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AssemblyBuilder.DefineUnmanagedResource Method (Byte[])

Defines an unmanaged resource for this assembly as an opaque blob of bytes.

Namespace:  System.Reflection.Emit
Assembly:  mscorlib (in mscorlib.dll)

public void DefineUnmanagedResource(
	byte[] resource


Type: System.Byte[]
The opaque blob of bytes representing the unmanaged resource.


An unmanaged resource was previously defined.


resource is null.


The caller does not have the required permission.

An assembly can be associated with only one unmanaged resource. This means that calling DefineVersionInfoResource or DefineUnmanagedResource after either one of the methods was called previously will throw the System.ArgumentException being throw. Multiple unmanaged resources need to be merged with a tool such as the Microsoft ResMerge utility (not supplied with the common language runtime).

The following code sample creates and attaches an array of bytes representing an unmanaged resource to a dynamic assembly, using DefineUnmanagedResource.

using System;
using System.Threading;
using System.Reflection;
using System.Reflection.Emit;
using System.Resources;

public class MyAssemblyResource
   internal static void Main()
      AssemblyBuilder myAssembly = CreateAssembly("MyEmitTestAssembly");

      // Defines a standalone managed resource for this assembly.
      IResourceWriter myResourceWriter = myAssembly.DefineResource("myResourceFile",
         "A sample Resource File", "MyAssemblyResource.resources", 

      myResourceWriter.AddResource("AddResource Test", "Testing for the added resource");

      myAssembly.Save(myAssembly.GetName().Name + ".dll");

      // Defines an unmanaged resource file for this assembly.
      myAssembly.DefineUnmanagedResource(new byte[]{01, 00, 01});

   private static AssemblyBuilder CreateAssembly(string name)
      AssemblyName aName = new AssemblyName(name);
      AssemblyBuilder myAssembly = 

      // Define a dynamic module.
      ModuleBuilder myModule = 
         myAssembly.DefineDynamicModule(aName.Name, aName.Name + ".dll");

      // Define a public class named "EmitClass" in the assembly.
      TypeBuilder myEmitClass = myModule.DefineType("EmitClass", TypeAttributes.Public);

      // Define the Display method.
      MethodBuilder myMethod = myEmitClass.DefineMethod("Display",
         MethodAttributes.Public, typeof(String), null);

      // Generate IL for Display method.
      ILGenerator methodIL = myMethod.GetILGenerator();
      methodIL.Emit(OpCodes.Ldstr, "Display method gets called.");



.NET Framework

Supported in: 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.