问题
I've installed Windows 8, Visual Studio 2012 but don't have a v4.5 directory in %WINDIR%\Microsoft.NET\Framework.
Have I done something wrong, or is .NET 4.5 different from others?
If it's because I have not installed the tools, is there a set of different tools to download? As far as I can tell, I am able to build .NET 4.5 apps OK.
回答1:
.NET 4.5 is an in place replacement for 4.0 - you will find the assemblies in the 4.0 directory.
See the blogs by Rick Strahl and Scott Hanselman on this topic.
You can also find the specific versions in:
C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework\.NETFramework
回答2:
EDIT: This answer was correct until mid-2013, but you may have a more recent version since the big msbuild change. See the answer from Jonny Leeds for more details.
The version under C:\Windows\Microsoft.NET\Framework\v4.0.30319 actually is .NET 4.5. It's a little odd, but certainly mscorlib there contains AsyncTaskMethodBuilder etc which are used for async.
.NET 4.5 effectively overwrites .NET 4.
回答3:
.NET 4.5 is not a side-by-side version, it replaces the assemblies for 4.0. Much like .NET 3.0, 3.5 and 3.5SP1 replaced the assemblies for 2.0. And added some new ones. The CLR version is still 4.0.30319. You only care about the reference assemblies, they are in c:\program files\reference assemblies.
回答4:
Whilst the above answers are correct its worth noting that MSBuild has changed and it no longer ships with the .net framework, it comes either stand alone or with visual studio. As a result it's binaries have moved... so the one you get under the 4.0.303619 directory is actually the old one!
I've just been caught out by this - I found automatic binding redirects were only working when running from VisualStudio but not when running msbuild from the command line... the clue was that binding redirects were added in VS 2013 (for that read .net framework 4.5). If you open up a vs command prompt you'll see it now gets it from program files as the other article mentions. Whereas I was using a batch file on my path which linked to the old version.
Version numbers
Under framework:
PS C:\Windows\Microsoft.NET\Framework\v4.0.30319> .\msbuild.exe -version
Microsoft (R) Build Engine version 4.0.30319.33440
[Microsoft .NET Framework, version 4.0.30319.34014]
Copyright (C) Microsoft Corporation. All rights reserved.
4.0.30319.33440PS C:\Windows\Microsoft.NET\Framework\v4.0.30319>
Under program files:
PS C:\Program Files (x86)\MSBuild\12.0\Bin> .\MSBuild.exe -version
Microsoft (R) Build Engine version 12.0.21005.1
[Microsoft .NET Framework, version 4.0.30319.34014]
Copyright (C) Microsoft Corporation. All rights reserved.
12.0.21005.1PS C:\Program Files (x86)\MSBuild\12.0\Bin>
回答5:
The webpage is incorrect and I have pointed this out to MS and they will get it changed.
As already stated above .NET 4.5 is an in-place upgrade of 4.0 so you will only have Microsoft.NET\Framework\v4.0.30319.
The ToolVersion for MSBuild remains at "4.0".
回答6:
The official way to find out if you have 4.5 installed (and not 4.0) is in the registry keys :
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\NET Framework Setup\NDP\v4\Full
Relesae DWORD needs to be bigger than 378675 Here is the Microsoft doc for it
all the other answers of checking the minor version after 4.0.30319.xxxxx seem correct though (msbuild.exe -version , or properties of clr.dll), i just needed something documented (not a blog)
来源：https://stackoverflow.com/questions/12070518/where-is-the-net-framework-4-5-directory