Install every version or latest version is enough?

I'm very confused with 开发者_如何学JAVAdotnet framework installation.

Even though I've installed the latest version (4.0), some dotnet framework-based programs told me that I need to install version 1.1 or 2.0.

So, I'm curious to know whether I need to install every version of DotNet framework so that every kind of such program can run. Does it cause due to programmer's badly checks?

Thank you.

It really depends on what version of the framework that the application was designed to run on, there are a few versions of the framework and a few of the runtime. Sometimes an application can be written for .NET 3.5 but has references to libraries that were written against .NET 1.1 in which case you would need both installed.

There is a fair breakdown of the Framework, Runtime and Language reference In this Answer.

As I understand it, .NET 3.5 includes versions 2.0 and 3.0 as it builds upon them. However, .NET 4.0 has no dependencies on previous versions and therefore they were removed in order to reduce the installation size, which was a common deployment complaint.

If the version of the .NET Framework that the program was built against is not present on the computer, and it doesn't specify any supported versions in a configuration file, then the latest version of the .NET Framework will attempt to run it.

See these articles for more information:

• .NET Framework Versions and Dependencies
• Version Compatibility in the .NET Framework
• How to: Use an Application Configuration File to Target a .NET Framework Version