I have a set of complex C++ classes.
After creating objects of the class, all the data can be saved on disk.
I want to load two such saved instances and tell if they are identical.
Any ideas on how to do this in a way that is maintainable?
I've tried doing sorted text reports that print all the data and compare that. The problem is fields can get added to the classes over time and its not possible to tell if the report is "complete".
Any way introspection or reflection can be used to accomplish this?
this is a complex problem which those wonderful guys at boost.org have already solved for you:
http://www.boost.org/doc/libs/1_58_0/libs/serialization/doc/index.html
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I have inherited a large base of SAS code. I need to reverse engineer to create some mapping document, so that given a field in the final output dataset, we can easily trace it all the way back to one of the inputs.
I can create it by hand, but can SAS automatically generate something like this?
No, I don't think there is any ready-made automated way of doing this.
Bear in mind that it is possible to create variables and pass them through a whole series of procs and data steps without mentioning them by name anywhere in the source code. Some sort of run-time analysis is therefore unavoidable.
Reeza's suggestion of using proc scaproc will yield some useful information for code executed within a single self-contained job running in a single SAS session, and the ATTR option in the record statement might be of some help to you when tracing the lineage of variables, but I'm afraid that however you approach this, it's going to take quite a lot of work.
Well, in my current project, the records are loaded from a database directly into QStandardItemModel and then view via QTreeView(). Everything works fine too. But I thought about the ram-memory. I think that the QStandardItemModel, including records, will be loaded into ram-memory. Similar to the data structure (for instance list), right? But what happens when I have large data sets? I read in Qt Documentation: Fetch More Example that I have to add items to the model in batches and preferably only when the items are needed by the view. It sounds good, but I have no idea how to do that. Does anyone of you know a few examples in python codes? Unfortunately, I do not understand the C ++ examples. Or does anyone know a better solution?
Don't get me wrong. I don't want a ready solution because I'm too lazy. No! I want to learn and work on it.
I am trying to create C++ code that allows User Input in selecting a variety of fields, then it will calculate many different angles and show the users the results, as well as a graph.
However, it has been suggested to us by our lecturer that it may be a good idea to write the code to these calculations etc in C++, then input the results into Excel.
Does anyone have any idea how to do this? Literally looking for a way for the user to fill in the required values on C++ and then to be AUTOMATICALLY taken to the excel file to show the results in the table and graph format.
If this is not possible, is there a way to display the results in the table and graph format through C++?
Thanks very much in advance
Excel provides COM interface which you can use from your C++ application.
This can be done in the way described in this article:
http://support.microsoft.com/kb/216686
This link might also be useful:
http://www.codeproject.com/Articles/10886/How-to-use-Managed-C-to-Automate-Excel
I think the second link would be better for you as its more of a step by step guide which should help you to workout the answer.
Use COM Automation to automate excel.
The best way to do this is to use the vole library by Matthew Wilson at
http://vole.sourceforge.net/
Take a look at the examples. I do not think there is an example for excel, but there is one for microsoft word at http://www.codeproject.com/KB/COM/VOLE_word.aspx
I have used vole in the past, and it makes it a whole lot easier
I have a huge text file (~5GB) which is the database for my program. During run this database is read completely many times with string functions like string::find(), string::at(), string::substr()...
The problem is that this text file cannot be loaded in one string, because string::max_size is definitely too small.
How would you implement this? I had the idea of loading a part to string->reading->closing->loading another part to same string->reading->closing->...
Is there a better/more efficient way?
How would you implement this?
With a real database, for instance SQLite. The performance improvement from having indexes is more than going to make up for your time learning another API.
Since this is a database, I'm assuming it'd have many records. That to me implies best idea would be to implement a data class for each records and populate a list/vector/etc depending upon how you plan to use it. I'd also look into persistent cache as the file is big.
And within in your container class of all records, you could implement search etc functions as you see fit. But as suggested for a db of this size, you're probably best of using a database.
I have to parse the XML file and build objects representation based on that, now once I get all these data I create entries in various database for these data objects. I have to do second pass over that for value as in the first pass all I could do is build the assets in various databases. and in second pass I get the values for all the data and put it in the database.
I have a feeling that this can be done in a single pass but I just want to see what are your opinions. As I am just a student who started with professional work, experienced ppl please help.
Can someone who have ideas or done similar work, please provide some light on the topic so that I can think over the possibility of the work and get the prototype going based on your suggestion.
Thanks a lot for your precious time, I honestly appreciate it.
You might be interested in learning several techniques of building XML parsers like DOM or SAX. As it is said in SAX description the only thing which requires second pass could be the XML validation but not the creating the tree.
Beside DOM and SAX parsing, you can use XQuery for querying data from XML files.It is fast, robust and efficient.
here is a link
You can use Qt Xml module for DOM ,SAX and XQuery, btw it is open source.
Another option is xml - C++ data binding, Here is the link.You can create C++ codes from definition directly.It is an elegant solution.
EDIT:
the latter one is at compile time.
You can also use Apache Licensed http://xmlbeansxx.touk.pl/. It works under Windows and Linux.
you could take a look at the somewhat simpler 'pull' api called stax instead of using sax (event based).