Array Program in C++

#include <iostream>
using namespace std;

#include <iomanip>
using std::setw;

int main () {

   int n[ 10 ]; // n is an array of 10 integers

   // initialize elements of array n to 0       
   for ( int i = 0; i < 10; i++ ) {
      n[ i ] = i + 100; // set element at location i to i + 100
   }
   cout << "Element" << setw( 13 ) << "Value" << endl;

   // output each array element's value                   
   for ( int j = 0; j < 10; j++ ) {
      cout << setw( 7 )<< j << setw( 13 ) << n[ j ] << endl;
   }

   return 0;
}

                                                   OUTPUT:-

Array in C++

C++ provides a data structure, the array, which stores a fixed-size sequential collection of elements of the same type. An array is used to store a collection of data, but it is often more useful to think of an array as a collection of variables of the same type.

Instead of declaring individual variables, such as number0, number1, ..., and number99, you declare one array variable such as numbers and use numbers[0], numbers[1], and ..., numbers[99] to represent individual variables. A specific element in an array is accessed by an index.

All arrays consist of contiguous memory locations. The lowest address corresponds to the first element and the highest address to the last element.

Declaring Arrays:-

To declare an array in C++, the programmer specifies the type of the elements and the number of elements required by.

type arrayName [arraySize];

This is called a single-dimension array. The arraySize must be an integer constant greater than zero and type can be any valid C++ data type. For example, to declare a 10-element array called balance of type double, use this statement.

Double balance[10];

Initializing Arrays:-

You can initialize C++ array elements either one by one or using a single statement as.

double balance[] = {100.0,2.0,3.9,17.9};

The above statement assigns element number 5^th in the array a value of 50.0. Array with 4^th index will be 5^th, i.e., last element because all arrays have 0 as the index of their first element which is also called base index. 

Accessing Array Elements

An element is accessed by indexing the array name. This is done by placing the index of the element within square brackets after the name of the array.

double salary = balance [9];

Java - Basic Syntax

When we consider a Java program, it can be defined as a collection of objects that communicate via invoking each other's methods. Let us now briefly look into what do class, object, methods, and instance variables mean.

·        Object − Objects have states and behaviors. Example: A dog has states - color, name, breed as well as behavior such as wagging their tail, barking, eating. An object is an instance of a class.

·        Class − A class can be defined as a template/blueprint that describes the behavior/state that the object of its type supports.

·        Methods − A method is basically a behavior. A class can contain many methods. It is in methods where the logics are written, data is manipulated and all the actions are executed.

·        Instance Variables − Each object has its unique set of instance variables. An object's state is created by the values assigned to these instance variables.

public class MyFirstJavaProgram {

   /* This is my first java program.

    * This will print 'Hello World' as the output

    */

   public static void main(String []args) {

      System.out.println("Hello World"); // prints Hello World

   }

}

Let's look at how to save the file, compile, and run the program. Please follow the subsequent steps −

·        Open notepad and add the code as above.

·        Save the file as: MyFirstJavaProgram.java.

·        Open a command prompt window and go to the directory where you saved the class. Assume it's C:\.

·        Type 'javac MyFirstJavaProgram.java' and press enter to compile your code. If there are no errors in your code, the command prompt will take you to the next line (Assumption : The path variable is set).

·        Now, type ' java MyFirstJavaProgram ' to run your program.

·        You will be able to see ' Hello World ' printed on the window

Java - Environment Setup

 

 

Local Environment Setup

If you are still willing to set up your environment for Java programming language, then this section guides you on how to download and set up Java on your machine. Following are the steps to set up the environment.

Java SE is freely available from the link Download Java. You can download a version based on your operating system.

Follow the instructions to download Java and run the .exe to install Java on your machine. Once you installed Java on your machine, you will need to set environment variables to point to correct installation directories −

Setting Up the Path for Windows

Assuming you have installed Java in c:\Program Files\java\jdk directory −

·        Right-click on 'My Computer' and select 'Properties'.

·        Click the 'Environment variables' button under the 'Advanced' tab.

·        Now, alter the 'Path' variable so that it also contains the path to the Java executable. Example, if the path is currently set to 'C:\WINDOWS\SYSTEM32', then change your path to read 'C:\WINDOWS\SYSTEM32;c:\Program Files\java\jdk\bin'.

Setting Up the Path for Linux, UNIX, Solaris, FreeBSD

Environment variable PATH should be set to point to where the Java binaries have been installed. Refer to your shell documentation, if you have trouble doing this.

Example, if you use bash as your shell, then you would add the following line to the end of your '.bashrc: export PATH = /path/to/java:$PATH'

Popular Java Editors

To write your Java programs, you will need a text editor. There are even more sophisticated IDEs available in the market. But for now, you can consider one of the following −

·        Notepad − On Windows machine, you can use any simple text editor like Notepad (Recommended for this tutorial), TextPad.

·        Netbeans − A Java IDE that is open-source and free which can be downloaded from https://www.netbeans.org/index.html.

·        Eclipse − A Java IDE developed by the eclipse open-source community and can be downloaded from https://www.eclipse.org/

History of Java

                         History of Java

James Gosling initiated Java language project in June 1991 for use in one of his many set-top box projects. The language, initially called ‘Oak’ after an oak tree that stood outside Gosling's office, also went by the name ‘Green’ and ended up later being renamed as Java, from a list of random words.

Sun released the first public implementation as Java 1.0 in 1995. It promised Write Once, Run Anywhere (WORA), providing no-cost run-times on popular platforms.

On 13 November, 2006, Sun released much of Java as free and open source software under the terms of the GNU General Public License (GPL).

On 8 May, 2007, Sun finished the process, making all of Java's core code free and open-source, aside from a small portion of code to which Sun did not hold the copyright.

Tools You Will Need

For performing the examples discussed in this tutorial, you will need a Pentium 200-MHz computer with a minimum of 64 MB of RAM (128 MB of RAM recommended).

You will also need the following softwares −

• Linux 7.1 or Windows xp/7/8 operating system
• Java JDK 8
• Microsoft Notepad or any other text editor

This tutorial will provide the necessary skills to create GUI, networking, and web applications using Java.

Java - Overview

Java programming language was originally developed by Sun Microsystems which was initiated by James Gosling and released in 1995 as core component of Sun Microsystems' Java platform

The latest release of the Java Standard Edition is Java SE 8. With the advancement of Java and its widespread popularity, multiple configurations were built to suit various types of platforms. For example: J2EE for Enterprise Applications, J2ME for Mobile Applications.

The new J2 versions were renamed as Java SE, Java EE, and Java ME respectively. Java is guaranteed to be Write Once, Run Anywhere.

Java is −

·        Object Oriented − In Java, everything is an Object. Java can be easily extended since it is based on the Object model.

·        Platform Independent − Unlike many other programming languages including C and C++, when Java is compiled, it is not compiled into platform specific machine, rather into platform independent byte code. This byte code is distributed over the web and interpreted by the Virtual Machine (JVM) on whichever platform it is being run on.

·        Simple − Java is designed to be easy to learn. If you understand the basic concept of OOP Java, it would be easy to master.

·        Secure − With Java's secure feature it enables to develop virus-free, tamper-free systems. Authentication techniques are based on public-key encryption.

·        Architecture-neutral − Java compiler generates an architecture-neutral object file format, which makes the compiled code executable on many processors, with the presence of Java runtime system.

·        Portable − Being architecture-neutral and having no implementation dependent aspects of the specification makes Java portable. Compiler in Java is written in ANSI C with a clean portability boundary, which is a POSIX subset.

·        Robust − Java makes an effort to eliminate error prone situations by emphasizing mainly on compile time error checking and runtime checking.

·        Multithreaded − With Java's multithreaded feature it is possible to write programs that can perform many tasks simultaneously. This design feature allows the developers to construct interactive applications that can run smoothly.

·        Interpreted − Java byte code is translated on the fly to native machine instructions and is not stored anywhere. The development process is more rapid and analytical since the linking is an incremental and light-weight process.

·        High Performance − With the use of Just-In-Time compilers, Java enables high performance.

·        Distributed − Java is designed for the distributed environment of the internet.

·        Dynamic − Java is considered to be more dynamic than C or C++ since it is designed to adapt to an evolving environment. Java programs can carry extensive amount of run-time information that can be used to verify and resolve accesses to objects on run-time.