Brendan Enrick

Daily Software Development

Viewing Disassembled IL with ILDASM

For those of you who are simply computer geeks I present to you an easy way to view the generated intermediate language code that is generated when you’re using the .NET Framework. So if you’ve ever wanted to see what is generated from your compiler, so you can see what code gets executed at run-time you just need to take a few simple steps.

Open up the Visual Studio Command Prompt. You can find this command prompt in the Start Menu inside of the tools folder for Visual Studio.

VS-Command-Prompt

From here you will be able to open up ILDASM’s graphical user interface. Open it by typing “ILDASM”. It’s a very simple program.

ILDASM-Start

From here you will want to open up the assembled file you want to view. This could be a class library or an executable. In this example I will use a “Hello World” console application.

ILDASM-Project-Open

The console application really only has one class. ILDASM_World.Program, which can be seen in the image. You can see the ILDASM_World namespace is where the class is located. Inside of the class we have a constructor (this is the default one I did not write the code for it). See this is neat, because we can see that a default constructor was created for us and we can see exactly what it does.

The Main method listed there is a standard one with a Console.Writeline(“Hello World!”); line written in it.

When we open up the method to view it we see the following IL is generated when we compile.

ILDASM-Main

Now what is really cool here is that I bet pretty much every person reading this can figure out exactly what that code is doing. I think that people could have figured it out without my having to explain it. It is really cool to see. There are a lot of awesome tricks you can see here. Also if you’re ever wondering what is going to happen when you compile something I recommend looking here. You’ll be able to see exactly what actually happens.

This will assist you when you’re writing your code since you’ll be able to make a more educated decision on which approach to take with your code if you see what will be generated behind the scenes.

Your homework is to try this with loops and with a goto.

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