Where is the .NET 4.5 folder?
Looking at the %WINDIR%\Microsoft.NET\Framework directory used to be a simple way to check what versions of the .NET Framework were installed on a machine.
.NET 4.5 is an "in-place upgrade" of .NET 4. That means .NET 4.5 is still the v4 CLR and adds new libraries as well as improvements to the core CLR itself. As such, there no .NET 4.5 folder.
In-place upgrade means that the CLR is the same but new libraries are added as well as bug fixes and performance improvements.
The .NET Framework can version in two ways. There are "side by side installs" and there are "in place upgrades." A major version means side-by-side and a minor version means in-place.
Side-by-side means that different versions of .NET can live together on the same machine.
|Images from Scott Hanselman's blog|
Alternatively, you can download the .NET version checker tool from Scott Hanselman's SmallestDotnet.com or try this DOS command (it make up to a few minutes for the result to appear) -
wmic product where "Name like 'Microsoft .Net%'" get Name, Version
If you have to check the version programmatically, try this code sample from MSDN.