Programming_Basics

Data Structures

A data structure is a storage that is used to store and organize data. It is a way of arranging data on a computer so that it can be accessed and updated efficiently. Most essential and responsible for organizing, processing, accessing, and storing data efficiently.

Types of Data Structures

Data Structures are divided based on how they are arranged in the memory

1. Linear Data Structures
2. Non-Linear Data Structures

Linear Data Sturctures

Data elements are arranged sequentially or linearly, where each element is attached to its previous and next adjacent elements. Examples: Arrays, Queue, Stack

Non Linear Data Structures

Data structures where data elements are not placed sequentially or linearly are called non-linear data structures. Examples: Trees, Graphs

Arrays

An array is a collection of homogenous data type. A collection of items stored at contiguous memory locations. Each item in an array is indexed starting with 0.

Array Declaration

/* Static Arrays are arrays that are declared before runtime
and are assigned values while writing the code.
*/

// The syntax of declaring a static array is:
<data type><variable name>[]
	= {<data1>, <data2>,…..<dataN> };

// Example:
int arr[] = { 2, 5, 6, 9, 7, 4, 3 };

Access the Array

Array is accessed by referring to index number

String[] cars = {"Volvo", "BMW", "Ford", "Mazda"};
System.out.println(cars[0]);
// Outputs Volvo

Changing the Array Element

String[] cars = {"Volvo", "BMW", "Ford", "Mazda"};
cars[0] = "Opel";
System.out.println(cars[0]);
// Now outputs Opel instead of Volvo

Loop through the Array

1. Using ‘for’ loop Example:

   String[] cars = {"Volvo", "BMW", "Ford", "Mazda"};
   for (int i = 0; i < cars.length; i++) {
     System.out.println(cars[i]);
   }
   

2. Using ‘for-each’

   for (type variable : arrayname) {
     ...
   }
   

   Example:

   String[] cars = {"Volvo", "BMW", "Ford", "Mazda"};
   for (String i : cars) {
     System.out.println(i);
   }
   

   Additional Reference

   Here’s a video overview of arrays

Exercise

Now try it for yourself by completing Arrays Exercise