C# versus C++

Although it has some elements derived from Visual Basic and Java, C++ is C#'s closest relative.

In an important change from C++, C# code does not require header files. All code is written inline.

As touched on above, the .NET runtime in which C# runs performs memory management, taking care of tasks like garbage collection. Because of this, the use of pointers in C# is much less important than in C++. Pointers can be used in C#, where the code is marked as 'unsafe', but they are only really useful in situations where performance gains are at an absolute premium.

 

Speaking generally, the 'plumbing' of C# types is different from that of C++ types, with all C# types being ultimately derived from the 'object' type. There are also specific differences in the way that certain common types can be used. For instance, C# arrays are bounds checked unlike in C++, and it is therefore not possible to write past the end of a C# array.

C# statements are quite similar to C++ statements. To note just one example of a difference: the 'switch' statement has been changed so that 'fall-through' behavior is disallowed.

 

As mentioned above, C# gives up on the idea of multiple class inheritance. Other differences relating to the use of classes are: there is support for class 'properties' of the kind found in Visual Basic, and class methods are called using the Operator rather than the :: operator.

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C# versus Java

C# and Java are both new-generation languages descended from a line including C and C++. Each includes advanced features, like garbage collection, which remove some of the low level maintenance tasks from the programmer. In a lot of areas they are syntactically similar.

 

Both C# and Java compile initially to an intermediate language: C# to Microsoft Intermediate Language (MSIL), and Java to Java bytecode. In each case the intermediate language can be run - by interpretation or just-in-time compilation on an appropriate 'virtual machine'. In C#, however, more support is given for the further compilation of the intermediate language code into native code.

 

C# contains more primitive data types than Java, and also allows more extension to the value types. For example, C# supports 'enumerations', type-safe value types which are limited to a defined set of constant variables, and 'structs', which are user-defined value types.

 

Unlike Java, C# has the useful feature that we can overload various operators.

Like Java, C# gives up on multiple class inheritance in favour of a single inheritance model extended by the multiple inheritances of interfaces. However, polymorphism is handled in a more complicated fashion; with derived class methods either 'overriding' or 'hiding' super class methods

 

C# also uses 'delegates'-type-safe method pointers. These are used to implement event handling.

 

In Java, multi-dimensional arrays are implemented solely with single-dimensional arrays (Where arrays can be members of other arrays). In addition to jagged arrays, however, C# also implements genuine rectangular arrays. 

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Type of .NET Languages

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To help create languages for the .NET Framework, Microsoft created the Common Language Infrastructure specification (CLI). The CLI describes the features that each language must provide in order to use the .NET Framework and comm6n language runtime and to interoperate with components written in other languages. If a language implements the necessary functionality, it is said to be .NET-compliant.

The .NET Framework was developed so that it could support a theoretically infinite number of development languages. Currently, more than 20 development languages work with the .NET Framework. C# is the programming language specifically designed for the .NET platform, but C++ and Visual Basic have also been upgraded to fully support the .NET framework. The following are the commonly used languages provided by the Microsoft:

• VC++

• VB.NET

.C#

• J#

• JScript .NET

 

Many third parties are writing compilers for other languages with .NET support. With CLR, Microsoft has adopted a much liberal policy. Microsoft has them selves evolved/ developed/ modified many of their programming languages which compliant with .NET CLR.

VC++

Although Visual C++ (VC++) , has undergone changes to incorporate .NET; yet VC++ also maintains its status being a platform dependent programming. Many new MFC classes have been added a programmer can choose between using MFC and compiling the program into a platform specific executable file; or using .NET framework classes and compile into platform independent MISL file. A programmer can also specify (via directives) when ever he uses "unsafe" (the code that by passes CLR, e.g. the use of pointers) code.

VB.NET

Out of ALL .NET languages, Visual Basic.NET (VB.NET) is one language that has probably undergone into the most of changes. Now VB.NET may be considered a complete Object- Oriented Language (as opposed to its previous "Half Object Based and Half Object Oriented" status).

Visual Basic .NET provides substantial language innovations over previous versions of visual basic. Visual Basic .NET supports inheritance, constructors, polymorphism, constructor overloading, structured exceptions, stricter type checking, free threading, and many other features. There is only one form of assignment: noLet of set methods. New rapid application development (BAD) features, such as XML Designer, Server Explorer, and Web Forms designer, are available in Visual Basic from Visual Studio .NET. With this release, Visual Basic Scripting Edition provides full Visual Basic functionality.

C#

Microsoft has also developed a brand new programming language C# (C Sharp). This language makes full use of .NET. It is a pure object oriented language. A Java programmer may find most aspects of this language which is identical to Java. If you are a new comer to Microsoft Technologies - this language is the easiest way to get on the .NET band wagon. While VC++ and VB enthusiast would stick to VC.NET and VB.NET; they would probably increase their productivity by switching to C#. C# is developed to make full use of all the intricacies of .NET. The learning curve of C# for a Java programmer is minimal. Microsoft has also come up with a The Microsoft Java Language Conversion Assistant-which is a tool that automatically converts existing Java-language source code into C# for developers who want to move their existing applications to the Microsoft .NET Framework.

J#

Microsoft has also developed J# (Java Sharp). C# is similar to Java, but it is not entirely' identical. It is for this reason that Microsoft has developed J# - the syntax of J# is identical to Visual J++. Microsoft's growing legal battle with Sun, over Visual J++ - forced Microsoft to discontinue Visual J++. So J# is Microsoft's indirect continuation of Visual J++. It has been reported that porting a medium sized Visual J++ project, entirely to J# takes only a few days of effort.

JScript.NET

Jscript.NET is rewritten to be fully .NET aware. It includes support for classes, inheritance, types and compilation, and it provides improved performance and productivity features. JScript.NET is also integrated with visual Studio .NET. You can take advantage of any .NET Framework class in JScript .NET.

Third-party languages

Microsoft encourages third party vendors to make use of Visual Studio. Net. Third, party vendors can write compilers for different languages ~ that compile the language to MSIL

(Microsoft Intermediate Language). These vendors need not develop their own development environment. They can easily use Visual Studio.NET as an IDE for their .NET compliant language. A vendor has already produced COBOL.NET that integrates with Visual Studio.NET and compiles into MSIL. Theoretically it would then be possible to come up with Java compiler that compiles into MSIL, instead of Java Byte code; and uses CLR instead of JVM. However Microsoft has not pursued this due to possible legal action by Sun.

Several third party languages are supporting the .NET platform. These languages include APL, COBOL, Pascal, Eiffel, Haskell, ML, Oberon, Perl, Python, Scheme and Smalltalk.

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What is Garbage Collection

When you initialize a variable using the new operator, you are in fact asking the compiler to provide you some memory space in the heap memory. The compiler is said to "allocate" memory for your variable. When that variable is no longer needed, such as when your program closes, it (the variable) must be removed from memory and the space it was using can be made available to other variables or other programs. This is referred to as garbage collection. In the past, namely in C/C++, this was a concern for programmers because they usually had to remember to manually delete such a variable (a pointer) and free its memory.

The .NET Framework solves the problem of garbage collection by letting the compiler "clean" memory after you. This is done automatically when the compiler judges it necessary so that the programmer doesn't need to worry about this issue.

Garbage collection is a mechanism that allows the computer to detect when an object can no longer is accessed. It then automatically releases the memory used by that object (as well as calling a clean-up routine, called a "finalizer," which is written by the user). Some garbage collectors like the one used by .NET, compact memory and therefore decrease your program's working set.

For most programmers, having a garbage collector (and using garbage collected objects) means that you never have to worry about deallocating memory, or reference counting objects, even if you use sophisticated .data .structures. It does require some changes in coding style, however, if you typically deallocate system resources (file handles, locks, and so forth) in the same block of code that releases the memory for an object. With a garbage collected object you should provide a method that releases the system resources deterministically (that is, under your program control) and let the garbage collector release the memory: when it compact the working set.

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What is Common Language Infrastructure (CLI)

The Common Language Infrastructure (CLI) is an open specification developed by Microsoft that describes the executable code and runtime environment that allows multiple high-level languages to be used on different computer platforms without being rewritten for specific architectures. CLR is Microsoft Commercial implementation of Common Language Infrastructure (CLI).

The Common Language Infrastructure (CLI) is a theoretical model of a development platform that provides a device and language independent way to express data and behavior of applications.

While the CLI primarily supports Object Oriented Programming (OOP) languages, procedural and functional languages are also supported. Through the CLI, languages can interoperate with each other and make use of a built-in garbage collector, security system, exception support, and a powerful framework.

  

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What is Just in Time Compiler(JIT)

Machines cannot run MSIL directly. JIT compiler turns MSIL into native code, which is CPU specific code that runs on the same computer architecture as the JIT compiler. Because the common. Language runtime supplies a JIT compiler for each supported CPU architecture, developers can write a set of MSIL that can be JIT-compiled and run on computers with different architectures.

However, your managed code will run only on a specific operating system if it calls platform specific native APIs, or a platform-specific class library.

JIT compilation takes into account the fact that some code might never get called during execution. Rather than using time and memory to convert all the MSIL in a portable executable (PE) file to native code, it converts the MSIL as needed during execution and stores the resulting native code so that it is accessible for subsequent calls.

The loader creates and attaches a stub to each of a type's methods when the type is loaded. On the initial call to the method, the stub passes control to the JIT compiler, which converts the MSIL for that method into native code and modifies the stub to direct execution· to the location of the native code. Subsequent calls of the JIT -compiled method proceed directly to the native code that was previously generated, reducing the time it takes to JIT-compile and run the code.

Managed and Unmanaged Code

Managed code is code that is written to target the services of the common language runtime. In order· to target these services, the code must provide a minimum level of information (metadata) to the runtime. All C#, Visual Basic .NET, and JScript .NET code is managed by default. Visual Studio .NET C++ code is not managed by default, but the compiler can produce managed code by specifying a command-line switch (/CLR).

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What is Visual Studio .NET

The following is the list of some of the features of Visual Studio .NET:

 

1. Visual studio automates the step required to compile source code.

 

2. The Visual Studio text editor is very intelligent; it can detect errors and suggests code as appropriate as you required.

 

3. The Visual Studio designer for Windows Forms and Web Forms applications, allowing simple Drag and drop design of User Interface elements.

 

4. The Visual Studio contains many powerful tools for visualizing and navigating through the elements of our projects, whether they are C# code files or other resources such as bitmap images or sound files.

 

5. The Visual Studio enables us to use advance debugging techniques when developing projects, such as ability to step through code one instruction at a time while keeping an eye on the state of our application. 

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What is Common Type System (CTS)

The language interoperability, and .NET Class Framework, are not possible without all the language sharing the same data types. What this means is that an "int" should mean the same in VB, VC++, C# and all other .NET compliant languages. Same idea follows for all the other data types. This is achieved through introduction of Common Type System (CTS).

Common type system (CTS) is an important part of the runtimes support for cross language integration. The common type system performs the following functions:

• Establishes a framework that enables cross-language integration, type safety, and high performance code execution.

• Provides an object-oriented model that supports the complete implementation of many programming languages.

The common type system supports two general categories of types:

1. Value types

Value types directly contain their data, and instances of value types are either allocated on the stack or allocated inline in a structure. Value types can be built-in, user-defined or enumerations types.

2. Reference types

Reference types stores a reference to the value's memory address, and are allocated on the heap. Reference types can be self-describing types, pointers types, or interface types. The type of a reference type can be determined from values of self-describing types. Self-describing types are further split into arrays and class types are user-defined classes, boxed value types, and delegates. 

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What is Microsoft Intermediate Language (MSIL)

A .NET programming language (C#, VB.NET, J# etc.) does not compile into executable code; instead it compiles into an intermediate code called Microsoft Intermediate Language (MSIL). As a programmer one need not worry about the syntax of MSIL - since our source code in automatically converted to MSIL. The MSIL code is then send to the CLR (Common Language Runtime) that converts the code to machine language which is then run on the host machine.

MSIL is similar to Java Byte code. A Java program is compiled into Java Byte code (the .class file) by a Java compiler, the class file is then sent to JVM which converts it into the host machine language.

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