Computer Programming

Applying css styles in JavaFx dynamically

2015-12-14T22:44:00.002-08:00

We can apply the styles from a css file easily, which are fixed values defined in css, to any element in JavaFx directly by calling getStyleSheets() or getStyleClass().However, think of a scenario where the colours and styles are to be applied dynamically based on the unknown number of choices made available to the user. In this scenario, creating a separate style (or style class) per colour (or style) is practically not possible. However, here is an approach to apply dynamic styles.

With that being said, if you have any other method, I request you to share it and help others to learn more.

Source Code:



public class CssDemo extends Application {
	public static void main(String[] args) {
		launch(args);
	}

	@Override
	public void start(Stage primaryStage) {
		primaryStage.setTitle("Hello World!");
		final Button btn = new Button();
		btn.setText("Say 'Hello World'");
		btn.setOnAction(new EventHandler() {
			@Override
			public void handle(ActionEvent event) {
				try {
					String prefix = "background_";
					String suffix = ".css";

					// this temporary file remains after the jvm exits
					File tempFile = File.createTempFile(prefix, suffix);
					// to delete the files created in temp after the application closes
					// deletion happens only if the application exits properly
					tempFile.deleteOnExit();

					String cssContent = ".intro {   -fx-background-color: rgb("
							+ 67 + "," + 98 + "," + 288 + ")}";
					BufferedWriter bw = new BufferedWriter(new FileWriter(tempFile));
					bw.write(cssContent);
					bw.close();

					String filename = tempFile.getPath();
					btn.getStylesheets().add("file:///" + filename);
					btn.getStyleClass().add("intro");
				} catch (Exception e) {
					e.printStackTrace();
				}
			}
		});

		StackPane root = new StackPane();
		root.getChildren().add(btn);
		primaryStage.setScene(new Scene(root, 300, 250));
		primaryStage.show();
	}
}

Including a screenshot of the source code just to make sure it is clear to understand.

Happy Coding.

Palindrome Java Code made short

2015-10-04T23:50:00.000-07:00

I was asked by a friend to explain a palindrome program in java and I wanted to make it work for both integers and strings. In addition, wanted to make it short and understandable. Checking if a string is a palindrome or not is simple when compared to an integer palindrome. With a string, we can compare the first character with last character, second character with last but one character and so on. In java, we can convert an integer to string using Integer.toString().

In the below we have two methods, with the same name but different types of parameters passed. If an integer is passed parameter, it is converted to string and the same is passed to the method with string argument. Here it is checked if it is a palindrome by checking if it is like a mirror image, with mirror in the middle of the string. If yes, 1 is returned else, -1 is returned. The same value returned by string method is again returned by the integer method.

/**
* Created by Naveen Kumar on 9/30/2015.
*/
public class PalindromeDemo {
public static void main(String args[]){
   PalindromeDemo pd = new PalindromeDemo();
   System.out.println((pd.palindromeCheck(343)==1)?"Palindrome":"Not Palindrome");
   System.out.println((pd.palindromeCheck(3432)==1)?"Palindrome":"Not Palindrome");
   System.out.println((pd.palindromeCheck("madam")==1)?"Palindrome":"Not Palindrome");
   System.out.println((pd.palindromeCheck("abcd")==1)?"Palindrome":"Not Palindrome");
  }

    public int palindromeCheck(int n){
        return (new PalindromeDemo()).palindromeCheck(Integer.toString(n));
    }

    public int palindromeCheck(String str){
        for(int i=0;i<(str.length())/2;i++){
            if(str.charAt(i)!=str.charAt(str.length()-i-1))
                return -1;
        }
        return 1;
    }
}

Any comments or updates are welcome :)

Happy Coding.

UNIX Shell Scripting Leap Year

2014-02-22T10:33:00.000-08:00

I found the following algorithm on Leap Years.

In your favorite editor (like gedit), type in the following code.

Code: (leap_year.sh)
----------------------
echo "Enter a year : "
read y

if [ $(( $y % 4 )) -eq 0 -a $(( $y % 100 )) -ne 0 -o $(( $y % 400 )) -eq 0 ]
then
echo "$y is a leap year"
else
echo "$y is not a leap year"
fi

Execution:
----------
1. Open Terminal
2. Navigate to the directory containing the above script
3. bash leap_year.sh
or you can also do ./leap_year.sh provided you got execute permissions for the script.

Happy Coding.

JQuery, PHP, JSON

2014-02-22T04:02:00.000-08:00

This post is mostly the same as the previous one which is about JQuery, PHP and JSON. But the difference is, in the previous post, only rendering is done not validation of answers. Now, I have included the validation part also. Once the user is done answering and clicks submit button, answers are checked with correct answers and final result is displayed as an alert. Same as previous post, the PHP file, which is supposed to get data from database and convert it into json format and echo the result, just echos a string which is a collection of questions in json format.

index.html
----------
<html>
<head>
<script src="jquery-1.10.2.js"></script>
<script src="jquery_functions4.js"></script>
</head>
<body>
<p> Its working fine </p>
<table align='center' border='1' id='results'> </table>
<div id='test'> </div>
</body>
</html>

get_qp.php
------------
<?php
echo ' {"question_paper":
[
{
"qid": "1",
"question": "Who is the father of computer?",
"opt1": "Charless Babbage",
"opt2": "Spider Man",
"opt3": "Professor X",
"opt4": "Robin Hood",
"answer": "a"
},
{
"qid": "2",
"question": "Who is the father of Java?",
"opt1": "Charless Babbage",
"opt2": "James Gauslin",
"opt3": "Professor X",
"opt4": "Robin Hood",
"answer": "b"
},
{
"qid": "3",
"question": "Who designed C Language?",
"opt1": "Charless Babbage",
"opt2": "Spider Man",
"opt3": "Dennis Ritchie",
"opt4": "Robin Hood",
"answer": "c"
}
]
}';

?>

jquery_functions4.js
--------------------
$(document).ready(function()
{
var answers = new Array();
var qids = new Array();
var user_response = new Array();
var i = 0;
var res = 0;
var div_data="";

$.getJSON("get_qp.php",function(data)
{
$.each(data.question_paper,function(i,qp)
{
div_data+="<tr>"
div_data+="<td>"+qp.qid+"</td>";
div_data+="<td colspan='4'>"+qp.question+"</td>";
div_data+="</tr>";
div_data+="<tr>";
div_data+="<td></td>";
div_data+="<td><input type='radio' id='"+qp.qid+"' name = "+qp.qid+" value='a'/>"+qp.opt1+"</td>";
div_data+="<td><input type='radio' id='"+qp.qid+"' name = "+qp.qid+" value='b'/>"+qp.opt2+"</td>";
div_data+="<td><input type='radio' id='"+qp.qid+"' name = "+qp.qid+" value='c'/>"+qp.opt3+"</td>";
div_data+="<td><input type='radio' id='"+qp.qid+"' name = "+qp.qid+" value='d'/>"+qp.opt4+"</td>";
div_data+="</tr>";

qids[i] = qp.qid;
answers[i++] = qp.answer;
});

div_data+="<tr><td colspan='5' align='center'><input type='submit' value='SUBMIT' id='submit_button'/></td></tr>";
$("#results").html(div_data);

$("#submit_button").click(function()
{
$("#results").hide();
res = 0;
for(var i=0;i<3;i++)
{
user_response[i] = $("input:radio[name="+qids[i]+"]:checked").val();
if(user_response[i] == answers[i])
res++;
}
alert("Your Score:"+res);
});
});
});

jquery-1.10.2.js can be downloaded online. It is JQuery API.
All the files are present in the same folder which is under c:\wamp\www\. For example, my project name is json_testing so I have saved these files under c:\wamp\www\json_testing\

Hope this helps. Happy Coding.

JQuery PHP & JSON

2014-02-08T09:00:00.000-08:00

First, the JQuery function requests the PHP file for the data to be sent.
The server side code in PHP, requests the database for the data and gets the data.
Converts the received data into JSON format and sends it to the client side.
On the client side, JQuery (java script) receives the data in JSON format, extracts the required information, processes accordingly and displays in a table format.

Here in this example, the database connectivity is not included, rather, a JSON format is generated which is a question paper (objective type).

Client Side code: (index.html)
------------------
<html>
<head>
<script src="jquery/jquery-1.10.2.js"></script>
<script src="jquery_functions3.js"></script>
</head>
<body>
<p> Its working fine </p>
<table border='1' id="results"> </table>
</body>
</html>

Server Side code: (get_qp.php)
------------------
<?php
echo ' {"question_paper":
[
{
"qid": "1",
"question": "Who is the father of computer?",
"opt1": "Charless Babbage",
"opt2": "Spider Man",
"opt3": "Professor X",
"opt4": "Robin Hood",
"answer": "a"
},
{
"qid": "2",
"question": "Who is the father of Java?",
"opt1": "Charless Babbage",
"opt2": "James Gauslin",
"opt3": "Professor X",
"opt4": "Robin Hood",
"answer": "b"
},
{
"qid": "3",
"question": "Who designed C Language?",
"opt1": "Charless Babbage",
"opt2": "Spider Man",
"opt3": "Dennis Ritchie",
"opt4": "Robin Hood",
"answer": "c"
}
]
}
';

?>

JavaScript code (JQuery): (jquery_functions3.js)
--------------------------
$(document).ready(function()
{
$.getJSON("get_qp.php",function(data)
{
$.each(data.question_paper,function(i,qp)
{
var div_data = "<tr><td>"
+qp.qid+"</td><td colspan=4>"+qp.question+"</td></tr><tr><td></td><td><input type='radio' name='"+qp.qid+"'>"+qp.opt1+"</td><td><input type='radio' name='"+qp.qid+"'>"+qp.opt2+"</td><td><input type='radio' name='"+qp.qid+"'>"+qp.opt3+"</td><td><input type='radio' name='"+qp.qid+"'>"+qp.opt4+"</td></tr>";

$("#results").append(div_data);
});
});
});

Points to remember before proceeding with execution:
-----------------------------------------------------
1. I used WAMP for the above code.
2. JQuery API should be downloaded and included if you dont want to use an online API.
3. Make sure that you are running an updated version on Java.
4. All the above three files are to be present in the same folder. If you want to keep the js file separately, then make sure that you do required modification in the html file.

Happy Coding.

Output:

Distributed Computing, Connection Oriented Socket API

2013-11-05T09:31:00.003-08:00

In my previous posts, I shared about connection less communication with socket API. This post is about connection oriented communication with socket API.
In the case of connection less communication, the packets are received at the receiver at random. Which means, if you consider packets received consecutively, the collection may contain packets in a random order and may be from many senders.
Connection oriented communication is also called Stream-mode communication where the packets are written to the stream by a sender and the receiver reads these packets from the stream.
In java, to implement Connection Oriented socket communication, two classes are used
1. ServerSocket (to establish and maintain the connection)
2. Socket (for data exchange)

Demo1:
The following program demonstrates a basic Connection Oriented communication between two processes, ConnectionAcceptor and ConnectionRequestor, running on two different hosts. ConnectionAcceptor process accepts a connection from ConnectionRequestor process and sends back a response provided in the command line arguments. ConnectionRequestor process sends a connection request to the ConnectionRequestor process, gets a response and prints the received response.

Code (ConnectionAcceptor):
import java.net.*;
import java.io.*;

/*
* ****** CONNECTION ORIENTED SOCKET PROGRAMMING *****
*   Author : @NaveenKumar
* Program : Connection Acceptor (Server)
*   Date : 29/10/2013
*   File Name    : ConnectionAcceptor.java
*/

public class ConnectionAcceptor
{
public static void main(String args[])
{
if(args.length != 2)
{
  System.out.println("Error in required no. of parameters");
}// end of if
else
{
try{
int portNo = Integer.parseInt(args[0]);
String message = args[1];
ServerSocket connectionSocket = new
ServerSocket(portNo);
System.out.println("Waiting for connection");
Socket dataSocket = connectionSocket.accept();
System.out.println("Connection Accepted");
OutputStream outStream =
dataSocket.getOutputStream();
PrintWriter socketOutput = new PrintWriter(new    OutputStreamWriter(outStream));
socketOutput.println(message);
socketOutput.flush();
System.out.println("Message sent");
try{
  Thread.sleep(5000);
  System.out.println("Waiting time is over");
}catch(Exception e)
{
e.printStackTrace();
}
socketOutput.println(message);
socketOutput.flush();
dataSocket.close();
System.out.println("Data socket closed");
connectionSocket.close();
System.out.println("connection socket closed");
}catch(Exception ex){
ex.printStackTrace();
}//end of catch
}//end of else
}// end of main
}// end of class ConnectionAcceptor

Code (Connection Requestor):
import java.net.*;
import java.io.*;

/*
* ****** CONNECTION ORIENTED SOCKET PROGRAMMING *****
*   Author : @NaveenKumar
* Program : Connection Requestor (client)
*   Date : 29/10/2013
*   File Name   : ConnectionRequestor.java
*/

public class ConnectionRequestor
{
public static void main(String args[])
{
if(args.length != 2)
{
System.out.println("Insufficient parameters");
}// end of if
else
{
try{
InetAddress acceptorHost =InetAddress.getByName(args[0]);
int acceptorPort = Integer.parseInt(args[1]);
Socket mySocket = new Socket(acceptorHost, acceptorPort);
System.out.println("Connection request granted");
InputStream inStream = mySocket.getInputStream();
BufferedReader socketInput = new BufferedReader(new
InputStreamReader(inStream));
System.out.println("waiting to read");
String message = socketInput.readLine();
System.out.println("Message received:\t"+message);
mySocket.close();
System.out.println("Data Socket closed");
}catch(Exception ex){
ex.printStackTrace();
}//end of catch
}// end of else
}// end of main
} // end of ConnectionRequestor

Executing Procedure:
1. Deploy the above programs in two different nodes which are connected on a network
2. Open terminal (command prompt) on both the nodes
3. navigate to the above java file locations
4. On terminal 1, javac ConnectionAcceptor.java (press enter),
java ConnectionAcceptor 3000 hai (press enter)
5. On the other terminal, javac ConnectionRequestor.java (press enter)
java ConnectionRequestor 192.168.10.1 3000 (press enter)
192.168.10.1 is the IP address of the node that is running the ConnectionAcceptor process and 3000 is the port number on which it is listening.

'hai' is the response send back to the ConnectionRequestor process by ConnectorAcceptor process.

Demo 2:
Now, a modified version of the above ConnectionAcceptor is as follows. The modification provided is that, instead of accepting one single connection, it can accept multiple connections. The ConnectionAcceptor process is not terminated.

for better understanding, the new ConnectionAcceptor is renamed as Server.

Code (Server):
import java.net.*;
import java.io.*;

/*
* ****** CONNECTION ORIENTED SOCKET PROGRAMMING *****
* Author : @NaveenKumar
* Program : Server
* Date : 29/10/2013
* File Name   : Server.java
*/

public class Server
{
public static void main(String args[])
{
if(args.length != 2)
{
System.out.println("Error in required no. of parameters");
}// end of if
else
  {
try{
int portNo = Integer.parseInt(args[0]);
String message = args[1];

ServerSocket connectionSocket = new ServerSocket(portNo);
System.out.println("Waiting for connection");
int i,j;
i = j = 1;
while(i==j)
{
  Socket dataSocket = connectionSocket.accept();
  System.out.println("Connection Accepted");
  OutputStream outStream = dataSocket.getOutputStream();
  PrintWriter socketOutput = new PrintWriter(new
OutputStreamWriter(outStream));
  socketOutput.println(message);
  socketOutput.flush();
  System.out.println("Message sent");
  try{
Thread.sleep(5000);
System.out.println("Waiting time is over");
  }catch(Exception e)
  {
e.printStackTrace();
  }
  socketOutput.println(message);
  socketOutput.flush();

  dataSocket.close();
  System.out.println("Data socket closed");
}
connectionSocket.close();
System.out.println("connection socket closed");
}catch(Exception ex){
ex.printStackTrace();
}//end of catch
}//end of else
}// end of main
}// end of class Server

Code (Client):
import java.net.*;
import java.io.*;

/*
* ****** CONNECTION ORIENTED SOCKET PROGRAMMING *****
* Author : @NaveenKumar
* Program : Client
* Date : 29/10/2013
* File Name   : Client.java
*/

public class Client
{
public static void main(String args[])
  {
if(args.length != 2)
{
System.out.println("Insufficient parameters");
}// end of if
else
{
try{
InetAddress acceptorHost = InetAddress.getByName(args[0]);
int acceptorPort = Integer.parseInt(args[1]);
Socket mySocket = new Socket(acceptorHost, acceptorPort);
System.out.println("Connection request granted");
InputStream inStream = mySocket.getInputStream();
BufferedReader socketInput = new BufferedReader(new
InputStreamReader(inStream));
System.out.println("waiting to read");
String message = socketInput.readLine();
System.out.println("Message received:\t"+message);
mySocket.close();
System.out.println("Data Socket closed");
}catch(Exception ex){
ex.printStackTrace();
}//end of catch
}// end of else
}// end of main
} // end of Client

Execution:
One Server process running on a host on a network, multiple Client processes running on multiple hosts on the network.
1. Deploy the above programs in different hosts which are connected on a network
2. Open terminal (command prompt) on both the nodes
3. navigate to the above java file locations
4. On terminal 1, javac Server.java (press enter),
java Server 3000 hai (press enter)
5. On the other terminals, javac Client.java (press enter)
java Client 192.168.10.1 3000 (press enter)
192.168.10.1 and 3000 are the IP address and port number of the Server Process.

Try executing multiple clients simultaneously and observe the happenings.
If you dont have multiple hosts available, then for demonstration purpose, you can do execution on localhost itself as demonstrated in the class.

Distributed Computing, Socket API Prime Number identification from a list of numbers

2013-10-30T01:42:00.001-07:00

In the previous example, we looked into a connection less java Socket API Program. Now, assume that there are 4 nodes in the distributed system and 100 numbers given as input are to be processed (for example, checking if a given number is a prime or not). Now we need a master node to accept this input and proceed with assigning of the work and again displaying the final output. For simplicity, I am giving input as the first 100 natural numbers.

The Setup is assumed to consist of one 5 nodes. One master and others as slaves.

Code: Master.java

import java.net.*;

import java.io.*;

* ************* SOCKET PROGRAMMING (Master) **************

*Author : @NaveenKumar

*Program :To print prime numbers in [1,100]

*Date : 29/10/2013

*File Name : Master.java

public class Master

{

public static void main(String args[])

{

int num;

try{

InetAddress[] receiverHost = {

InetAddress.getByName("127.0.0.1"),

InetAddress.getByName("127.0.0.1")};

int[] receiverPort = {3000,3010,3020,3030};

String message;

//instantiate a datagram socket for sending the data

DatagramSocket s = new DatagramSocket();

DatagramSocket s1 = new DatagramSocket(3500);

byte[] buffer;

for(int i=1;i<=100;i++)

{

message = Integer.toString(i);

buffer = message.getBytes();

DatagramPacket p = new

DatagramPacket(buffer,buffer.length,

receiverHost[i%4],receiverPort[i%4]);

s.send(p);

}

s.close();

byte[] buffer1;

String msg1;

for(int i = 0;i<100 i="" o:p="">

{

buffer1 = new byte[10];

DatagramPacket p1 = new DatagramPacket

(buffer1,10);

s1.receive(p1);

msg1 = new String(buffer1);

//num = Integer.parseInt(msg1);

if(msg1.charAt(0)!='-')

System.out.println("Received: "+msg1);

}

s1.close();

}catch(Exception ex)

{

ex.printStackTrace();

}//end of catch

}//end of main

}//end of class

In the above program for Master node, a list of nodes in the network are provided with the port numbers of respective node on which they are listening. Once the processing of data is done on the other nodes, then the results are then processed on the Master node and displayed. If the number -1 is received from any slave, it is ignored but if a positive integer is received, then it is printed.

Code: Slave.java

import java.net.*;

import java.io.*;

* ******************** SOCKET PROGRAMMING (SLAVE) **************

* Author : @NaveenKumar

* Date : 29/10/2013

* File Name : Receiver.java

public class Slave

{

public static void main(String args[])

{

System.out.println("Starting Receiver");

if(args.length!=1)

{

System.out.println("Invalid no. of args");

}

else{

int receive_port = Integer.parseInt(args[0]);

try

{

DatagramSocket s = new

DatagramSocket(receive_port);

DatagramSocket soc = new DatagramSocket();

System.out.println("Socket created");

byte[] buffer = new byte[10];

System.out.println("buffer created");

DatagramPacket p = new DatagramPacket(buffer,10);

System.out.println("packet created");

int i,j;

i=10;

j=10;

String msg;

Slave sl = new Slave();

while(i==j)

{

s.receive(p);

msg = new String(buffer);

// process the message

sl.process(msg,soc);

}

s.close();

}catch(Exception ex) // end of try and start of catch

{

ex.printStackTrace();

}// end of catch

}//end of else

}// end of main

public Slave()

{

}

public void process(String msg, DatagramSocket s1)

{

String msg1="";

String msg2 = "";

String message = msg;

int res = -1;

byte[] buffer;

for(int k=0;k

{

if((int)message.charAt(k)<58 amp="" nbsp="" span="">

(int)message.charAt(k)>47)

msg2 += message.charAt(k);

else

break;

}

int num = Integer.parseInt(msg2);

int temp = 0;

for(int i=1;i

{

if(num%i == 0)

temp++;

if(temp==2)

break;

}

if(temp==1)

res = num;

else

res = -1;

try{

InetAddress receiverHost =

InetAddress.getByName("127.0.0.1");

int receiverPort = 3500;

msg1 = Integer.toString(res);

System.out.println("Msg: "+msg1);

buffer = msg1.getBytes();

DatagramPacket p1 = new DatagramPacket(buffer,

buffer.length,receiverHost,receiverPort);

s1.send(p1);

}catch(Exception ex)

{

ex.printStackTrace();

}// end of catch

}//end of process method

}// end of class Receiver

In the above code for Slave process, slave process waits for receiving a message from Master process. Once a number is received, it calls process() method with the received message as a parameter to this method. Here in this method, the received data is converted into integer and then checked if it is a prime number of not. If it is a prime number, the number itself is sent back to the Master. If it is not a prime number, then -1 is sent back.

Distributed Computing, Socket API

2013-10-29T04:15:00.000-07:00

This post is to help my students, in IV year B.Tech (IT), understand a programming facility for IPC, that is, socket API in Distributed Computing. Socket API provides a low level of abstraction for IPC. This API is appropriate if the resources are limited in a Distributed Environment.

In this post I am going to implement a basic Java Socket program first and then I consider a problem that is solved in a distributed environment with IPC programmed with sockets in java.

In the first application, the job here is to send a message to a receiver node from a sender node where, the message is displayed at the receiver to show that the received message is processed.

The Socket programming implementation of IPC is Asynchronous send and Synchronous receive, because the sender doesn't enter blocking state while sending the message but the receiver will enter into blocking state till the message is received.

The scenario here is, a process Sender is running on a Host A and the other process Receiver is running on Host B.

Code : Sender
---- - ------
import java.net.*;
import java.io.*;
/*
* *************** SOCKET PROGRAMMING (SENDER) **************
* Author : @NaveenKumar
* Date : 29/10/2013
* File Name : Sender.java
*/
public class Sender
{
public static void main(String args[])
{
  if(args.length!=3)
  {
   System.out.println("Insufficient parameters");
}// end of if
  else
  {
  System.out.println("Parameters read");
try{
InetAddress receiverHost=InetAddress.getByName(args[0]);
int receiverPort = Integer.parseInt(args[1]);
String message = args[2];
System.out.println("Arguments copied into variables");
//instantiate a datagram socket for sending the data
DatagramSocket s = new DatagramSocket();
System.out.println("Datagram Socket instantiated");
byte[] buffer = message.getBytes();
DatagramPacket p = new
DatagramPacket(buffer,buffer.length,
receiverHost,receiverPort); System.out.println("Datagram Packet instantiated"); s.send(p);
s.close();
}catch(Exception ex) //end of try and beginning of catch
{
ex.printStackTrace();
}//end of catch
}// end of else
}//end of main
}//end of class

In the above program, the Receiver IP address, Receiver Port number and message to be sent are taken as arguments to main function. Required parameters like Receiver's IP address, Port number, message are set before instantiating the Datagram socket.

After the socket is instantiated (in this case the socket is 's'), a Datagram Packet is instantiated (in this case it is 'p') with the IP address of its receiver, port number and message are bundled into the packet.

Now, the packet is sent through the socket 's', to the receiver socket.

Code : Receiver
---- - --------
import java.net.*;
import java.io.*;

/*
* **************** SOCKET PROGRAMMING (RECEIVER) **************
* Author : @NaveenKumar
* Date : 29/10/2013
* File Name : Receiver.java
*/

public class Receiver
{
public static void main(String args[])
{
System.out.println("Starting Receiver");
if(args.length!=1)
{
System.out.println("Insufficient arguments");
}// end of it
else
{
System.out.println("Success on number of arguments");
int receive_port = Integer.parseInt(args[0]);
try
{
DatagramSocket s = new DatagramSocket(receive_port);
System.out.println("Socket created");
byte[] buffer = new byte[10];
System.out.println("buffer created");
DatagramPacket p = new DatagramPacket(buffer,10);
System.out.println("packet created");
s.receive(p);
System.out.println("Received message successfully");
String msg = new String (buffer);
System.out.println(msg);
s.close();
}catch(Exception ex) // end of try and start of catch
{
ex.printStackTrace();
}// end of catch
}// end of else
}// end of main
}// end of class Receiver

In this case of the Receiver process running on Host B, a Datagram Socket is instantiated to facilitate the receive operation, a Datagram Packet is instatitated and when the receive operation is reached, the process is sent to blocked state and set to wait for the message to be received from the Sender.

To show the blocking, checksums are provided at each stage. Once the receive operation is completed, the process is unblocked and continued with the processing of data.

The communication in the above scenario is between two processes Sender and Receiver performing either send or receive operations respectively but any process can send as well as receive data to/from other processes running on same or different hosts. That may be illustrated in the next post.

Hope this is helpful.

Fee Payment Module

2013-06-01T09:40:00.004-07:00

Hi
After the last hello world program in javafx, I started developing an app to check for student fee payment details based on the bill number. Only the interface part is done.

In developing this interface, I have used BorderPane, StackPane, HBox, VBox, TextField, Label, and Button (to toggle fullscreen mode).

The interface displays the college name, department (in this case it is Academic Section), followed by date. There is a text field that takes the bill number.
A Full screen button to toggle fullscreen.

Hope it is useful for your understanding of javafx.

Source Code:
/**
* Created with IntelliJ IDEA.
* User: NaveenKumar
* Date: 1/6/13
* Time: 10:16 AM
*/

package FeeReceipt;

import javafx.application.Application;
import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.geometry.Insets;
import javafx.geometry.Pos;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.Label;
import javafx.scene.control.TextField;
import javafx.scene.image.Image;
import javafx.scene.image.ImageView;
import javafx.scene.layout.*;
import javafx.scene.paint.Color;
import javafx.scene.paint.CycleMethod;
import javafx.scene.paint.LinearGradient;
import javafx.scene.paint.Stop;
import javafx.scene.shape.Rectangle;
import javafx.scene.text.Font;
import javafx.scene.text.FontWeight;
import javafx.scene.text.Text;
import javafx.stage.Stage;

import java.util.Date;
import java.util.GregorianCalendar;

public class Main extends Application {

public static void main(String[] args){
launch(args);
}

@Override
public void start(final Stage stage) throws Exception {
stage.setFullScreen(true);

BorderPane border = new BorderPane();
VBox vbox_top = new VBox();
vbox_top.setAlignment(Pos.CENTER);
vbox_top.setPadding(new Insets(10,10,10,10));
vbox_top.setStyle("-fx-background-color: #A9D0F5");

// College Name
Label colg_name = new Label();
colg_name.setText("XYZ College of Engineering");
colg_name.setFont(Font.font("Calibri", FontWeight.BOLD, 35));

// Academic Section
Label academic_section = new Label();
academic_section.setText("Academic Section");
academic_section.setFont(Font.font("Arial", FontWeight.BOLD, 30));

//Fee Receipt
Label fee_receipt = new Label();
fee_receipt.setText("(Fee Receipt)");
border.setTop(vbox_top);
fee_receipt.setFont(Font.font("Verdana", FontWeight.BOLD, 20));

HBox hbox1 = new HBox();
//Bill No
Label bill_no = new Label();
bill_no.setText("Bill No:");
bill_no.setFont(Font.font("Verdana", FontWeight.NORMAL, 18));

//Bill Number Text field
TextField bno = new TextField();
bno.setPrefColumnCount(8);

hbox1.getChildren().addAll(bill_no,bno);

//date
Label dt = new Label();
dt.setText("Date:");

StackPane dt_stack = new StackPane();
Rectangle dt_rect = new Rectangle(150.0,25.0);
dt_rect.setFill(new LinearGradient(0,0,0,1,true, CycleMethod.NO_CYCLE,
new Stop[]{
new Stop(0, Color.web("#4977A3")),
new Stop(0.5,Color.web("#B0C6DA")),
new Stop(1,Color.web("9CB6CF")),
}));
dt_rect.setStroke(Color.web("#D0E6FA"));
dt_rect.setArcHeight(3.5);
dt_rect.setArcWidth(3.5);

Date dt_today = new Date();
String dt_today1 = dt_today.toString().substring(4,10)+" "+dt_today.toString().substring(dt_today.toString().length()-4,dt_today.toString().length());
Text dt_text = new Text(" "+dt_today1);
dt_text.setFont(Font.font("verdana", FontWeight.BOLD, 18));
dt_text.setFill(Color.WHITE);
dt_text.setStroke(Color.web("#7080A0"));
dt_stack.getChildren().addAll(dt_rect,dt_text);
dt_stack.setAlignment(Pos.CENTER_LEFT);

//stack pane for full screen button
StackPane stack = new StackPane();

ImageView fs = new ImageView(
new Image(Main.class.getResourceAsStream("graphics/view-fullscreen.png")));
Button fullScrn = new Button();
fs.setFitHeight(30);
fs.setFitWidth(30);
fs.setPreserveRatio(true);

fullScrn.setGraphic(fs);

//full screen event handler
fullScrn.setOnAction(new EventHandler() {
@Override
public void handle(ActionEvent e) {
stage.setFullScreen(!stage.isFullScreen());
}
});

stack.getChildren().addAll(fullScrn);
stack.setAlignment(Pos.CENTER_RIGHT);
StackPane.setMargin(fullScrn,new Insets(0,10,0,0));
// end of stack pane

hbox1.getChildren().addAll(stack);
HBox.setHgrow(stack, Priority.ALWAYS);

vbox_top.getChildren().addAll(colg_name, academic_section, fee_receipt,dt_stack,hbox1);

Scene scene = new Scene(border);
stage.setScene(scene);
stage.setTitle("Fee Payment");
stage.show();
}
}

OUTPUT:

Feel free to leave a comment. Thanks for visiting. Have a nice day.

JavaFX Hello World

2013-05-30T07:39:00.000-07:00

This is my first JavaFX application. It is kinda similar to the first Hello World application in the tutorials but I made a few modifications (not bigger modifications but a considerable ones).
Hope you guys enjoy coding in fx.

SOURCE CODE (HELLO WORLD)
package sample;

import javafx.application.Application;
import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.geometry.Insets;
import javafx.geometry.Pos;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.layout.GridPane;
import javafx.stage.Stage;

public class Main extends Application{
public static void main(String[] args)
{
System.out.println("Launching Hello World Application");
launch(args);
}
@Override
public void start(final Stage primaryStage) {
System.out.println("Preparing the stage");
primaryStage.setTitle("Hello World");
System.out.println("Title set to Hello World");
System.out.println("Creating a new button and setting button text to Say 'Hello World'");
Button btn = new Button();
btn.setText("Say 'Hello World'");
System.out.println("Creating event handler for Hello World Button");
btn.setOnAction(new EventHandler() {

@Override
public void handle(ActionEvent event) {
System.out.println("Hello World");
}

});
System.out.println("Creating another Button to exit");
Button btn_exit = new Button();
btn_exit.setText("Exit");
System.out.println("Creating event handler for exit button");
btn_exit.setOnAction(new EventHandler() {
@Override
public void handle(ActionEvent actionEvent) {
System.out.println("Closing the applicaion");
primaryStage.close();
}
});

GridPane grid = new GridPane();
grid.setAlignment(Pos.CENTER);
grid.setHgap(10);
grid.setVgap(10);
grid.setPadding(new Insets(25,25,25,25));
Scene scene = new Scene(grid,300,275);

grid.add(btn,0,1);
grid.add(btn_exit,1,1);

primaryStage.setScene(scene);
primaryStage.show();
}

}

OUTPUT SNAPSHOTS:

Keep visiting for more posts.

Introduction to Java

2012-07-19T18:41:00.000-07:00

Java is an Object Oriented Programming language. Java is developed by James Gosling from Sun Microsystems in the year 1991. Java is a platform independent language which means, a java program compiled on a machine can be run on any machine with a JVM installed on it.

Java programming language consists of Java compiler, Java Virtual Machine (JVM) and the java programming libraries. The java compiler converts the java code into byte code, which is understood by JVM and is interpreted into machine dependent code for execution on the machine which runs JVM. JVM is machine dependent. Each operating system got its own JVM.

Requirements to write and run a java program.
1. Java Runtime Environment (JRE)
2. Java Development Kit (JDK)
3. Editor (notepad, wordpad, notepad++, edit plus, etc) or an IDE like Eclipse or Netbeans can also be used.

Using an IDE saves time in many ways.
As of now, I am using Netbeans IDE for executing all the examples in this post.
Netbeans looks as follows:

Java Basic Syntax:
Class: In an Object Oriented Programming, a class is a construct that is used to create instances of itself. It can also be defined as a template/blue print that describes the behaviors/states that object of its type support.
Object: An object is a location in memory having a value and referenced by an identifier. Objects have states and behaviors.
Methods: A method is a behavior. (In C language it is like a function). A class can contain many methods. It is in methods where the logic are written, data is manipulated and all the actions are executed.
Instant Variables: Each object has its unique set of instant variables. An object's state is created by the values assigned to these instant variables.

First program:
Learning any programming language starts with Hello World program. So, java hello world program is coded as below

public class HelloWorld
{
public static void main(String args[])
{
System.out.println("Hello World");
}
}

if you are using a notepad or any other editor for writing your java programs, you should compile and execute your java program form terminal or command prompt. Following are the steps to do that
1. Open command prompt
2. move to the location where your java file is located
3. if your java file is named HelloWorld.java (as it is compulsory for the public class name to match with the file name), then give "javac HelloWorld.java" with out the quotes. This gives HelloWorld.class file. If you get an error in doing this most probably class path is not set. Please take care of that. HelloWorld.class contains the byte code for the java code in HelloWorld.java.
4. Executing java code needs the .class file. It is done by entering in command prompt the following
"java HelloWorld" without the quotes.

if you are using an IDE, then it is very simple. Just right click on the file you want to execute and select run file form the right click menu. You can see the output in the output panel below your code area.

Points to remember while writing a java program
1. Java is a case sensitive programming language. Example, the identifiers 'A' and 'a' are considered as different.
2. Class names should start with upper case. If a class name has more than one word, then first letter of each word should be in upper case. Ex: HelloWorld
3. All method names should start with a lower case letter and if there are more words in a method name, then except for first word, other words should start with upper case. helloWorld()
4. Name of the program file should be same as the public class name in the java program. HelloWorld.java is file name for the program with public class HelloWorld.
5. a java program processing starts from the main() method. It is compulsory for any java program. Its syntax is public static void main(String args[]). main() method takes string arguments.

Java Keywords:
abstract, assert, boolean, break, byte, case, catch, char, class, const, continue, default, do, double, else, enum, extends, final, finally, float, for, goto, if, implements, import, instanceof, int, interface, long, native, new, package, private, protected, public, return, short, static, strictfp, super, switch, synchronized, this, throw, throws, transient, try, void, volatile, while.

Note: Single line comments and double line comments are same as in C and C++ programming.

Data types:
byte, short, int, long, float, double, boolean ,char.

Escape sequences for string and char literals:
\n -----> New line (0x0a)
\r -----> Carriage return (0x0d)
\f -----> Formfeed (0x0c)
\b -----> Backspace (0x08)
\s -----> Space (0x20)
\t -----> Tab
\" -----> Double quote
\' -----> Single quote
\\ -----> backslash
\ddd ---> Octal Character (ddd)
\uxxxx -> Hexadecimal UNICODE character (xxxx)

Operators
1. Arithmetic Operators:

+ Addition
- Subtraction
* Multiplication
/ Division
% Modulus
++ Increment
-- Decrement

2. Relational Operators:

== if equals, returns true
!= if not equals, returns true
> if greater than, returns true
< if less than, returns true
>= greater than or equal to
<= less than or equal to

3. Bitwise Operators:

& Binary AND
| Binary OR
^ Binary XOR
~ Binary ones complement
<< Binary Left Shift Operator
>> Binary Right Shift Operator
>>> Shift right zero full operator

4. Logical Operators:

&& Logical AND operator. If both the operands are non zero, then conditions becomes true
|| Logical OR operator. If any of the two operands are non zero, then condition becomes true
! Logical NOT operator. Used to reverse the state of its operand.

5. Assignment Operators:

= Simple assignment operator
+= Add and assignment operator
-= Subtract and assignment operator
*= Multiply and assignment operator
/= Divide and assignment operator
%= Modulus and assignment operator

6. Conditional Operator

( ? : ) :
variable x = (expression) ? value if true : value if false
Example: a = (10>20)?10:20

Decision Making in Java:
Different decision making statements include if, if-else,else if ladder, switch, for, while, do-while .
Following gives syntax for each of these decision making statements with an example for each.

a. if statement:
Syntax:
if(test_condition)
{
// true block
}

Example:

public class if_statement {
public static void main (String args[])
{
int a = 10, b = 20;
if(a
{
System.out.println("b is bigger than a");
}
if(a>b)
{
System.out.println("a is bigger than b");
}
}
}

b. if-else statement

Syntax:

if(test_condition)

{

//true block

}

else

{

//false block

}

Example:

public class if_else_statement {
public static void main (String args[])
{
int a = 10, b = 20;
if(a &lt b)
{
System.out.println("b is bigger than a");
}
else
{
System.out.println("a is bigger than b");
}
}
}

c. else-if ladder:
Syntax:
if(test_condition1)
{
// true block1
}
else if(test_condition2)
{
//true block 2
}
.
.
.
else if(test_condition n)
{
// true block n
}
else
{
// false block
}

Example:

public class if_else_ladder_statement {
public static void main (String args[])
{
int a = 10, b = 20, c = 30;
if(a &gt b && a &gt c)
{
System.out.println("a is biggest");
}
else if(b &gt a && b &gt c)
{
System.out.println("b is biggest");
}
else
{
System.out.println("c is biggest");
}
}
}

d. switch:
Syntax:
switch(condition)
{
case 1: // statements;
break;

case 2: // statements;
break;

case 3: // statements;
break;
...
...

case n: // statements;
break;
default: // statements;
}

Example:

public class switch_statement {
public static void main (String args[])
{
int a = 2;
switch(a)
{
case 1: System.out.println("case 1");
break;
case 2: System.out.println("case 2");
break;
case 3: System.out.println("case 3");
break;
default: System.out.println("no cases matched. default cse");
}
}
}

e. for loop:
Syntax:
for(initialization; test_condition; increment)
{
// loop body
}

Example:

public class for_loop{
public static void main (String args[])
{
for(int i=0;i &lt 10;i++)
{
System.out.println(i);
}
}
}

f. while loop
Syntax:
while(test_condition)
{
// loop body
}

Example:

public class while_loop {
public static void main (String args[])
{
int i=0;
while(i &lt 10)
{
System.out.println(i);
i++;
}
}
}

g. do-while loop:
Syntax:
do
{
// loop body
}while(test_condition);

Example:

public class if_statement {
public static void main (String args[])
{
int i=0;
do
{
System.out.println(i);
i++;
}while(i &lt 10);
}
}

This post briefs a very few things in java. Hope this helps. Keep visiting my blog for more topics. Thank you.

Binary Search Tree without recursion in java

2012-06-12T14:00:00.000-07:00

/**
*
* @author Naveen Kumar
*/
public class BST {
static node1 n, root;
public static void main(String args[])
{
if(n==null)
System.out.println("node is null");
int[] elements = {1,1,2,3,2,2,5,4,4,6,5,6,7,8,7,9};

for(int i=0;i<elements.length;i++)
{
insert(elements[i], root);
display(root);
System.out.println();
}
}

static void insert(int a, node1 n)
{
if(root == null)
{
root = new node1();
root.data = a;
root.count++;
root.left = null;
root.right = null;
}
else
{
node1 m = new node1();
m = root;
while(m!=null)
{
if(m.data>a)
{
if(m.left==null)
{
node1 temp = new node1();
temp.data = a;
temp.count++;
temp.left = null;
temp.right = null;
m.left = temp;
return;
}
else
{
m = m.left;
}
}
else if(m.data<a)
{
if(m.right==null)
{
node1 temp = new node1();
temp.data = a;
temp.count++;
temp.left = null;
temp.right = null;
m.right = temp;
return;
}
else
{
m = m.right;
}
}
else
{
m.count++;
return;
}
}
}
}

static void display(node1 n)
{
if(n==null)
return;
display(n.left);
System.out.print(n.data+"\t");
display(n.right);
}
}

class node1
{
int data;
int count;
node1 left;
node1 right;

public node1()
{
this.left = null;
this.right = null;
this.data = 0;
this.count = 0;
}
}

Binary Search Tree implementation using Linked Lists in Java

2012-05-24T13:23:00.001-07:00

package LinkList;

/**
* @author Naveen Kumar
*/

public class LinkListTest {
static node n, root;
public static void main(String args[])
{
if(n==null)
System.out.println("node is null");
int[] elements = {1,1,2,3,2,2,5,4,4,6,5,6,7,8,7,9};

for(int i=0;i<elements.length;i++)
{
insert(elements[i], root);
display(root);
System.out.println();
}
}

static void insert(int a, node n)
{
if(root==null)
{
root = new node();
root.data = a;
}
else
{
if(a<n.data)
{
if(n.left!=null)
insert(a,n.left);
else
{
node temp = new node();
temp.data = a;
n.left = temp;
}
}
else if(a>n.data)
{
if(n.right!=null)
insert(a,n.right);
else
{
node temp = new node();
temp.data = a;
n.right = temp;
}
}
else if(a==n.data)
n.count++;
}
}

static void display(node n)
{
if(n==null)
return;
display(n.left);
System.out.print(n.data+"\t");
display(n.right);
}
}

class node
{
int data;
int count;
node left;
node right;

public node()
{
this.left = null;
this.right = null;
this.data = 0;
this.count = 0;
}
}

/*
Used traversal type is inorder traversal
as per my application requirement I skipped multiple occurances
*/
OUTPUT:

run:
node is null
1
1
1 2
1 2 3
1 2 3
1 2 3
1 2 3 5
1 2 3 4 5
1 2 3 4 5
1 2 3 4 5 6
1 2 3 4 5 6
1 2 3 4 5 6
1 2 3 4 5 6 7
1 2 3 4 5 6 7 8
1 2 3 4 5 6 7 8
1 2 3 4 5 6 7 8 9
BUILD SUCCESSFUL (total time: 0 seconds)

Data Structures (Queue operations using arrays)

2011-08-13T04:44:00.000-07:00

#include<stdio.h>
#include<conio.h>

int queue[10];
int front = -1;
int rear = -1;
int n = 9;

void queue_insert(int data)
{
     if(front==n)
    {
         printf("Queue rull");
    }
    else if(front==-1)
    {
         queue[0] = data;
         front = rear = 0;
     }
     else
     {
         queue[++rear] = data;
    }
}

void queue_delete()
{
     if(front==-1 && rear==-1)
     {
         printf("Queue empty");
         exit(0);
     }
     else if(front==rear)
     {
          printf("\n%d deleted from the queue.\n",queue[front]);
         front=rear=-1;
     }
     else
     {
     printf("%d deleted from the queue.\n",queue[front]);
     front++;
     }
}

int main()
{
    queue_insert(10);
    queue_insert(20);
    queue_delete();
    getch();
}

Data Structures (Stack operations using arrays)

2011-08-11T10:46:00.000-07:00

#include<stdio.h>
#include<conio.h>

int top = -1;
int stack[10];
void push(int data)
{
stack[++top] = data;
printf("Data pushed\n");
}

void pop()
{
if(top!=-1)
{
printf("\n%d is popped out of the stack",stack[top]);
top--;
}
else
printf("Stack empty");

}

int main()
{
push(10);
push(20);
pop();
getch();
}

Data Structures (Stack operations using linked lists)

2011-08-11T06:28:00.001-07:00

#include<stdio.h>
#include<conio.h>

/*
Define the structure of the node with the data it holds and a link to another node.
*/
struct node
{
int item;
struct node *link;
};

/*
Declare a pointer top to point the TOP of the stack. Initially the pointer top is pointing to NULL
*/
struct node *top;

/*
The push function.
*/
void push(int data)
{
//create a temporary node, add data to it, link it with the stack and update the top
struct node temp;
if(&temp!=NULL) // if node is not created, then there is no memory for new node
{
temp.item = data;
temp.link = top;
top = &temp;
printf("Data Inserted\n");
}
else
printf("Stack is full");
}

/*
The pop function
*/
void pop()
{
struct node *temp;
if(top!=NULL)//top NULL implies that stack is empty
{
temp = top;
printf("popped data is:%d",temp->item);
top = top->link;
}
else
printf("Stack empty");
}

int main()
{
push(10);
push(20);
pop();
getch();
return 0;
}

Assembly Line Scheduling Algorithm in java

2011-02-04T01:32:00.000-08:00

/**
* @author Naveen Kumar BS
* @copyright 2010
*
* Module: Assembly Line Scheduling
*
* Developed On: 03/08/2010
*
* Work: Implementing Assembly Line Scheduling.
* File Name: Fast.java
*/

import java.util.*;
class Fast
{
public static void main(String args[])
{
int[] a1={7,9,3,4,8,4},a2={8,5,6,4,5,7},t1={2,3,1,3,4},t2={2,1,2,2,1};
int e1=2,e2=4,x1=3,x2=3,f,l,k;
int[] f1,f2,l1,l2;
f1=new int[6];
f2=new int[6];
l1=new int[6];
l2=new int[6];
f1[0]=e1+a1[0];
f2[0]=e2+a2[0];
System.out.println("\n\nAssembly times for stations on line 1");
System.out.print("Station\t\t:");
for (int i=0;i<6;i++)
System.out.print(" "+(i+1));
System.out.print("\nAssembly Time\t:");
for(int i=0;i<6;i++)
System.out.print(" "+a1[i]);
System.out.println("\n\nAssembly times for stations on line 2");

//System.out.println("Assembly times for stations on line 1");
System.out.print("Station\t\t:");
for (int i=0;i<6;i++)
System.out.print(" "+(i+1));
System.out.print("\nAssembly Time\t:");
for(int i=0;i<6;i++)
System.out.print(" "+a1[i]);
System.out.println();

for(int j=1;j<6;j++)
{
if((f1[j-1]+a1[j]) <=(f2[j-1]+t2[j-1]+a1[j]))
{
f1[j]=f1[j-1]+a1[j];l1[j]=1;
}
else
{
f1[j]=f2[j-1]+t2[j-1]+a1[j]; l1[j]=2;
}
if((f2[j-1]+a2[j])<=(f1[j-1]+t1[j-1]+a2[j]))
{
f2[j]=f2[j-1]+a2[j]; l2[j]=2;
}
else
{
f2[j]=f1[j-1]+t1[j-1]+a2[j];l2[j]=1;
}
}

if(f1[5]+x1 < f2[5]+x2)
{
f=f1[5]+x1;l=1;
}
else
{
f=f2[5]+x2;l=2;
}

System.out.println("\n\n");
System.out.print("f1\t:");
for(int i=0;i<6;i++)
System.out.print(f1[i]+ " ");
System.out.println();
System.out.print("f2\t:");
for(int i=0;i<6;i++)
System.out.print(f2[i]+ " ");
System.out.println();
System.out.println();
System.out.print("l1\t:");
for(int i=1;i<6;i++)
System.out.print(l1[i]+ " ");
System.out.println();
System.out.print("l2\t:");
for(int i=1;i<6;i++)
System.out.print(l2[i]+ " ");

System.out.println();
System.out.println();
System.out.println("Entry Times e1="+e1+" and e2="+e2);
System.out.println("Exit Times x1="+x1+" and x2="+x2);
System.out.println();
System.out.println("Optimal Time is: "+f);
System.out.println("Optimal line is: "+l);

System.out.println("\n\nOptimal Path\n");
System.out.println("Line "+l+" Station "+6);
k=l;
for(int j=5;j>=1;j--)
{

if (k==1)
{
k=l1[j];
System.out.println("Line "+k+" Station "+(j)+" ");
}
else
{
k=l2[j];
System.out.println("Line "+k+" Station "+(j)+" ");
}
}
System.out.println();

}
}

Output:

READING AND WRITING CLASS OBJECTS FROM/TO FILES

2009-08-23T20:41:00.001-07:00

#include
#include
class invt
{
char name[10];
int code;
float cost;
public:
void readdata(void);
void writedata(void);
};

void invt :: readdata(void)
{
printf("Enter Name: "); scanf("%s",&name);
printf("Enter Code: "); scanf("%d",&code);
printf("Enter Cost: "); scanf("%f",&cost);
}
void invt :: writedata(void)
{
printf("%s\t%d\t%f\n",name,code,cost);
}
void main()
{
clrscr();
invt item[3];
fstream file;
file.open("stock.dat",ios::in|ios::out);
printf("Enter the details for three items\n");
for(int i=0;i<3;i++)
{
item[i].readdata();
file.write((char *) &item[i],sizeof(item[i]));
}
file.seekg(0);
printf("\n\t\tOUTPUT\n\n");
printf("Name\tCode\tCost\n");
for(i=0;i<3;i++)
{
file.read((char *) &item[i],sizeof(item[i]));
item[i].writedata();
}
file.close();
getch();
}

OUTPUT:
In the above program object is directly written in to the file but not the elements or the data directly and the data is retrieved by means of the object but not directly.

Enter details for three items
Enter Name: aaaa
Enter Code: 333
Enter Cost: 45
Enter Name: bbbb
Enter Code: 434
Enter Cost: 54
Enter Name: cccc
Enter Code: 535
Enter Cost: 65

OUTPUT

Name Code Cost
aaaa 333 45
bbbb 434 54
cccc 535 65

WRITING NUMBERS IN TO FILE

2009-08-23T20:36:00.000-07:00

#include"fstream.h"
#include"conio.h"
void main()
{
Clrscr();
float ht1[4],ht[4]={13,14,54,66};
fstream file;
file.open("aaa.a",ios::out);
file.write((char *) &ht,sizeof(ht));
file.close();
file.open("aaa.a",ios::in);
file.read((char *) &ht1,sizeof(ht1));
for(int i=0;i<4;i++)
{
printf("%f",ht1[i]);
printf("\n");
}
file.close();
getch();
}

OUTPUT:
The numbers in the floating point array ht are first converted into character type and then they are stored in the file with the file name “aaa.a” and then they are retrieved from the file with file name “aaa.a” and stored in the array of floating point ht1 and these values are printed as follows.

13
14
54
66

Finding Even of Odd without decission statements.

2009-05-10T10:53:00.000-07:00

This is a program in C to find whether the given number is an even or odd number. But no decission making statements (like if, if-else, switch, while etc..) are employed.

void main()

{

int n;

printf("Enter the n value: ");

scanf("%d",&n);

char res[2];

res[0]='e';

res[1]='o';

printf("%c",res[n%2]);

getch();

}

Output:

Enter the n value: 10

here E stands for even number and

O stands for Odd number

Implementation of mini-printf

2009-05-10T06:28:00.000-07:00

/* this is a program in C-Language to implement a printf statement*/
#include"stdio.h"
#include "stdarg.h"
int mprintf(const char *str,...);
int main()
{
     mprintf("Text is %d,%c,%d,%f",10,'a',15,2.3);
     return 0;
}

int mprintf(const char *str,...)
{
     int i=0,p;
     float f;
     char c,ch;
     va_list ap;
     va_start(ap,str);
     while(str[i]!='\0')
     {
         if(isalpha(str[i])
         {
             putchar(str[i]);
             i++;
         }
         else if(str[i]=='%')
         {
         i++;
         switch(str[i])
         {
         case 'd': p=va_arg(ap,int);printf("%d",p);break;
//instead of printf here we can use a user defined function that converts the integers into characters and prints
         case 'f': f=va_arg(ap,double);printf("%d",f);break;
//instead of printf here we can use a user defined function that converts the floating point values into characters and prints. to print characters putchar can be used.
         case 'c': c=va_arg(ap,int);putchar(c);break;
         default: putchar("%");putchar(str[i]);break;
     }
     i++;
     }
     else
     {
         puthcar(str[i]);i++;
     }
     }
     return 0;
// we can employ a count value to count the total no of values printed and can be returned here
}