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JIT complier

In computing, just-in-time compilation(JIT), also known as dynamic translation, is a method to improve the

runtime performance ofcomputer programs. Traditionally, computer programs had two modes of runtime operation,

eitherinterpreted or static (ahead-of-time) compilation.[citation needed]

Interpreted code is translated from a high-level

language to a machine code continuously during every execution, whereas statically compiled code is translated into

machine code before execution, and only requires this translation once.

JIT compilers represent a hybrid approach, with translation occurring continuously, as with interpreters, but with

caching of translated code to minimize performance degradation. It also offers other advantages over statically

compiled code at development time, such as handling of late-bound data types and the ability to enforce security

guarantees

Common Language Runtime

The Common Language Runtime (CLR) is an Execution Environment . It works as a layerbetween Operating Systems and the applications written in .Net languages that conforms to

the Common Language Specification (CLS). The main function of Common Language Runtime(CLR) is to convert the Managed Code into native code and then execute the Program. The

Managed Code compiled only when it needed, that is it converts the appropriate instructionswhen each function is called . The Common Language Runtime (CLR) 's Just In Time (JIT)

compilation converts Intermediate Language (MSIL) to native code on demand at application runtime.

During the execution of the program ,the Common Language Runtime (CLR) manages

memory, Thread execution, Garbage Collection (GC) , Exception Handling, Common Type

System (CTS), code safety verifications, and other system services. The CLR ( CommonLanguage Runtime ) defines the Common Type System (CTS), which is a standard type systemused by all .Net languages . That means all .NET programming languages uses the same

representation for common Data Types , so Common Language Runtime (CLR) is a language-independent runtime environment . The Common Language Runtime (CLR) environment is also

referred to as a managed environment, because during the execution of a program it also controlsthe interaction with the Operating System. In the coming section you can see what are the main

functions of Common Language Runtime (CLR

SIDE by Side execution

Side by side execution means. two or more same dll with different versions reside in machinewhich is stored in the windows/assembly folder, the client application use this dll depending onthere requirement. old application use the old dll and new application build with new dll will use

the new both applications can run that is called side by side executtio

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DLL HELL

dll Hell refers to a set of problems caused when multipleapplications attempt to share a common component like adynamic link library (DLL). The reason for this issue was

that the version information about the differentcomponentsof an application was not recorded by the system.

.Net Framework provides operating systems with a GlobalAssembly Cache. This Cache is a repository for all the.Netcomponents that are shared globally on a particularmachine. When a .Net component is installed onto themachine, the Global Assembly Cache looks at its version,

its public key, and its language information and createsastrong name for the component. The component is thenregistered in the repository and indexed by its strongname, so there is no confusion between different versionsof the same component, or DLL.

DLL Hell Example :- This is a problem in loading aspecific dll

(class id, version number, path etc). For example, if Ibuild test.dll v1.0.0.0 and deploying it in c:\MyProg. Myapplication App1 and App2 are using the methods in thatdll. And there is a requirement to change something inApp1and I supposed to change test.dll also for the samerequirement. Once I finished with all my changes, I willbedeploying them in the appropriate locations. Now, theolder

dll will be overwritten. And my App2 will look fortest.dllof older version and since it is not there it will notwork. This is a scenario for dll hell issue..Net Framework provides operating systems with a GlobalAssembly Cache. This Cache is a repository for all the.Netcomponents that are shared globally on a particular

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machine. When a .Net component is installed onto themachine, the Global Assembly Cache looks at its version,its public key, and its language information and createsastrong name for the component. The component is then

registered in the repository and indexed by its strongname, so there is no confusion between different versionsof the same component, or DLL.

Array List :http://vb.net-informations.com/collections/vb.net_ArrayList.htm

Public Class Form1Private Sub Button1_Click(ByVal sender As System.Object,

ByVal e As System.EventArgs) Handles Button1.Click

Dim i As IntegerDim ItemList As New ArrayList()ItemList.Add("Item4")ItemList.Add("Item5")ItemList.Add("Item2")ItemList.Add("Item1")ItemList.Add("Item3")MsgBox("Shows Added Items")For i = 0 To ItemList.Count - 1

MsgBox(ItemList.Item(i))Next'insert an itemItemList.Insert(3, "Item6")'sort itemms in an arraylist

ItemList.Sort()'remove an itemItemList.Remove("Item1")'remove item from a specified indexItemList.RemoveAt(3)MsgBox("Shows final Items the ArrayList")For i = 0 To ItemList.Count - 1

MsgBox(ItemList.Item(i))Next

End SubEnd Class

Ienumerator

http://www.vbforums.com/showthread.php?t=429002

http://visualbasic.about.com/od/usingvbnet/a/ienumble.htm

also see the code I downloaded in IDM

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Icompare Interface

http://support.microsoft.com/kb/321292

Private Class sortYearDescendingHelper : Implements IComparer

Function Compare(ByVal a As Object, ByVal b As Object) As Integer Implements

IComparer.CompareDim c1 As car = CType(a, car)

Dim c2 As car = CType(b, car)

If (c1.year < c2.year) ThenReturn 1

End If

If (c1.Year > c2.Year) Then

Return -1Else

Return 0End If

End FunctionEnd Class