C# Discussion Boards - CodeProject

14-Sep-12 5:30

How can we detect from our program that a prerequired
program such as dotNetFrameWork3 or 4 is installed
and also is active now or not? thanks

Richard MacCutchan14-Sep-12 5:34

14-Sep-12 5:34

The system will do it for you. If the framework is not installed then your program will not even start.

One of these days I'm going to think of a really clever signature.

Shameel14-Sep-12 5:46

Shameel

14-Sep-12 5:46

Richard MacCutchan wrote:
your program will not even start.

Technically inaccurate.

It will indeed start and display a message box telling you that the required framework is missing. Smile | :)

Richard MacCutchan14-Sep-12 6:10

14-Sep-12 6:10

Shameel wrote:
Technically inaccurate.

On the contrary, the actual program will not start. The system will receive a request to start it, and the loader will check for prerequisites and abort the loading when it discovers that a required library is not present. The point being that the user code will never get control in order to 'see' this problem.

One of these days I'm going to think of a really clever signature.

Shameel14-Sep-12 9:01

Shameel

14-Sep-12 9:01

Richard MacCutchan wrote:
On the contrary, the actual program will not start.

The actual program WILL start and execute a native bootstrap that loads the mscoree.dll (which is Framework version agnostic). It is this dll that actually checks if the supported Runtime is installed and displays a message box if it is not installed.

Richard MacCutchan wrote:
the point being that the user code will never get control in order to 'see' this problem.

Agree.

Richard MacCutchan14-Sep-12 9:29

14-Sep-12 9:29

So the program still never gets started, the only thing that gets any control is the framework that is wrapped round the app. My point was to show that the user code has no way of checking whether a required feature is present or not. Which, after all, is what the questioner is asking about.

One of these days I'm going to think of a really clever signature.

Fred 3414-Sep-12 8:19

14-Sep-12 8:19

FrameWork was just an example.

Richard MacCutchan14-Sep-12 9:26

14-Sep-12 9:26

And I gave the answer based on that information. If you wish to discuss some other issue then maybe you could explain further.

One of these days I'm going to think of a really clever signature.

OriginalGriff14-Sep-12 6:24

OriginalGriff

14-Sep-12 6:24

The only way to do it is to write a native code pre-loader which checks the requirements you specify and only starts your porgram if they are met. But you can't do that in C# or any other .NET language as Richard has already said - you would need to use C or C++ most likely.

Ideological Purity is no substitute for being able to stick your thumb down a pipe to stop the water

Abhinav S14-Sep-12 8:17

Abhinav S

14-Sep-12 8:17

Create an installer for your program and let this installer check the required framework for you - Add Prerequisites of .NET Framework in Visual Studio Setup Project[^].

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Fred 3414-Sep-12 8:29

14-Sep-12 8:29

As I mentioned before, FrameWork was just an example. In general, how is it possible to check that a dll which is not even famous, is running or not?

Richard MacCutchan14-Sep-12 9:34

14-Sep-12 9:34

DLLs do not 'run', they are loaded by the system when an application attempts to call a function within the DLL. Alternatively an application can load the DLL and make 'unlinked' calls to functions using the LoadLibrary()[^] and associated functions. This is true in native applications but I'm not sure that it is particularly straightforward in .NET based applications.

Perhaps a clearer explanation of what you are trying to achieve would help.

One of these days I'm going to think of a really clever signature.

Fred 3414-Sep-12 9:56

14-Sep-12 9:56

You are right, assume that a program wants to check out a printer driver is loaded or not?

Paul Conrad14-Sep-12 10:25

Paul Conrad

14-Sep-12 10:25

Though Enumerating All Device Drivers in the System[^] is in C++, I'm sure you could implement this in C#. You may want to look into this.

A code sample at http://www.pinvoke.net/default.aspx/psapi.enumdevicedrivers[^] in C#, hope this sheds some light for you Smile | :)

"Any sort of work in VB6 is bound to provide several WTF moments." - Christian Graus

modified 14-Sep-12 16:33pm.

Richard MacCutchan14-Sep-12 22:49

14-Sep-12 22:49

Well, as Paul explains, you can enumerate all sorts of information in C++, which probably means you need to learn about P/Invoke[^]. However, you still have not explained what you are trying to achieve.

One of these days I'm going to think of a really clever signature.

jschell14-Sep-12 11:01

jschell

14-Sep-12 11:01

Based on your other responses your question is imprecise.

There are many things that at application either requires or desires.

The impact on the application on those depends on the nature of the item itself.

As an extreme example if you have compiled windows binary it will not run on a BASIC-STAMP. It is also ridiculous to even consider that case.

The needs can be broken into the following
1. It will always be on the target system
2. It will often be on the target system
3. It will sometimes be on the target system.

What your application does based on the above depends on the need. Choices are.
1. Do not run.
2. Run but do not enable certain functionality.
3. Run and provide default functionality.
4. Inform the user and ask them to install the functionality.

You can attempt to minimize problems by creating an appropriate installer. The nature of that installer depends on the decisions related to the above. But in general the installer must check for the specific functionality and then install it. How it does that still depends on the nature of the resource though.

And all of the above also is impacted by the license of the specific resources.