如何查看安裝的 .NET Framework 版本為何和是否有做update

可以參考MSDN的資料：

How to: Determine Which .NET Framework Versions Are Installed

http://msdn.microsoft.com/en-us/library/hh925568(v=vs.110).aspx

Users can install and run multiple versions of the .NET Framework on their computers. When you develop or deploy your app, you might need to know which .NET Framework versions are installed on the user’s computer. Note that the .NET Framework consists of two main components, which are versioned separately:

• A set of assemblies, which are collections of types and resources that provide the functionality for your apps. The .NET Framework and assemblies share the same version number.
• The common language runtime (CLR), which manages and executes your app's code. The CLR is identified by its own version number (see .NET Framework Versions and Dependencies).

To get an accurate list of the .NET Framework versions installed on a computer, you can view the registry or query the registry in code:

      Viewing the registry (versions 1-4)
      Viewing the registry (version 4.5 and later)
      Using code to query the registry (versions 1-4)
      Using code to query the registry (version 4.5 and later)

To find the CLR version, you can use a tool or code:

      Using the Clrver tool
      Using code to query the System.Environment class

For information about detecting the installed updates for each version of the .NET Framework, see How to: Determine Which .NET Framework Updates Are Installed. For information about installing the .NET Framework, see the installation guide.

To find .NET Framework versions by viewing the registry (.NET Framework 1-4)

1. On the Start menu, choose Run.
2. In the Open box, enter regedit.exe.
   You must have administrative credentials to run regedit.exe.
3. In the Registry Editor, open the following subkey:
   HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\NET Framework Setup\NDP
   The installed versions are listed under the NDP subkey. The version number is stored in the Version entry. For the .NET Framework 4 the Version entry is under the Client or Full subkey (under NDP), or under both subkeys.

   Note
   The "NET Framework Setup" folder in the registry does not begin with a period.

To find .NET Framework versions by viewing the registry (.NET Framework 4.5 and later)

1. On the Start menu, choose Run.
2. In the Open box, enter regedit.exe.
   You must have administrative credentials to run regedit.exe.
3. In the Registry Editor, open the following subkey:
   HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\NET Framework Setup\NDP\v4\Full
   Check for a DWORD value named Release. The existence of the Release DWORD indicates that the .NET Framework 4.5 or newer has been installed on that computer.
   
   The value of the Release DWORD indicates which version of the .NET Framework is installed.

   Value of the Release DWORD	Version
   378389	.NET Framework 4.5
   378675	.NET Framework 4.5.1 installed with Windows 8.1
   378758	.NET Framework 4.5.1 installed on Windows 8, Windows 7 SP1, or Windows Vista SP2
   379893	.NET Framework 4.5.2

To find .NET Framework versions by querying the registry in code (.NET Framework 1-4)

• Use the Microsoft.Win32::RegistryKey class to access the Software\Microsoft\NET Framework Setup\NDP\ subkey under HKEY_LOCAL_MACHINE in the Windows registry.
  The following code shows an example of this query.

  Note
  This code does not show how to detect .NET Framework 4.5 or later. Check the Release DWORD to detect those versions, as described in the previous section.

  C#

  VB

  C++

  No code example is currently available or this language may not be supported.
  The example produces output that's similar to the following:
  v2.0.50727  2.0.50727.4016  SP2
  v3.0  3.0.30729.4037  SP2
  v3.5  3.5.30729.01  SP1
  v4
    Client  4.0.30319
    Full  4.0.30319
  

To find .NET Framework versions by querying the registry in code (.NET Framework 4.5 and later)

1. The existence of the Release DWORD indicates that the .NET Framework 4.5 or later has been installed on a computer. The value of the keyword indicates the installed version. To check this keyword, use the OpenBaseKey and OpenSubKey methods of the Microsoft.Win32::RegistryKey class to access the Software\Microsoft\NET Framework Setup\NDP\v4.0\Full subkey under HKEY_LOCAL_MACHINE in the Windows registry.
2. Check the value of the Release keyword to determine the installed version. Here are the .NET Framework versions and associated Release keywords.

   Version	Value of the Release DWORD
   .NET Framework 4.5	378389
   .NET Framework 4.5.1 installed with Windows 8.1	378675
   .NET Framework 4.5.1 installed on Windows 8, Windows 7 SP1, or Windows Vista SP2	378758
   .NET Framework 4.5.2	379893

   Here's an example of this query:
   C#

   VB

   C++

   No code example is currently available or this language may not be supported.
   The example produces output that's similar to the following:
   The .NET Framework version 4.5.1 is installed
   

To find the current runtime version by using the Clrver tool

• Use the CLR Version Tool (Clrver.exe) to determine which versions of the common language runtime are installed on a computer.
  From a Visual Studio Command Prompt, enter clrver. This command produces output similar to the following:
  Versions installed on the machine:
  v2.0.50727
  v4.0.30319
  

  For more information about using this tool, see Clrver.exe (CLR Version Tool).

To find the current runtime version by querying the Environment class in code

• Query the Version property of the Environment class to identify the version of the runtime that is currently executing the code. You can use the Version::Majorproperty to get the major release identifier (for example, "4" for version 4.0), the Version::Minor property to get the minor release identifier (for example, "0" for version 4.0), or the Object::ToString method to get the entire version string (for example, "4.0.30319.18010", as shown in the following code). This property returns a single value that reflects the version of the runtime that is currently executing the code; it does not return assembly versions or other versions of the runtime that may have been installed on the computer.
  Here's an example of querying the Environment::Version property for runtime version information:
  C#

  VB

  C++

  No code example is currently available or this language may not be supported.
  The example produces output that's similar to the following:
  Version: 4.0.30319.18010

How to: Determine Which .NET Framework Updates Are Installed

http://msdn.microsoft.com/en-us/library/hh925567(v=vs.110).aspx

The installed updates for each version of the .NET Framework installed on a computer are listed in the Windows registry. You can use the Registry Editor (regedit.exe) to view this information.

In the Registry Editor, the .NET Framework versions and installed updates for each version are stored in different subkeys. For information about detecting the installed version numbers, see How to: Determine Which .NET Framework Versions Are Installed. For information about installing the .NET Framework, see theinstallation guide.

To find installed updates

1. On the Start menu, choose Run.
2. In the Open box, enter regedit.exe.
   You must have administrative credentials to run regedit.exe.
3. In the Registry Editor, open the following subkey:
   HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\Updates
   The installed updates are listed under subkeys that identify the .NET Framework version they apply to. Each update is identified by a Knowledge Base (KB) number.

Example

The following code programmatically determines the .NET Framework updates that are installed on a computer. You must have administrative credentials to run this example.

C#

VB

C++

No code example is currently available or this language may not be supported.

The example produces output that's similar to the following:

Microsoft .NET Framework 3.5 SP1
  KB953595  Hotfix for Microsoft .NET Framework 3.5 SP1 (KB953595)
  SP1
    KB2657424  Security Update for Microsoft .NET Framework 3.5 SP1 (KB2657424)
    KB958484  Hotfix for Microsoft .NET Framework 3.5 SP1 (KB958484)
    KB963707  Update for Microsoft .NET Framework 3.5 SP1 (KB963707)
Microsoft .NET Framework 4 Client Profile
  KB2160841  Security Update for Microsoft .NET Framework 4 Client Profile (KB2160841)
  KB2446708  Security Update for Microsoft .NET Framework 4 Client Profile (KB2446708)
  KB2468871  Update for Microsoft .NET Framework 4 Client Profile (KB2468871)
  KB2478663  Security Update for Microsoft .NET Framework 4 Client Profile (KB2478663)
  KB2518870  Security Update for Microsoft .NET Framework 4 Client Profile (KB2518870)
  KB2533523  Update for Microsoft .NET Framework 4 Client Profile (KB2533523)
  KB2539636  Security Update for Microsoft .NET Framework 4 Client Profile (KB2539636)
  KB2572078  Security Update for Microsoft .NET Framework 4 Client Profile (KB2572078)
  KB2633870  Security Update for Microsoft .NET Framework 4 Client Profile (KB2633870)
  KB2656351  Security Update for Microsoft .NET Framework 4 Client Profile (KB2656351)
Microsoft .NET Framework 4 Extended
  KB2416472  Security Update for Microsoft .NET Framework 4 Extended (KB2416472)
  KB2468871  Update for Microsoft .NET Framework 4 Extended (KB2468871)
  KB2487367  Security Update for Microsoft .NET Framework 4 Extended (KB2487367)
  KB2533523  Update for Microsoft .NET Framework 4 Extended (KB2533523)
  KB2656351  Security Update for Microsoft .NET Framework 4 Extended (KB2656351)