How to programmatically generate C# files from a DLL or EXE

I’m working on a project that involves researching and comparing many versions of the same DLL. I don’t have the source for every version of this DLL so I needed a way to convert it to C# files and diff those. Since there are thousands of versions of this file out there I needed to be able to generate the C# files programmatically.
I started with Reflector, but it doesn’t have a simple API needed to generate the files programmatically.
I came across [JustDecompile](http://www.telerik.com/products/decompiler.aspx\. from Telerik and found that they do have a command line API that works great. I could have just invoked the EXE with Process.Start, but I figured I should see how they are doing and see if I could do everything inproc. So I decompiled the JustDecompile.exe file and found a very simple DLL method that they use to output C# files.

1. Download JustDecompile
2. Open up your project and Add References to these two DLLs.

C:\Program Files (x86)\Telerik\JustDecompile\Libraries\JustDecompile.Tools.MSBuildProjectBuilder.dll
C:\Program Files (x86)\Telerik\JustDecompile\Libraries\JustDecompiler.dll

3. Add the following namespaces:

using JustDecompile.Tools.MSBuildProjectBuilder;
using Telerik.JustDecompiler.Languages.CSharp;
using System.Threading;

4. Add this code to your project where you want to programmatically decompile code

MSBuildProjectBuilder projectBuilder = new MSBuildProjectBuilder([path to dll], outfolder, new CSharpV4());
projectBuilder.ProjectFileCreated += new EventHandler<ProjectFileCreatedEvent>(projectBuilder_ProjectFileCreated);</ProjectFileCreatedEvent>
projectBuilder.BuildProject(new CancellationToken());

Where [path to dll] is the path to the dll that you want to decompile and outfolder is the folder you want to output the C# files.

5. Add this event handler to be notified when the Visual Studio Project file has been created

static void projectBuilder_ProjectFileCreated(object sender, ProjectFileCreatedEvent e)
{
//throw new NotImplementedException();
}

Hope this saves you some time.

Jon