Assembly Class

Represents an assembly, which is a reusable, versionable, and self-describing building block of a common language runtime application.

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

public class Assembly : _Assembly, IEvidenceFactory, ICustomAttributeProvider, 
/** @attribute SerializableAttribute() */ 
/** @attribute ClassInterfaceAttribute(ClassInterfaceType.None) */ 
/** @attribute ComVisibleAttribute(true) */ 
public class Assembly implements _Assembly, IEvidenceFactory, 
	ICustomAttributeProvider, ISerializable
public class Assembly implements _Assembly, IEvidenceFactory, 
	ICustomAttributeProvider, ISerializable
Not applicable.

Use the Assembly class to load assemblies, to explore the metadata and constituent parts of assemblies, to discover the types contained in assemblies, and to create instances of those types.

To get an array of Assembly objects representing the assemblies currently loaded into an application domain (for example, the default application domain of a simple project), use the AppDomain.GetAssemblies method.

To load assemblies dynamically, the Assembly class provides the following static methods (Shared methods in Visual Basic). Assemblies are loaded into the application domain where the load operation occurs.

  • The recommended way to load assemblies is to use the Load method, which identifies the assembly to be loaded by its display name (for example, "System.Windows.Forms, Version=, Culture=neutral, PublicKeyToken=b77a5c561934e089"). The search for the assembly follows the rules described in How the Runtime Locates Assemblies.

  • The ReflectionOnlyLoad and ReflectionOnlyLoadFrom methods enable you to load an assembly for reflection, but not for execution. For example, an assembly that targets a 64-bit platform can be examined by code that is running on a 32-bit platform.

  • The LoadFile and LoadFrom methods are provided for rare scenarios in which an assembly must be identified by path.

To get an Assembly object for the currently executing assembly, use the GetExecutingAssembly method.

Many members of the Assembly class provide information about an assembly. For example:

  • The GetName method returns an AssemblyName object that provides access to the parts of the assembly display name.

  • The GetCustomAttributes method lists the attributes applied to the assembly.

  • The GetFiles method provides access to the files in the assembly manifest.

  • The GetManifestResourceNames method provides the names of the resources in the assembly manifest.

The GetTypes method lists all the types in the assembly. The GetExportedTypes method lists the types that are visible to callers outside the assembly. The GetType method can be used to search for a particular type in the assembly. The CreateInstance method can be used to search for and create instances of types in the assembly.

For more information on assemblies, see Application Domains and Assemblies.

The following code example shows how to obtain the currently executing assembly, create an instance of a type contained in that assembly, and invoke one of the type's methods with late binding. For this purpose, the code example defines a class named Example, with a method named SampleMethod. The constructor of the class accepts an integer, which is used to compute the return value of the method.

The code example also demonstrates the use of the GetName method to obtain an AssemblyName object that can be used to parse the full name of the assembly. The example displays the version number of the assembly, the CodeBase property, and the EntryPoint property.

using System;
using System.Reflection;
using System.Security.Permissions;


public class Example
    private int factor;
    public Example(int f)
        factor = f;

    public int SampleMethod(int x) 
        Console.WriteLine("\nExample.SampleMethod({0}) executes.", x);
        return x * factor;

    public static void Main()
        Assembly assem = Assembly.GetExecutingAssembly();

        Console.WriteLine("Assembly Full Name:");

        // The AssemblyName type can be used to parse the full name.
        AssemblyName assemName = assem.GetName();
        Console.WriteLine("\nName: {0}", assemName.Name);
        Console.WriteLine("Version: {0}.{1}", 
            assemName.Version.Major, assemName.Version.Minor);

        Console.WriteLine("\nAssembly CodeBase:");

        // Create an object from the assembly, passing in the correct number
        // and type of arguments for the constructor.
        Object o = assem.CreateInstance("Example", false, 
            null, new Object[] { 2 }, null, null);

        // Make a late-bound call to an instance method of the object.    
        MethodInfo m = assem.GetType("Example").GetMethod("SampleMethod");
        Object ret = m.Invoke(o, new Object[] { 42 });
        Console.WriteLine("SampleMethod returned {0}.", ret);

        Console.WriteLine("\nAssembly entry point:");

/* This code example produces output similar to the following:

Assembly Full Name:
source, Version=1.0.2000.0, Culture=neutral, PublicKeyToken=null

Name: source
Version: 1.0

Assembly CodeBase:

Example.SampleMethod(42) executes.
SampleMethod returned 84.

Assembly entry point:
Void Main()

This type is thread safe.

Windows 98, Windows Server 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.

.NET Framework

Supported in: 3.0, 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 2.0, 1.0

XNA Framework

Supported in: 1.0