Computer Programming

Thursday, January 30, 2014

January 30, 2014

Reference Data Types in Java Programming

Any type of storage that stores an address or we can say reference of object in memory, called Reference data type. Java like other language have also some reference data types discussed in the article.

Broadly a reference in Java is a data element whose value is an address of a memory location. Arrays (a group of similar data items), classes (a blue print of some entity e.g. a student) and interfaces are reference type. The value of reference type variable, in contrast to that of primitive type, is a reference to (an address of) the value or set of values represented by variables.

A reference is called a pointer, or memory address in other language. The java programming language does not support the explicit use of addresses like other languages do. You use variable’s name instead.

An importance reference type that you use in Java is String type. The String type lets you create variables that can hold textual data e.g. “Mohan”, TZ194”, “194ZB”, “234” etc. Anything that you enclose in double quotes is treated as text in Java.

January 30, 2014

Create PHP Array in PHP Programming

Create PHP array :-
We have following methods to create an array in PHP.
• To assign index and key manually to the variable: - In this method we have to provide a specific index value as well as key value to the variable. This can be understood with the help of example.
Let we want an array named “record” to store different information of students such as name, age , id, and marks. Here the variable “record” act as an array and store all these information in following way.

In this example we use an array variable $record to store different elements. Now we have following properties this PHP array.

• Index range for this array is 0-3.where minimum index is 0 and maximum index is 3;

• Maximum item that this array can store is 4.

• A PHP array can store different type of elements like integer or string or double etc. because php takes the type of data automatically corresponding to that.

• In above program we use the function print_r() which is used to print values store in array variable.

In this example we used a key in stand of index. PHP provide this facility to make the array calculation much easy and user-friendly. The array which uses keys to hold the value is called associative array.

• To use range() function:- If we want to create an array with a specific range like for integer such as 100-500 or for float 4.6-90.6 or for string like b-k then we can create an array by using range function. Syntax of this method is following

Range (string value, ending value, difference);

This could be understood with the help of example.

• To use array () function: - This functions is used to make an array in php. The syntax of this fictional is follows.

Array array ([ mixed $... ] )

This array function takes mixed type of variables and prepares an array for us.

This can be understand with the help of following codes.

$name=array(“jack”, “jon”,”weilems”);

Or this can be use for associative array such as:-

$record=array(name->”jack” ,roll->5, marks->45.9, address->”new york”);

ASP.NET

January 30, 2014

How to use TextChanged event of TextBox with AutoPostBack in ASP.NET

ASP.NET application works on AutoPostBack model, i mean, if we want to run code behind event like TextChanged event then we must set AutoPostBack property is true.
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default3.aspx.cs" Inherits="Default3" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title></title>
</head>
<body>
<form id="form1" runat="server">
<div>
Search Item<asp:TextBox ID="TextBox1" runat="server"
AutoPostBack="True" Width="174px" ontextchanged="TextBox1_TextChanged"></asp:TextBox>
<br />
<br />
</div>
<asp:Label ID="Label1" runat="server"></asp:Label>
</form>
</body>
</html>
Code Behind Code

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

public partial class Default3 : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{

}
protected void TextBox1_TextChanged(object sender, EventArgs e)
{
string[] arr = { "jacob", "lefore", "martin" };

foreach (string item in arr)
{
if (item==TextBox1 .Text)
{
Label1.Text = item;

}
}

}
}

Output

This example shows that TextChanged event occurs when user focus out from the TextBox. You can search item on TextChanged event.

January 30, 2014

Algorithmic Notation in DataStructure, C Programming

Algorithm is a sequential, finite non-complex step-by-step solution, written in English like statements, to solve a problem. Here we can consider some points about the algorithmic notation, which are helpful in writing algorithms to understand the basic data structure operations clearly. Algorithm writing is first step in implementing the data structure.

1.Name of the algorithm and parameters: Name of the algorithm may be written in capital letters and the name is chosen according to the problem or operation specification. The name may depict the work done by algorithm is called can be given as parameter names immediately followed by name of the algorithm in a pair of parenthesis.
e.g. TRAVERSELIST (LIST, SIZE)
LINEARSEARCH (LIST, SIZE, ITEM)

The name of algorithm serves the purpose of start for algorithm and it is the heading of algorithm, and further statements of algorithm are written after the heading.
s using any of the programming languages.

2.Comments: The comments that are necessary to explain the purpose of algorithm or the things used in an algorithm in detail as non-executable statements of a program are written in a pair of square brackets.
e.g. LINEARSEARCH (LIST, SIZE, ITEM)
[Algorithm to search an ITEM in the LIST of size SIZE].

3.Variable names: The variable names are written in capital letters without any blank spaces within it. Underscore (_) may be used in case of multi-word names to separate the words. The name should start with an alphabet and may have any number of further alphabets or numbers.
e.g. LIST, SIZE, ITEM, NUM1, FIRST_NUM etc.
Single letter names like I, J, K can be used for index numbers.

4.Assignment operator: To set the values of a variable an assignment operator—may be used or = sign along with SET and value may be used. In this book—is used.
e.g. SET COUNT=0, COUNT+1 etc.
The second type is most commonly used.

5.Input and Output: To input the value of a variable Read: and to output the values of variable Write: are used. The message to be outputted may be placed between single quotes ‘ ‘.
e.g. Read: NUM
Write: The Value is’, SUM
Write: NUM etc.

6.Sequential statements are written one after the other, usually in separate lines. If two statements are to be written on the same line they may be separated by means of comma,. Arithmetic operators +,-, *, /, % can be used for addition, subtraction, multiplication, division, mod operation respectively, to write arithmetic expressions.
e.g. SUM—0; NUM—15
SUM—SUM+NUM
Write: ‘Sum is’, SUM

7.Selective statements or conditional statements can be written using If-Then:, If-Then: Else:. The relational operators >,>=<,<=,<>,= can be used for greater than, greater than or equal, less than, less than or equal, not equal, equal respectively. For logical connection of two conditions AND, OR can be used. NOT can be used to negate the condition.

8.Repetitive or Iterative statements can be written between Repeat For … [Endo For] or Repeat While …[End of While]. Repeat For is used for the purpose of repeating the statements for fixed number of times where as Repeat while is used to repeat the statements till a condition is true.

9.Exit is used terminate the Algorithm and Return may be used to return a value from the algorithm.

10.The array elements can be referred by means of the Name of the array and subscript in a pair of square brackets. The fields of a static struct can be referred by means of placing the name of the struct variable, a. (dot) and field name. The fields of a dynamic struct can be referred by means of placing the name of struct variable, (arrow) and field name. The arrow operator is framed as a combination of – (minus) and > (greater than operators).
e.g. LIST[1], LIST[I], LIST[J] etc.
NODE--->LINK, NODE--->INFO etc.
EMP.ENO, EMP.SALARY etc.

Wednesday, January 29, 2014

Java Programming

January 29, 2014

Character and Boolean Data Types used in Java Programming

Java programming have some more data types for storage of single character and even true/false values. These data types are called Character and Boolean in programming language.

Character Type

The character data type (char) data type of Java is used to store characters. A character in Java can represent all ASCII (American standard Code for Information Interchange) as well as Unicode characters.

The Unicode character representation code can represent nearly all languages of world such as Hindi, English, German, French, Chinese, and Japanese etc. And because of Unicode character, size of char data type of Java is 16 bits i.e., 2 bytes in contrast to 1 byte characters of other programming languages that support ASCII.

Type: Char (Single Character)
Size: 16bits (2 bytes)
Range: 0 to 65536

Boolean Type

Another type of the primitive data type is Boolean. A Boolean value can have one of two values: true or false. So this data type is used to store such type of values.

In a Java program, the words true and false always mean these Boolean values. The data type Boolean is named after a nineteenth century mathematics- George Boole, who discovered that a great many things can be done with true/false value. A special branch of algebra Boolean algebra, is based on Boolean values.

Type: Boolean (Logical values)
Size: reserve 8 bits uses 1 bit
Range: true or false

Following tables lists examples of various data items of different data types. Here are some examples of literal values of various primitive types:

Character and Boolean Data Types used in Java Programming

January 29, 2014

Draw graphics in ASP.NET

You can draw graphics on browser window using Graphics class. This class exists in System.Drawing namespace. It provide different types of graphics methods, such as DrawArc, DrawImage, DrawIcon, DrawLine and many more. Graphics class hold pen instance for creating graphics onto the screen.

Algorithm Behind the drawing

Step-1 : First define the graphics area on browser window using Bitmap class.
Step-2 : Create instance of Graphics class and initialize with Bitmap class instance.
Step-3 : Create Pen class object with specified color and width.
Step-4 : Create starting point and ending point using Point class.
Step-5 : Draw graphics and save into Bitmap instance.

Lets take an simple example of drawing Line , Rectangle in asp.net

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default3.aspx.cs" Inherits="Default3" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title></title>
</head>
<body>
<form id="form1" runat="server">
<div>

</div>
<asp:Image ID="Image1" runat="server" Height="83px" Width="95px" />
</form>
</body>
</html>

CodeBehind Code Draw Rectangle

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Drawing;
using System.Drawing.Imaging;

public partial class Default3 : System.Web.UI.Page
{

protected void Page_Load(object sender, EventArgs e)
{
Bitmap bmp = new Bitmap(500,200);
Graphics g = Graphics.FromImage(bmp);
g.Clear(Color.Green);
Pen p1 = new Pen(Color.Orange, 3);

g.DrawRectangle(p1, 20, 20, 80, 40);

string path = Server.MapPath("~/Image/rect.jpeg");
bmp.Save(path, ImageFormat.Jpeg);

Image1.ImageUrl = "~/Image/rect.jpeg";

g.Dispose();
bmp.Dispose();

}
}

Code Generating the following output

CodeBehind Code for Draw Line

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Drawing;
using System.Drawing.Imaging;

public partial class Default3 : System.Web.UI.Page
{

protected void Page_Load(object sender, EventArgs e)
{
Bitmap bmp = new Bitmap(500,200);
Graphics g = Graphics.FromImage(bmp);
g.Clear(Color.Green);
Pen p1 = new Pen(Color.Orange, 3);

g.DrawLine(p1, 20, 20, 100, 100);
string path = Server.MapPath("~/Image/line.jpeg");
bmp.Save(path, ImageFormat.Jpeg);

Image1.ImageUrl = "~/Image/line.jpeg";

g.Dispose();
bmp.Dispose();

}
}

Code Generating the following output

January 29, 2014

Operations on Data Structures, C programming

Basically there are six operations one can do on the data structures. They are Traversing, Searching, Sorting, Insertion, Deletion and Merging.

1. Traversing: Basically to process a data structure if every element of data structure is visited once and only once, such type of operation is called as TRAVERSING. For example to display all the elements of an array, every element is visited once and only once, so it is called as traversing operation.
Suppose we have an array of 20 students’ average makes, and if we need to calculate the average of group, we visit (read) each individual average and accumulate (sum) them. Then we will find the array are visited once and only once. Then it is traversing of an array.

2. Insertion: When an element of the same type is added to an existing data structure, the operation we are doing is called as Insertion operation. The element can be added anywhere in the data structure in the data structure. When the element is added in the end it is called as special type addition, Appending. In case of adding an element to the data structure we may come across ‘Overflow’ If the size of the data structure is fixed and it is full, then if we try insertion operation on the data structure it is said to be overflow of data structure or the data structure is full.

Suppose we have an array of size 20 used to store marks obtained by the students in Computer Science subject. If we have already added 15 students’ marks according to an ascending order, then we can add another student marks at appropriate place, by shifting the already stored element accordingly. Then it is called Insertion operation.

3. Deletion: When an element is removed from the data structure, the operation we are doing is called as Deletion operation. We can delete an element from data structure from any position. In case of deleting an element from the data structure we may come across ‘Underflow’. If no elements are stored in the data structure, then if we try deletion operation on the data structure it is said to be underflow of data structure or data structure is empty.

Suppose we have an array of size 20 used to store marks obtained by the students in Computer Science subject. If we have already added 15 student s’ marks according to an ascending order, then we can delete one student’s marks from any place, by shifting the already stored elements accordingly. Then it is called Deletion operation.

4. Searching: When an element is checked for its presence in a data structure, that operation we are doing is called as ‘searching’ operation. The element that is to be searched is called as key element. The searching can be done using either ‘linear search’ or ‘binary search’.

Suppose we have an array of size 10 and assume elements stored are 1,2,3,23,34,54,56,21,32,33 and assume we want to search the number 23. So here the number ‘23’ is key element. The key is searched through the array starting from the first element till end. When it is compared with the fourth element in it is present in the list (array) of numbers. So search is successful. This type of searching is called as Linear Search because the last element. In order to apply linear search, the list may not be in any particular order but when binary search is applied the list must be an ordered one.

5. Sorting: When all the elements of array are arranged in either ascending or descending order, the operation used to do this process is called as Sorting. The Sorting can be done using Insertion, Selection or Bubble sort techniques.
Suppose we have an array of size 10 and assume elements stored are 1,2,3,23,34,54,56,21,32,33. The elements of the array are not in proper order. If they are arranged in ascending order the list (array) becomes 1,2,3,21,23,32,34,54,56.

6. Merging: When two lists List A and List B of size M and N respectively, of same type of elements, clubbed or joined to produce the third list, List C of size (M+N), and the operation done during the process is called as Merging.

Suppose we have a list of size 6, containing the elements 1,2,3,4,71,87 and we have another list of size 5, containing the elements 9,13,21,65,67. Here both the lists are in ascending order. We can produce the third list of size 11 that will also be in ascending order, containing the element 1,2,3,4,9,13,21,65,67,71,87. The third list is called the merged list of first and second lists. In order to merge two lists into single list one needs to compare each element from both the lists and one of them will go the merged list.