You can get more information about the ILMerge utility from here and you can download it from here.

In this post I am writing about embedding a .Net DLL in to an executable using ILMerge.

Here is the code for the executable

using System;
public class MainClass
{
	static void Main(string[] args)
	{
		Helper.WriteMessage("Hello World");
	}
}

Here is the code for the library. I am using a static function from the library and using it.

using System;
public static class Helper
{
	public static void WriteMessage(string message)
	{
		Console.WriteLine(message);
	}
}

I compiled the library first using this command

csc /t:library helper.cs

Then the executable using

csc /r:helper.dll main.cs

Now I try to deploy the main.exe (which is the output file) without the helper.dll it will throw some error like this

Unhandled Exception: System.IO.FileNotFoundException: Could not load file or ass
embly ‘helper, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null’ or one of
its dependencies. The system cannot find the file specified.

Now I am merging these to assemblies using ILMerge using

“c:\Program Files\Microsoft\ILMerge\ILMerge.exe” main.exe helper.dll /out:Sample.exe /t:exe

It will generate an executable with filename as Sample.exe, and which can be deployed without helper.dll and will work fine. This is the ILDasm screenshots of two.

IL before merging

IL after merging

Happy Coding.

Generate IL code using ILDASM.exe

1. First create a HelloWorld.cs and compile it to HelloWorld.exe

using System;

public class HelloWorld
{
static int Main(string[] args)
	{
Console.WriteLine("Hello World");
		return(0);
	}
}

2. Use csc.exeto compile the cs file to exe. – csc HelloWorld.cs
3. Use ildasm.exe HelloWorld.Exe to view the IL Code. You can find ILDASM in the Microsoft .Net SDK Path
   

   ILDASM - Exploring HelloWorld.exe

4. To generate the IL code use Select Dump option from File Menu or Press Ctrl+D. It will asks for a location to save the IL code.
   

   IL Code Generated

5. Use any Editor to modify the IL code. You can find all the string values ( “Hello World” in this example ) as it is in the IL code. Modify it.( I am modifying it as “Hello World from IL Code”).
   

   IL Code - Notepad

So we created the IL code and modified.
Generate Assembly from IL code using ILASM.exe

1. Invoke the ILASM.exe with IL file as the parameter. ilasm helloworld_il.il
2. It will show some details about assembling the IL code to assembly. And if the operation is successful you will get an exe in the location with HelloWorld_IL.exe.
   

   Assembling the IL code to EXE

3. If you invoke the exe from command prompt it will display the modified string instead of Hello World.(In this example “Hello World from IL Code”).

You can do more if you know how IL works. Happy IL Programming