arrays.
        string[][] jaggedArray = new string[3][];

        // Set the size of the first string array to 3, as we want to store 3 qualifications for Mark
        jaggedArray[0] = new string[3];
        // Set the size of the second string array to 1, as we want to store 
        // only 1 qualification for Matt
        jaggedArray[1] = new string[1];
        // Set the size of the third string array to 2, as we want to store 2 qualifications for John
        jaggedArray[2] = new string[2];

        // Set the values for the first string array
        jaggedArray[0][0] = "Bachelor";
        jaggedArray[0][1] = "Master";
        jaggedArray[0][2] = "Doctorate";
        // Set the values for the second string array
        jaggedArray[1][0] = "Bachelor";
        // Set the values for the thrid string array
        jaggedArray[2][0] = "Bachelor";
        jaggedArray[2][1] = "Master";

        // Loop thru and print out the elements of Jagged array
        for (int i = 0; i < jaggedArray.Length; i++)
        {
            Console.WriteLine(employeeNames[i]);
            Console.WriteLine("--------");
            string[] innerArray = jaggedArray[i];
            for (int j = 0; j < innerArray.Length; j++)
            {
                Console.WriteLine(innerArray[j]);
            }
            Console.WriteLine();
        }
    }
}

In this example, we have created an array of string arrays. In a similar way, we create an array of integer arrays, an array of decimal arrays etc.