System.Version class

Article
01/08/2024

This article provides supplementary remarks to the reference documentation for this API.

The Version class represents the version number of an assembly, operating system, or the common language runtime. Version numbers consist of two to four components: major, minor, build, and revision. The major and minor components are required; the build and revision components are optional, but the build component is required if the revision component is defined. All defined components must be integers greater than or equal to 0. The format of the version number is as follows (optional components are shown in square brackets):

major.minor[.build[.revision]]

The components are used by convention as follows:

Major: Assemblies with the same name but different major versions are not interchangeable. A higher version number might indicate a major rewrite of a product where backward compatibility cannot be assumed.
Minor: If the name and major version number on two assemblies are the same, but the minor version number is different, this indicates significant enhancement with the intention of backward compatibility. This higher minor version number might indicate a point release of a product or a fully backward-compatible new version of a product.
Build: A difference in build number represents a recompilation of the same source. Different build numbers might be used when the processor, platform, or compiler changes.
Revision: Assemblies with the same name, major, and minor version numbers but different revisions are intended to be fully interchangeable. A higher revision number might be used in a build that fixes a security hole in a previously released assembly.

Subsequent versions of an assembly that differ only by build or revision numbers are considered to be Hotfix updates of the prior version.

Important

The value of Version properties that have not been explicitly assigned a value is undefined (-1).

The MajorRevision and MinorRevision properties enable you to identify a temporary version of your application that, for example, corrects a problem until you can release a permanent solution. Furthermore, the Windows NT operating system uses the MajorRevision property to encode the service pack number.

Assign version information to assemblies

Ordinarily, the Version class is not used to assign a version number to an assembly. Instead, the AssemblyVersionAttribute class is used to define an assembly's version, as illustrated by the example in this article.

Retrieve version information

Version objects are most frequently used to store version information about some system or application component (such as the operating system), the common language runtime, the current application's executable, or a particular assembly. The following examples illustrate some of the most common scenarios:

Retrieving the operating system version. The following example uses the OperatingSystem.Version property to retrieve the version number of the operating system.

// Get the operating system version.
OperatingSystem os = Environment.OSVersion;
Version ver = os.Version;
Console.WriteLine("Operating System: {0} ({1})", os.VersionString, ver.ToString());

// Get the operating system version.
let os = Environment.OSVersion
let ver = os.Version
printfn $"Operating System: {os.VersionString} ({ver})"

' Get the operating system version.
Dim os As OperatingSystem = Environment.OSVersion
Dim ver As Version = os.Version
Console.WriteLine("Operating System: {0} ({1})", os.VersionString, ver.ToString())

Retrieving the version of the common language runtime. The following example uses the Environment.Version property to retrieve version information about the common language runtime.

// Get the common language runtime version.
Version ver = Environment.Version;
Console.WriteLine("CLR Version {0}", ver.ToString());

// Get the common language runtime version.
let ver = Environment.Version
printfn $"CLR Version {ver}"

' Get the common language runtime version.
Dim ver As Version = Environment.Version
Console.WriteLine("CLR Version {0}", ver.ToString())

Retrieving the current application's assembly version. The following example uses the Assembly.GetEntryAssembly method to obtain a reference to an Assembly object that represents the application executable and then retrieves its assembly version number.

using System;
using System.Reflection;

public class Example4
{
   public static void Main()
   {
      // Get the version of the executing assembly (that is, this assembly).
      Assembly assem = Assembly.GetEntryAssembly();
      AssemblyName assemName = assem.GetName();
      Version ver = assemName.Version;
      Console.WriteLine("Application {0}, Version {1}", assemName.Name, ver.ToString());
   }
}

open System.Reflection

// Get the version of the executing assembly (that is, this assembly).
let assem = Assembly.GetEntryAssembly()
let assemName = assem.GetName()
let ver = assemName.Version
printfn $"Application {assemName.Name}, Version {ver}"

Imports System.Reflection

Module Example3
    Public Sub Main()
        ' Get the version of the executing assembly (that is, this assembly).
        Dim assem As Assembly = Assembly.GetEntryAssembly()
        Dim assemName As AssemblyName = assem.GetName()
        Dim ver As Version = assemName.Version
        Console.WriteLine("Application {0}, Version {1}", assemName.Name, ver.ToString())
    End Sub
End Module

Retrieving the current assembly's assembly version. The following example uses the Type.Assembly property to obtain a reference to an Assembly object that represents the assembly that contains the application entry point, and then retrieves its version information.

using System;
using System.Reflection;

public class Example3
{
   public static void Main()
   {
      // Get the version of the current assembly.
      Assembly assem = typeof(Example).Assembly;
      AssemblyName assemName = assem.GetName();
      Version ver = assemName.Version;
      Console.WriteLine("{0}, Version {1}", assemName.Name, ver.ToString());
   }
}

type Example = class end

// Get the version of the current assembly.
let assem = typeof<Example>.Assembly
let assemName = assem.GetName()
let ver = assemName.Version
printfn $"{assemName.Name}, Version {ver}"

Imports System.Reflection

Module Example1
    Public Sub Main()
        ' Get the version of the current assembly.
        Dim assem As Assembly = GetType(Example).Assembly
        Dim assemName As AssemblyName = assem.GetName()
        Dim ver As Version = assemName.Version
        Console.WriteLine("{0}, Version {1}", assemName.Name, ver.ToString())
    End Sub
End Module

Retrieving the version of a specific assembly. The following example uses the Assembly.ReflectionOnlyLoadFrom method to obtain a reference to an Assembly object that has a particular file name, and then retrieves its version information. Note that several other methods also exist to instantiate an Assembly object by file name or by strong name.

using System;
using System.Reflection;

public class Example5
{
   public static void Main()
   {
      // Get the version of a specific assembly.
      string filename = @".\StringLibrary.dll";
      Assembly assem = Assembly.ReflectionOnlyLoadFrom(filename);
      AssemblyName assemName = assem.GetName();
      Version ver = assemName.Version;
      Console.WriteLine("{0}, Version {1}", assemName.Name, ver.ToString());
   }
}

open System.Reflection

// Get the version of a specific assembly.
let filename = @".\StringLibrary.dll"
let assem = Assembly.ReflectionOnlyLoadFrom filename
let assemName = assem.GetName()
let ver = assemName.Version
printfn $"{assemName.Name}, Version {ver}"

Imports System.Reflection

Module Example4
    Public Sub Main()
        ' Get the version of a specific assembly.
        Dim filename As String = ".\StringLibrary.dll"
        Dim assem As Assembly = Assembly.ReflectionOnlyLoadFrom(filename)
        Dim assemName As AssemblyName = assem.GetName()
        Dim ver As Version = assemName.Version
        Console.WriteLine("{0}, Version {1}", assemName.Name, ver.ToString())
    End Sub
End Module

Retrieving the Publish Version of a ClickOnce application. The following example uses the ApplicationDeployment.CurrentVersion property to display an application's Publish Version. Note that its successful execution requires the example's application identity to be set. This is handled automatically by the Visual Studio Publish Wizard.

using System;
using System.Deployment.Application;

public class Example
{
   public static void Main()
   {
      Version ver = ApplicationDeployment.CurrentDeployment.CurrentVersion;
      Console.WriteLine("ClickOnce Publish Version: {0}", ver);
   }
}

Imports System.Deployment.Application

Module Example0
    Public Sub Main()
        Dim ver As Version = ApplicationDeployment.CurrentDeployment.CurrentVersion
        Console.WriteLine("ClickOnce Publish Version: {0}", ver)
    End Sub
End Module

Important

The Publish Version of an application for ClickOnce deployment is completely independent of its assembly version.

Compare version objects

You can use the CompareTo method to determine whether one Version object is earlier than, the same as, or later than a second Version object. The following example indicates that Version 2.1 is later than Version 2.0.

Version v1 = new Version(2, 0);
Version v2 = new Version("2.1");
Console.Write("Version {0} is ", v1);
switch(v1.CompareTo(v2))
{
   case 0:
      Console.Write("the same as");
      break;
   case 1:
      Console.Write("later than");
      break;
   case -1:
      Console.Write("earlier than");
      break;
}
Console.WriteLine(" Version {0}.", v2);                  
// The example displays the following output:
//       Version 2.0 is earlier than Version 2.1.

open System

let v1 = Version(2, 0)
let v2 = Version "2.1"

printf $"Version {v1} is "

match v1.CompareTo v2 with
| 0 -> printf "the same as"
| 1 -> printf "later than"
| _ -> printf "earlier than"

printf $" Version {v2}."
// The example displays the following output:
//       Version 2.0 is earlier than Version 2.1.

Dim v1 As New Version(2,0)
Dim v2 As New Version("2.1")
Console.Write("Version {0} is ", v1)
Select Case v1.CompareTo(v2)
   Case 0
      Console.Write("the same as")
   Case 1
      Console.Write("later than")
   Case -1
      Console.Write("earlier than")
End Select
Console.WriteLine(" Version {0}.", v2)                  
' The example displays the following output:
'       Version 2.0 is earlier than Version 2.1.

For two versions to be equal, the major, minor, build, and revision numbers of the first Version object must be identical to those of the second Version object. If the build or revision number of a Version object is undefined, that Version object is considered to be earlier than a Version object whose build or revision number is equal to zero. The following example illustrates this by comparing three Version objects that have undefined version components.

using System;

enum VersionTime {Earlier = -1, Same = 0, Later = 1 };

public class Example2
{
   public static void Main()
   {
      Version v1 = new Version(1, 1);
      Version v1a = new Version("1.1.0");
      ShowRelationship(v1, v1a);
      
      Version v1b = new Version(1, 1, 0, 0);
      ShowRelationship(v1b, v1a);
   }

   private static void ShowRelationship(Version v1, Version v2)
   {
      Console.WriteLine("Relationship of {0} to {1}: {2}", 
                        v1, v2, (VersionTime) v1.CompareTo(v2));       
   }
}
// The example displays the following output:
//       Relationship of 1.1 to 1.1.0: Earlier
//       Relationship of 1.1.0.0 to 1.1.0: Later

open System

type VersionTime =
    | Earlier = -1
    | Same = 0
    | Later = 1

let showRelationship (v1: Version) (v2: Version) =
    printfn $"Relationship of {v1} to {v2}: {v1.CompareTo v2 |> enum<VersionTime>}" 

let v1 = Version(1, 1)
let v1a = Version "1.1.0"
showRelationship v1 v1a

let v1b = Version(1, 1, 0, 0)
showRelationship v1b v1a

// The example displays the following output:
//       Relationship of 1.1 to 1.1.0: Earlier
//       Relationship of 1.1.0.0 to 1.1.0: Later

Public Enum VersionTime
   Earlier = -1
   Same = 0
   Later = 1
End Enum

Module Example2
    Public Sub Main()
        Dim v1 As New Version(1, 1)
        Dim v1a As New Version("1.1.0")
        ShowRelationship(v1, v1a)

        Dim v1b As New Version(1, 1, 0, 0)
        ShowRelationship(v1b, v1a)
    End Sub

    Private Sub ShowRelationship(v1 As Version, v2 As Version)
        Console.WriteLine("Relationship of {0} to {1}: {2}",
                        v1, v2, CType(v1.CompareTo(v2), VersionTime))
    End Sub
End Module
' The example displays the following output:
'       Relationship of 1.1 to 1.1.0: Earlier
'       Relationship of 1.1.0.0 to 1.1.0: Later

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System.Version class

Assign version information to assemblies

Retrieve version information

Compare version objects

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