Deep Dive

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2018-08-22T09:35:00.001-07:00

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C++ STL - 1

2011-07-17T13:45:00.000-07:00


#include <vector>
#include <list>
#include <iostream>
using namespace std ;

void main()
{
     vector<int> v ;
     v.push_back(10);
     v.push_back(20);
     v.push_back(30);
 
     // Using iterator
     vector<int>::iterator  i = v.begin() ;
     for ( ; i != v.end() ; i++ ) {
            cout << *i << endl ;
     }

     list l ;
     l.push_back(10);
     l.push_back(20);
     l.push_back(30);
 
     // Using iterator
     list<int>::iterator  j = v.begin() ;
     for ( ; j != v.end() ; j++ ) {
            cout << *j << endl ;
     }
}

C# Iterator

2010-11-26T22:21:00.001-08:00

C# 2.0 has lot of syntactical sugar. One of them is C# iterator that makes the implementation of Iterator design pattern for the custom collection classes extremely easy so that the collection class object can be used with foreach statement. Here is the example:


    public class MyArrayList
    {        
        private int[] arr = new int[3];

        public MyArrayList()
        {
            arr[0] = 10;
            arr[1] = 20;
            arr[2] = 30;
        }

        public IEnumerable<int> GetIterator()
        {
            for (int i = 0; i < arr.Length; i++)
            {
                yield return arr[i];
            }
        }
    }

    class Program
    {
        static void Main(string[] args)
        {
            MyArrayList a = new MyArrayList();
            foreach (int item in a.GetIterator())
            {
                Console.WriteLine(item);
            }
        }
    }

C# foreach demystified

2010-11-26T05:36:00.000-08:00


List<string> cities = new List<string>() ;
cities.Add ( "Bangalore" ) ;
cities.Add ( "Mumbai" ) ;
cities.Add ( "Hyderabad" ) ;
cities.Add ( "Nagpur" ) ;

foreach ( string city in cities )
{
       Console.WriteLine ( city ) ;
}

C# compiler compiles the foreach to the following code:


IEnumberable<string> en = cities ;
IEnumerator<string> et = en.GeEnumerator( ) ;
while ( et.MoveNext( ) )
{
     string city = et.Current ;
     Console.WriteLine ( city ) ;
}

Code Access Security in .NET

2010-11-19T21:54:00.000-08:00

When we run an unmanaged application in Windows, the code gets all the privileges our user account has. If we accidently run a virus or a trojan horse, the application can do anything our user account has permissions to do. So we are forced to log on with minimal privileges to restrict application permissions.

Code Access Security (CAS) in .NET Framework enables us to control the permissions that individual managed applications have. If a friend sends a .NET framework application, we can restrict it to opening a window and prompting us to open and save files and nothing else. The application would not be able to send emails, upload files to a Web Site, or create files, even if we are logged on as an Administrator. CAS enables user to restrict on a very granular level what managed code can do.

As a developer, we must understand how to create applications that work even when some permissions are restricted. We can also use CAS to improve our application's security by restricting which callers can use our code and forcibly limiting our application to a restricted permission set.

Twitter Client in .NET

2010-03-24T03:17:00.000-07:00


using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Net;
using System.Xml.Linq;

namespace TwitterClient
{
    class Tweet
    {
        public string CreatedAt { get; set; }
        public string Text { get; set; }
    }

    class Program
    {
        static void Main(string[] args)
        {
            WebClient client = new WebClient();
            string xml = client.DownloadString("http://www.twitter.com/statuses/user_timeline.xml?id=shakeel_ali");

            XElement document = XElement.Parse(xml);
            string nm = document.GetDefaultNamespace().NamespaceName;

            Tweet[] tweets = (from item in document.DescendantsAndSelf(XName.Get("status", nm))
                                     select new Tweet()
                                     {
                                         CreatedAt = item.Element(XName.Get("created_at", nm)).Value,
                                         Text = item.Element(XName.Get("text", nm)).Value,
                                     }).ToArray();

            foreach (var tweet in tweets)
            {
                Console.WriteLine(tweet.CreatedAt);
                Console.WriteLine();
                Console.WriteLine(tweet.Text);
                Console.WriteLine("----------------------------");
                Console.WriteLine();
            }

        }
    }
}

How many .NET frameworks are there?

2010-03-15T09:20:00.000-07:00

1. Microsoft .NET Framework: For building Desktop Applications, Web Applications, and Distributed Applications. (Linux version: Mono Runtime)

2. Microsoft .NET Compact Framework: Mobile or Embedded Applications.

3. Microsoft .NET Micro Framework: For smaller, less expensive, and more resource-constrained devices requiring only a few hundred kilobytes of RAM and an inexpensive processor.

4. Microsoft Silverlight: For building Rich Internet Applications that runs inside the borwsers' sandbox. (Linux version: Moonlight)

Difference between Web Server and Application Server

2010-03-15T09:08:00.001-07:00

Web Server: Handles HTTP protocol, Handles Web Sites, Provides HTTP security features, Caching, etc. related to HTTP requests.

Application Server: Provides Object Pooling, Distributed Transaction, Message Queuing, Events, Remote Access, etc. services required by business applications running as distributed systems on intranet or internet.

AJAX

2010-03-14T22:00:00.000-07:00

Asynchronous JavaScript + XML, while not a technology in itself, is a term coined in 2005 by Jesse James Garrett, that describes a "new" approach to using a number of existing technologies together, including: HTML or XHTML, Cascading Style Sheets, JavaScript, The Document Object Model, XML, XSLT, JSON and the XMLHttpRequest object. When these technologies are combined in the AJAX model, web applications are able to make quick, incremental updates to the user interface without reloading the entire browser page. This makes the application faster and more responsive to user actions.

You can read more here...

A nice introduction to JavaScript

2010-03-14T21:42:00.000-07:00

An Introduction to JavaScript

Want to learn Java on your own?

2010-03-14T21:33:00.000-07:00

Go for

Thinking in Java

When to use an interface?

2010-03-14T10:29:00.001-07:00

Interface is used to create an abstraction. Abstraction is used to develop a code that is independent of the code that is calls to.

For example:


interface ISorting {
 void sort() ;
}

class Caller {
 static void makeCall ( ISorting s ) {
  s.sort() ; 
 }
}

Here the Caller class makeCall() method uses an abstraction named ISorting to call the sort() method. ISorting doesn't implement any sorting logic in its sort() method. Still the compiler compiles this code. But the compiler compiles it as late-bound call. The call is resolved at runtime depending upon the reference of the object received in s. The object reference must be of the class that implements that abstraction. Such a class is called implementation.

For example:


class MergeSort implements ISorting {
 public void sort() {
  // Merge sort implementation
 }
}
class BubbleSort implements ISorting {
 public void sort() {
  // Bubble sort implementation
 }
}

class Program {
 static void main ( String[] args ) {
  // Here sort() method of the MergeSort class will be called by Caller.makeCall().
  Caller.makeCall ( new MergeSort() ) ; 
  // Here sort() method of the BubbleSort class will be called by Caller.makrCall().
  Caller.makeCall ( new BubbleSort() ) ; 
 }
}

With the help of abstract the Caller.makeCall() can call into different implementation at runtime as it does'nt depend on implemenation at compile time. This way Caller.makeCall() can be extended by adding new implementation.

Why no Extension Properties?

2010-03-14T07:42:00.000-07:00

Why no Extension Properties?

Difference between Nested Class and Inner Class in Java

2010-03-12T23:54:00.000-08:00

- A non-static class within another class is called Inner class.
- A static class within another class is called Nested class or static Inner class.

For example:


class Outer {
 class Inner {
 } 
 static class Nested { 
 }
}

- Inner class object must be created using Outer class object.
- Nested class object is created without using Outer class object.

For example:


public class Program {
 public static void main( String[] args ) {
  Outer o = new Outer() ;

  Outer.Inner i = o.new Inner() ;

  Outer.Nested n = new Outer.Nested() ;
 }
}

- Inner class object holds the reference of Outer class object that has created it.
- Nested class object do not hold reference of Outer class object, unless explicitly passed and stored.

- Hence Inner class object can access instance data members and methods of its own as well as of the Outer class object's whose reference it holds.

For example:


class Outer {
 int x ;
 Outer ( int x ) {
  this.x = x ;
 }

 class Inner {
  int y ;
  Inner ( int y ) {
  this.y = y ;
 }

 void print() {
  System.out.println ( x + " " + y );
  }
 }

 static class Nested { 
  int z ;

  Nested ( int z ) {
   this.z = z ;
  }

  void print() {
   System.out.println ( z );
  }
 }
}

public class Program {
 public static void main( String[] args ) {
  Outer o = new Outer(10) ;

  Outer.Inner i = o.new Inner(20) ;
  i.print() ; // Output: 10 20

  Outer.Nested n = new Outer.Nested(30) ;
  n.print() ; // Output: 30
 }
}

Implementation of Stack Data Structure in Java

2010-03-12T23:02:00.000-08:00


// Stack.java

package com.leadows.datastructure ;

// Stack is a generic class so that it can hold any type of object
public class Stack<T> {
 // array reference
 private T[] arr ; 

 // top to keep track of last element
 private int top = -1 ; 

 public Stack(int size) {
  // creates array
  arr = new T[size] ; 
 }

 public void push(T item) throws Exception {
  // bounds check
  if ( top < arr.Length-1 ) { 
   // store the item
   arr[++top] = item ; 
  } else {
   throw new Exception("Stack is Full" ) ;
  }
 }

 public T pop()  throws Exception {
  // bounds check
  if ( top > -1 ) { 
   // return the value
   return arr[top--] ; 
  } else {
   throw new Exception("Stack is Empty" ) ;
  }
 }

 public int getTop() {
  return top ;
 }
}

// Program.java

import com.leadows.datastructure.* ;

public class Program {
 public static void main ( String[] args ) {
  // create stack object
  Stack<int> s = new Stack<int>() ; 
  s.push ( 100 ) ;  
  s.push ( 200 ) ;  
  s.push ( 300 ) ;  
  System.out.println ( s.pop() ) ;
 }
}

Processor Count and Debugging Parallel Applications

2010-03-12T00:08:00.000-08:00

CPU frequencies will no longer increase, instead more processors or cores will be available on our machines to conserver power and increase processing scalability. Hence modern development requires the use of parallelism. There is no longer any excuses for us as developers. For .NET developers, this is an exciting time for parallel programming. The. NET Framework 4 has added the Task Parallel Library.

FAQs

Q. How to get processor count?
A. Environment.ProcessorCount

Q. How to debug Parallel Applications?
A. Debugging Parallel Applications

Web Form Data Visualization and Security

2010-03-11T05:55:00.000-08:00

Data Access Tutorials

Security Tutorials

ASP.NET: Web Site Project vs. Web Application Project

2009-08-24T09:35:00.000-07:00

Following are the 2 great posts to understand the differences between the Web Site Project and
Web Application project in Visual Studio 2005 or 2008:

http://vishaljoshi.blogspot.com/2009/08/web-application-project-vs-web-site.html
http://vishaljoshi.blogspot.com/2009/07/appcode-folder-doesnt-work-with-web.html

.NET: Learn to develop a mini web server

2009-05-06T09:20:00.000-07:00

The ASP.NET Cassini Web Server Sample is a sample web server written using the Microsoft .NET Framework, and demonstrates hosting ASP.NET using the ASP.NET hosting APIs (System.Web.Hosting). Goog for Cassini web server source code.

.NET: References are not Addresses (Pointers)

2009-05-01T03:07:00.000-07:00

Read the following post to understand what does references mean in .NET:
http://blogs.msdn.com/ericlippert/archive/2009/02/17/references-are-not-addresses.aspx

JavaScript: Namespace, Class, Object

2009-04-08T18:16:00.001-07:00

In JavaScript, you can create Namespaces, Classes, Instance Data Members, Instance Methods and Objects. But the way to create is very different than in languages like C++, Java and C#. Here is the C# class,



class Point2D
{
        // Instance Fields
 private int _x, _y ;

        // Instance Methods
 public Point2D ( int x, int y )
 {
  _x = x ;
  _y = y ;
 }
 public int X
 {
  get { return _x ; }
  set { _x = value ; }
 }
 public int Y
 {
  get { return _y ; }
  set { _y = value ; }
 }
 public void Offset ( int ox, int oy )
 {
  _x += ox ; 
  _y += oy ; 
 }
}

// Create Object
Point2D p = new Point2D() ;

Here is the equivalent JavaScript class,



// Create Namespace
var GUI = { } ;

// Class and Constructor
GUI.Point2D = function( int x, int y ) {
        // Instance Fields or Data Members
 this._x = x ;
 this._y = y ;
}

// Instance Methods
GUI.Point2D.prototype = {
 getX : function() {
  return this._x ;
 },

 setX : function(x) {
  this._x = x ;
 },

 getY : function() {
  return this._y ;
 },

 setY : function(y) {
  this._y = y ;
 },

 offset : function(ox, oy) {
  this._x += ox ;
  this._y += oy ;
 }
}

// Create Object
var p = new GUI.Point2D() ;

C++: Good Book

2009-03-31T18:21:00.000-07:00

The effective presentation, along with dozens of helpful code examples, make this book a standout.
Thinking in C++ by Bruce Eckel

JavaScipt: Object-oriented Programming

2009-03-31T17:47:00.000-07:00

In year 2002, I wrote substantial amount of JavaScript code for a web site. The JavaScript expert in our team reviewed the code and didn't accept it just because was not object oriented. I was under impression that JavaScript is a non-OO language as there is no concept of class, inheritance and polymorphism in JavaScript. Even no JavaScipt book mentioned these concepts. If you want to learn object-oriented JavaScript to develop maintainable JavaScript and AJAX applications, here is the link...

OO JavScript