Jagged arrays
Learn flexible row structures with arrays of arrays (jagged).
Jagged arrays
An array whose rows may have different sizes is called a jagged array. Its type is int[][]; literally 'array of arrays'. int[][] rows = new int[3][]; creates a jagged array with three rows.
Each row is a separate array; for example rows[0] = new int[] { 1, 2 }; makes the first row two elements. int[,] keeps every row the same size, while int[][] allows flexible row lengths.
Jagged initialization and access
You can also initialize a jagged array in one line: int[][] rows = { new int[] { 1, 2 }, new int[] { 3, 4, 5 } };. The first row has two, the second three elements.
Access uses two separate brackets: rows[1][2] gives the second row's third element. rows.Length is the row count and rows[i].Length the length of row i.
Exercise Declare a jagged array and print a cell
Declare a jagged array rows with the value { new int[] { 1, 2 }, new int[] { 3, 4, 5 } }. Then print rows[1][2] with Console.WriteLine. The output should be 5.
Show example solution
Write int[][] rows = { new int[] { 1, 2 }, new int[] { 3, 4, 5 } }; and print it with Console.WriteLine(rows[1][2]);
Example solution:
using System;
class Program
{
static void Main()
{
int[][] rows = { new int[] { 1, 2 }, new int[] { 3, 4, 5 } };
Console.WriteLine(rows[1][2]);
}
}Test yourself
-
Write the jagged array type
int____ rows = new int[3][];Show answer
int[][] rows = new int[3][]; -
Match each type to its meaning
- int[][]
- Jagged array
- int[,]
- Matrix (rectangular)
- new int[3][]
- Three-row jagged
- rows[0]
- First row array
-
Which is a jagged array (rows of different sizes)?
// which one?- int[,] m
- int[] nums
- int[][] rows
- int n
Show answer
int[][] rows — Correct. int[][] is an 'array of arrays' where each row may have a different size.