How a DotNet Program Execute ?

To understand how a DotNet program execution takes place we have to do the comparison between pre-Dotnet program execution with DotNet program execution. So before DotNet came into existence, we used to build the application using other programming languages like C++ or VB6. 

Let's, for example, build an application using VB6 and compile it using a language compiler then an assembly gets generated with .dll or .exe extension depending on the type of application. This assembly is in Native code or Machine code format. We have to do the compilation because our operating system doesn't understand high-level programming languages, they only understand binary code of 0s and 1s. So basically we deploy that assembly onto the system to get executed which is nothing but a native code. 

Now lets us understand what naive code means? Suppose you have Windows operating system and now you take the assembly which was compiled on the Windows operating system and try to run it on Linux or another operating system then it will give you an error because that code is native to only Windows operating system. That's why it is called Native code or Object code. This is the problem with the pre-DotNet application, they are not portable and we have to build different operating systems.

Now let's understand how a DotNet application executes. DotNet supports several programming languages like C#, VB, C++, etc. When you build a DotNet application using any of these languages and compile using the respective language compiler, we get an assembly here also but unlike pre-DotNet application, it does not contain native code, instead, it contains intermediate language. This is the main difference between a DotNet program and a Pre-DotNet program but your operating system cannot understand the intermediate language so we need a runtime environment name as CLR (Common Language Runtime) to convert the intermediate language to native code. 

Now the question is how does this CLR come in between to do this job? When we install DotNet on our system, we basically install two important components one is the DotNet framework class library and another one is CLR. This is like a heart for DotNet program execution. This CLR layer exists between Assembly and the Operating system. Within CLR there is a very important component named as JIT compiler which takes IL (Intermediate Language) as input and generates native code as the output for the Operating system. 

So the biggest advantage of the DotNet application is that is portable which means that the same code can run on any operating system with the help of CLR installed on that operating system. Another advantage of DotNet is that the runtime environment contains a garbage collector which will clean the object or memory that is not in use programmer doesn't have to worry much about memory management.

Note: The native code is not stored permanently anywhere after we close the program the native code is thrown away and when we execute the program again the native code will generate again. (alert-success)