AssemblyVersionAttribute Class
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AssemblyVersionAttribute Class


Specifies the version of the assembly being attributed.

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


[AttributeUsageAttribute(AttributeTargets.Assembly, Inherited = false)]
public sealed class AssemblyVersionAttribute : Attribute


Initializes a new instance of the AssemblyVersionAttribute class with the version number of the assembly being attributed.


When implemented in a derived class, gets a unique identifier for this Attribute.(Inherited from Attribute.)


Gets the version number of the attributed assembly.


This API supports the product infrastructure and is not intended to be used directly from your code. Returns a value that indicates whether this instance is equal to a specified object.(Inherited from Attribute.)


Returns the hash code for this instance.(Inherited from Attribute.)


Gets the Type of the current instance.(Inherited from Object.)


When overridden in a derived class, indicates whether the value of this instance is the default value for the derived class.(Inherited from Attribute.)


When overridden in a derived class, returns a value that indicates whether this instance equals a specified object.(Inherited from Attribute.)


Returns a string that represents the current object.(Inherited from Object.)

System_CAPS_pubinterfaceSystem_CAPS_privmethod_Attribute.GetIDsOfNames(Guid, IntPtr, UInt32, UInt32, IntPtr)

Maps a set of names to a corresponding set of dispatch identifiers.(Inherited from Attribute.)

System_CAPS_pubinterfaceSystem_CAPS_privmethod_Attribute.GetTypeInfo(UInt32, UInt32, IntPtr)

Retrieves the type information for an object, which can be used to get the type information for an interface.(Inherited from Attribute.)


Retrieves the number of type information interfaces that an object provides (either 0 or 1).(Inherited from Attribute.)

System_CAPS_pubinterfaceSystem_CAPS_privmethod_Attribute.Invoke(UInt32, Guid, UInt32, Int16, IntPtr, IntPtr, IntPtr, IntPtr)

Provides access to properties and methods exposed by an object.(Inherited from Attribute.)

The AssemblyVersionAttribute attribute is used to assign a version number to an assembly. That version number is then stored with the assembly's metadata.

The assembly version number is part of an assembly's identity and plays a key part in binding to the assembly and in version policy. The default version policy for the runtime is that applications run only with the versions they were built and tested with, unless overridden by explicit version policy in configuration files (the application configuration file, the publisher policy file, and the computer's administrator configuration file). See Assemblies in the Common Language Runtime for more information.


Version checking only occurs with strong-named assemblies.

The version number has four parts, as follows:

<major version>.<minor version>.<build number>.<revision>


All components of the version must be integers greater than or equal to 0. Metadata restricts the major, minor, build, and revision components for an assembly to a maximum value of UInt16.MaxValue - 1. If a component exceeds this value, a compilation error occurs.

You can specify all the values or you can accept the default build number, revision number, or both by using an asterisk (*). For example, [assembly:AssemblyVersion("")] indicates 2 as the major version, 3 as the minor version, 25 as the build number, and 1 as the revision number. A version number such as [assembly:AssemblyVersion("1.2.*")] specifies 1 as the major version, 2 as the minor version, and accepts the default build and revision numbers. A version number such as [assembly:AssemblyVersion("1.2.15.*")] specifies 1 as the major version, 2 as the minor version, 15 as the build number, and accepts the default revision number. The default build number increments daily. The default revision number is the number of seconds since midnight local time (without taking into account time zone adjustments for daylight saving time), divided by 2.


If you specify an asterisk for the build number, you cannot specify a revision number.

The assembly major and minor versions are used as the type library version number when the assembly is exported. Some COM hosts do not accept type libraries with the version number 0.0. Therefore, if you want to expose an assembly to COM clients, set the assembly version explicitly to 1.0 in the AssemblyVersionAttribute page for projects created outside Visual Studio 2005 and with no AssemblyVersionAttribute specified. Do this even when the assembly version is 0.0. All projects created in Visual Studio 2005 have a default assembly version of 1.0.*.

To get the name of an assembly you have loaded, call GetName on the assembly to get an AssemblyName, and then get the Version property. To get the name of an assembly you have not loaded, call GetAssemblyName from your client application to check the assembly version that your application uses.

The AssemblyVersionAttribute attribute can only be applied once. Some Visual Studio project templates already include the attribute. In those projects, adding the attribute in code causes a compiler error.

The following example uses the AssemblyVersionAttribute attribute to assign a version number to an assembly. At compile time, this version information is stored with the assembly's metadata. At run time, the example retrieves the value of the Type.Assembly property on a type found in the assembly to get a reference to the executing assembly, and it retrieves the assembly's version information from the Version property of the AssemblyName object returned by the Assembly.GetName method.

using System;
using System.Reflection;


public class Example1
   public static void Main()
      Assembly thisAssem = typeof(Example1).Assembly;
      AssemblyName thisAssemName = thisAssem.GetName();

      Version ver = thisAssemName.Version;

      Console.WriteLine("This is version {0} of {1}.", ver, thisAssemName.Name);    
// The example displays the following output:
//        This is version of Example1.

Universal Windows Platform
Available since 4.5
.NET Framework
Available since 1.1
Portable Class Library
Supported in: portable .NET platforms
Available since 2.0
Windows Phone Silverlight
Available since 7.0
Windows Phone
Available since 8.1

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

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