Lecture 82:- 2D Arrays

A 2D array, also known as a two-dimensional array, is an array of arrays. It is a data structure that represents a table or a grid with rows and columns. Each element in a 2D array is identified by its row and column indices.

In programming, a 2D array is typically implemented as an array of arrays, where each inner array represents a row of the table or grid. This allows for storing and accessing data in a tabular format.

Here are some key points about 2D arrays:

1. Declaration: To declare a 2D array, you specify the number of rows and columns it should have. The syntax for declaring a 2D array may vary depending on the programming language. Here's an example in Java:

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// Declare a 2D array with 3 rows and 4 columns int[][] matrix = new int[3][4];

1. Accessing Elements: Elements in a 2D array can be accessed using their row and column indices. The indices start from 0. For example, to access an element at row i and column j, you would use matrix[i][j].
2. Initialization: You can initialize the elements of a 2D array during declaration or assign values later using nested loops. Here's an example in Python:

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# Initialize a 2D array with values matrix = [[1, 2, 3],          [4, 5, 6],          [7, 8, 9]]

1. Size: The size of a 2D array is determined by the number of rows and columns. You can obtain the number of rows using matrix.length (Java) or len(matrix) (Python), and the number of columns using matrix[0].length (Java) or len(matrix[0]) (Python).
2. Iteration: You can iterate over the elements of a 2D array using nested loops, iterating over the rows and columns. This allows you to perform operations on each element or access the entire array.
3. Multidimensional Operations: 2D arrays support various operations such as sorting, searching, and matrix operations like addition, multiplication, and transposition, depending on the programming language and available libraries.

2D arrays are useful for representing and manipulating data in a grid-like structure. They are commonly used for tasks such as representing matrices, game boards, images, or any tabular data that requires rows and columns.