Develop Reference

C# documentation XML: Is there a DTD?

I'm writing XML documentation for a couple of C# projects. I want to be able to parse the file that comes out into HTML suitable for posting on GitHub Pages. I've got a pretty good handle on the parsing process itself, but I need an idea of all the elements that might show up in documentation.
I thought that a DTD might be the best resource for this, does that exist? Or is this all completely free-form?
I realize there are a few tools that already exist to do this, but I want finer control over the process and honestly it's good practice anyway.

XML validation is a product of some sort of application. The documentation comments in C# are just XML. It is the application that you parse/process the comments with that determines if there are any rules for what elements are allowed. There are multiple applications that can convert XML documentation comments into documentation, and you could even build your own if needed.
As mentioned, MSDN has a list of available elements. These are standardized across most parsers. If you need to add additional elements it is fine if you have a parser that can handle them. You could even add an XSD or DTD if you wanted for that application, if supported.

Comment template in VS2010

I have inherited an API which doesn't have proper comments, and I am working on changing that.
Anyone know if there is some sort of mechanism to add a default XML comments to all the members of a class or an assembly?
(I remember seeing something like that on a webcast and I think he might have used PowerShell script to achieve that.)
This way I can avoid lots of repetitive steps, and have everything in place to go and start writing just the comments.
Anyone has any better suggestions?

GhostDoc is pretty fantastic for XML documentation, although you'll need to purchase a copy to generate automatic documentation for all classes/members. The free version allows you to right click (or use a hotkey) on class or member and it will generate the documentation.

I've found GhostDoc to be pretty good.
Once you've run it over your code you then simply add details where required.
http://submain.com/products/ghostdoc.aspx

ASP.NET User-based Templates

Is there anyway to let users write their own aspx templates with my defined dynamic variables? Note that I don't want to use Web Forms (so there are no tags like <asp:button> etc).
In addition, I'd need a security solution so users can't change the system or do dangerous things like this.
Thanks.

Personally I would avoid using the ASPX engine for this. I would probably use either a really simple custom formatting solution (such as just a text file with %%VAR_NAME%% allowed for dynamic values), or I would look at a templating language such as Markdown (used by StackOverflow and others). BBCode is another option in a similar vein.
Allowing people to create ASPX templated pages on the fly seems like to much of a security issue to me. It would be hard to make sure you have closed all the possible attack vectors once they have direct access to the ASP.NET engine.
Since you didn't specify, I'm just guessing at your needs, so depending on the exact problem this may or may not be your best bet. If you include more details about the problem you are solving it would be easier to make suggestions.

Find all source hardcoded strings

I need to move all the hard coded strings in my source code in .resx files. Is there a tool that could help me find all the hardcoded strings within C# code?

ReSharper 5 is obvious a choice, but many tips must be set so as to achieve your goals,
Turn on solution wide analysis.
Go to ReSharper|Options|Code Inspection|Inspection Severity|Potential Code Quality Issues|Element is localizable set to Show as error.
Go back to Solution Explorer and click on the project (csproj).
In Properties panel under ReSharper category, set Localizable to Yes, Localizable Inspector to Pessimistic.
Then you can find almost all you need in Errors in Solution panel.
Hope this helps.

Or do a search based upon a regular expression like discussed here:
https://vosseburchttechblog.azurewebsites.net/index.php/2014/12/16/find-all-string-literals-in-c-code-files-but-not-the-ones-in-comments/
(?=(^((?!///).)*$)).*((".+?")|('.+?')).*

You could always do a search for the " sign in all the .cs files. That should get you to most of them, without too much noise.

This tool http://visuallocalizer.codeplex.com/ allows for batch-move strings to resources, together with other features. It is FOSS so maybe you can give it a try.
(I am involved)

Resharper 5.0 (Beta) allows you to move strings to resources (it has built in Localization feature). Give it a try. Beta works fine, i use it every day and have no problems. Best of all it's free until out of beta. I even recommend using night builds as they seem to be stable.
Software localization and globalization have always been tough and at times unwanted tasks for developers. ReSharper 5 greatly simplifies working with resources by providing a full stack of features for resx files and resource usages in C# and VB.NET code, as well as in ASP.NET and XAML markup.
Dedicated features include Move string to resource, Find usages of resource and other navigation actions. Combined with refactoring support, inspections and fixes, you get a convenient localization environment.

Some are found by FxCop. Not sure what its limits are, I think it depends on parameter and property names (eg: a property called "Text" is considered to be localized).

How to get all file attributes including author, title, mp3 tags, etc, in one sweep

I would like to write all meta data (including advanced summary properties) for my files in a windows folder to a csv file. Is there a way to collect all the attributes? I see mp3 files have a different set of attributes compared to jpg files. (c#)
This can also be a script (vb, perl)
Update: by looking at libextractor (thank you) I can see this can be achieved by writing different plugins for different type of files. I gather this meta data is not a simple collection...

In Perl, you can use MP3::Tag or MP3::Info

If you can cope w/ VB.Net: http://www.codeproject.com/KB/vb/mp3id3v1.aspx
If you can cope w/ C++/.Net: http://www.codeproject.com/KB/audio-video/mp3fileinfo.aspx
For either (assuming the C++) is compiled to .Net, you can use Reflector to disassemble the binary and convert it to C#. Check w/ the respective authors about their licenses first (usually Code Project articles are under an open license like CPOL).

In a library? Try libextractor if your software is GPL.

Ok, after the clarification edits, I would suggest looking at the introspection available in .Net. I will warn you however that I think you will get more satisfying results if you forgo introspection and define the specific properties that you want for the file types that you expect to see.
Since scripting is valid, then if this were my problem to solve I would use Powershell since the .net introspection is baked in.

It may not be worth it to add all of the data from a jpeg file (exif data). I would hand pick what attributes I wanted from those files.