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• Finding Common Phrases in SQL Server TEXT Column

  - by regex

  Short Desc: I'm curious to see if I can use SQL Analysis services or some other SQL Server service to mine some data for me that will show commonalities between SQL TEXT fields in a dataset. Long Desc I am looking at a subset of data that consists of about 10,000 rows of TEXT blobs which are used as a notes column in a issue tracking (ticketing) software. I would like to use something out of the box (without having to build something) that might be able to parse through all of the rows and find commonly used byte sequences in the "Notes" column. In other words, I want to find commonly used phrases (two to three word phrases, so 9 - 20 character sections of the TEXT blob). This will help me better determine if associate's notes contain similar phrases (troubleshooting techniques) that we could standardize in our troubleshooting process flow. Closing Note I'd really rather not build an application to do this as my method will probably not be the most efficient way to do it. Hopefully all this makes sense. Please let me know in the comments if anything needs clarification.

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• Backreferences in lookbehind

  - by polygenelubricants

  Can you use backreferences in a lookbehind? Let's say I want to split wherever behind me a character is repeated twice. String REGEX1 = "(?<=(.)\\1)"; // DOESN'T WORK! String REGEX2 = "(?<=(?=(.)\\1)..)"; // WORKS! System.out.println(java.util.Arrays.toString( "Bazooka killed the poor aardvark (yummy!)" .split(REGEX2) )); // prints "[Bazoo, ka kill, ed the poo, r aa, rdvark (yumm, y!)]" Using REGEX2 (where the backreference is in a lookahead nested inside a lookbehind) works, but REGEX1 gives this error at run-time: Look-behind group does not have an obvious maximum length near index 8 (?<=(.)\1) ^ This sort of make sense, I suppose, because in general the backreference can capture a string of any length (if the regex compiler is a bit smarter, though, it could determine that \1 is (.) in this case, and therefore has a finite length). So is there a way to use a backreference in a lookbehind? And if there isn't, can you always work around it using this nested lookahead? Are there other commonly-used techniques?

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• HttpWebRequest Timeouts After Ten Consecutive Requests

  - by Bob Mc

  I'm writing a web crawler for a specific site. The application is a VB.Net Windows Forms application that is not using multiple threads - each web request is consecutive. However, after ten successful page retrievals every successive request times out. I have reviewed the similar questions already posted here on SO, and have implemented the recommended techniques into my GetPage routine, shown below: Public Function GetPage(ByVal url As String) As String Dim result As String = String.Empty Dim uri As New Uri(url) Dim sp As ServicePoint = ServicePointManager.FindServicePoint(uri) sp.ConnectionLimit = 100 Dim request As HttpWebRequest = WebRequest.Create(uri) request.KeepAlive = False request.Timeout = 15000 Try Using response As HttpWebResponse = DirectCast(request.GetResponse, HttpWebResponse) Using dataStream As Stream = response.GetResponseStream() Using reader As New StreamReader(dataStream) If response.StatusCode <> HttpStatusCode.OK Then Throw New Exception("Got response status code: " + response.StatusCode) End If result = reader.ReadToEnd() End Using End Using response.Close() End Using Catch ex As Exception Dim msg As String = "Error reading page """ & url & """. " & ex.Message Logger.LogMessage(msg, LogOutputLevel.Diagnostics) End Try Return result End Function Have I missed something? Am I not closing or disposing of an object that should be? It seems strange that it always happens after ten consecutive requests. Notes: In the constructor for the class in which this method resides I have the following: ServicePointManager.DefaultConnectionLimit = 100 If I set KeepAlive to true, the timeouts begin after five requests. All the requests are for pages in the same domain. EDIT I added a delay between each web request of between two and seven seconds so that I do not appear to be "hammering" the site or attempting a DOS attack. However, the problem still occurs.

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• Eclipse plugin development for Eclipse

  - by Raven

  Hi, how do I start to develop a plugin for Eclipse? I need a tool which isn't out there yet for my further development... so my main concerns are: -How to add a perspective? -How to add menu items? -How to add a view into the "Show Views" menu? -How to add to the preference pane? -How do I get information, like * where is the workspace? * which files are open in the editor? * which projects are collapsed / expanded in the left projects view? * ..... -Which conventions (naming...) should I consider? -How to set up update site/deployment? Can you give me some hints, links, tutorials.... Dont get me wrong. I am using Eclipse RCP for developing stand alone apps for quite some time, so I am familiar with the techniques, but I never started to develop a plugin for Eclipse itself. Thanks

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• Re-using aggregate level formulas in SQL - any good tactics?

  - by Cade Roux

  Imagine this case, but with a lot more component buckets and a lot more intermediates and outputs. Many of the intermediates are calculated at the detail level, but a few things are calculated at the aggregate level: DECLARE @Profitability AS TABLE ( Cust INT NOT NULL ,Category VARCHAR(10) NOT NULL ,Income DECIMAL(10, 2) NOT NULL ,Expense DECIMAL(10, 2) NOT NULL ) ; INSERT INTO @Profitability VALUES ( 1, 'Software', 100, 50 ) ; INSERT INTO @Profitability VALUES ( 2, 'Software', 100, 20 ) ; INSERT INTO @Profitability VALUES ( 3, 'Software', 100, 60 ) ; INSERT INTO @Profitability VALUES ( 4, 'Software', 500, 400 ) ; INSERT INTO @Profitability VALUES ( 5, 'Hardware', 1000, 550 ) ; INSERT INTO @Profitability VALUES ( 6, 'Hardware', 1000, 250 ) ; INSERT INTO @Profitability VALUES ( 7, 'Hardware', 1000, 700 ) ; INSERT INTO @Profitability VALUES ( 8, 'Hardware', 5000, 4500 ) ; SELECT Cust ,Profit = SUM(Income - Expense) ,Margin = SUM(Income - Expense) / SUM(Income) FROM @Profitability GROUP BY Cust SELECT Category ,Profit = SUM(Income - Expense) ,Margin = SUM(Income - Expense) / SUM(Income) FROM @Profitability GROUP BY Category SELECT Profit = SUM(Income - Expense) ,Margin = SUM(Income - Expense) / SUM(Income) FROM @Profitability Notice how the same formulae have to be used at the different aggregation levels. This results in code duplication. I have thought of using UDFs (either scalar or table valued with an OUTER APPLY, since many of the final results may share intermediates which have to be calculated at the aggregate level), but in my experience the scalar and multi-statement table-valued UDFs perform very poorly. Also thought about using more dynamic SQL and applying the formulas by name, basically. Any other tricks, techniques or tactics to keeping these kinds of formulae which need to be applied at different levels in sync and/or organized?

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• Help me find an appropriate ruby/python parser generator

  - by Geo

  The first parser generator I've worked with was Parse::RecDescent, and the guides/tutorials available for it were great, but the most useful feature it has was it's debugging tools, specifically the tracing capabilities ( activated by setting $RD_TRACE to 1 ). I am looking for a parser generator that can help you debug it's rules. The thing is, it has to be written in python or in ruby, and have a verbose mode/trace mode or very helpful debugging techniques. Does anyone know such a parser generator ? EDIT: when I said debugging, I wasn't referring to debugging python or ruby. I was referring to debugging the parser generator, see what it's doing at every step, see every char it's reading, rules it's trying to match. Hope you get the point. BOUNTY EDIT: to win the bounty, please show a parser generator framework, and illustrate some of it's debugging features. I repeat, I'm not interested in pdb, but in parser's debugging framework. Also, please don't mention treetop. I'm not interested in it.

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• GRAPH PROBLEM: find an algorithm to determine the shortest path from one point to another in a recta

  - by newba

  I'm getting such an headache trying to elaborate an appropriate algorithm to go from a START position to a EXIT position in a maze. For what is worth, the maze is rectangular, maxsize 500x500 and, in theory, is resolvable by DFS with some branch and bound techniques ... 10 3 4 7 6 3 3 1 2 2 1 0 2 2 2 4 2 2 5 2 2 1 3 0 2 2 2 2 1 3 3 4 2 3 4 4 3 1 1 3 1 2 2 4 2 2 1 Output: 5 1 4 2 Explanation: Our agent looses energy every time he gives a step and he can only move UP, DOWN, LEFT and RIGHT. Also, if the agent arrives with a remaining energy of zero or less, he dies, so we print something like "Impossible". So, in the input 10 is the initial agent's energy, 3 4 is the START position (i.e. column 3, line 4) and we have a maze 7x6. Think this as a kind of labyrinth, in which I want to find the exit that gives the agent a better remaining energy (shortest path). In case there are paths which lead to the same remaining energy, we choose the one which has the small number of steps, of course. I need to know if a DFS to a maze 500x500 in the worst case is feasible with these limitations and how to do it, storing the remaining energy in each step and the number of steps taken so far. The output means the agent arrived with remaining energy= 5 to the exit pos 1 4 in 2 steps. If we look carefully, in this maze it's also possible to exit at pos 3 1 (column 3, row 1) with the same energy but with 3 steps, so we choose the better one. With these in mind, can someone help me some code or pseudo-code? I have troubles working this around with a 2D array and how to store the remaining energy, the path (or number of steps taken)....

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• Google Code Jam 2010 Large DataSets Take Too Long to Submit

  - by Travis

  Hey Guys, I'm participating in the 2010 code jam and I solved two of the problems for the small data sets, but I'm not even close to solving the large data sets in the 8 minute time frame. I'm wondering if anyone out there has solved the large data set: What hardware were you running on? What language were you running on? What performance tuning techniques did you do on your code to run as fast as possible? I'm writing the solutions in Ruby, which is not my day to day language, and executing them on my Macbook Pro. My solutions for problem A and problem C are on github at http://github.com/tjboudreaux/codejam2010. I'd appreciate any suggestions that you may have. FWIW, I have alot of experience in C++ from college, my primary language is PHP, and my "sandbox" language is Ruby. Was I just a bit ambitious by taking a shot at this in Ruby, not knowing where the language struggles for performance, or does anyone see anything that's a redflag as to why I can't complete the large dataset in time to submit.

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• XPath with optional tbody element

  - by Phrogz

  As in this Stack Overflow answer imagine that you need to select a particular table and then all the rows of it. Due to the permissiveness of HTML, all three of the following are legal markup: <table id="foo"><tr>...</tr></table> <table id="foo"><tbody><tr>...</tr></tbody></table> <table id="foo"><tr>...</tr><tbody><tr>...</tr></tbody></table> You are worried about tables nested in tables, and so don't want to use an XPath like table[@id="foo"]//tr. If you could specify your desired XPath as a regex, it might look something like: table[@id="foo"](/tbody)?/tr In general, how can you specify an XPath expression that allows an optional element in the hierarchy of a selector? To be clear, I'm not trying to solve a real-world problem or select a specific element of a specific document. I'm asking for techniques to solve a class of problems.

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• Stack Overflow on Marshal.PtrToStructure reading wmv files

  - by Nick Udell

  Hi, I'm using a frame grabber class in order to capture and process each frame in a video. The class can be found here: http://www.codeproject.com/KB/graphics/FrameGrabber.aspx I'm having issues with running it, however. When loading the file, it attempts to marshal a video format pointer into a VideoInfoHeader (I'm using DirectShow.Net). The code that does this is as follows: videoInfo = (VideoInfoHeader)Marshal.PtrToStructure(mediaType.formatPtr, typeof(VideoInfoHeader)); When I run this it immediately crashes out of the debugging environment, probably with a stack overflow. When stepping through I can see that the formatPtr always equals 93, though I do not know what to make of this as I am fairly new to marshalling. I have checked that the video runs fine in Windows Media Player. This is essential in finding the dimensions of the video and also the size of the header, which needs to be skipped before the frames can be read. I am running Windows 7 x64. Any help on this would be much appreciated, I must've tried fifteen different frame grabbing techniques.

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• C# .NET : Is using the .NET Image Conversion enough?

  - by contactmatt

  I've seen a lot of people try to code their own image conversion techniques. It often seems to be very complicated, and ends up using GDI+ funciton calls, and manipulating bits of the image. This has got me wondering if I am missing something in the simplicity of .NET's image conversion call when saving an image. Here's the code I have Bitmap tempBmp = new Bitmap("c:\temp\img.jpg"); Bitmap bmp = new Bitmap(tempBmp, 800, 600); bmp.Save(c:\temp\img.bmp, //extension depends on format ImageFormat.Bmp) //These are all the ImageFormats I allow conversion to within the program. Ignore the syntax for a second ;) ImageFormat.Gif) //or ImageFormat.Jpeg) //or ImageFormat.Png) //or ImageFormat.Tiff) //or ImageFormat.Wmf) //or ImageFormat.Bmp)//or ); This is all I'm doing in my image conversion. Just setting the location of where the image should be saved, and passing it an ImageFormat type. I've tested it the best I can, but I'm wondering if I am missing anything in this simple format conversion, or if this is suffice?

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• How to suggest changes as a recently-hired employee ?

  - by ereOn

  Hi, I was recently hired in a big company (thousands of people, to give an idea of the size). They said they hired me because of my rigor and because I was, despite my youngness (i'm 25), experienced as a C/C++ programer. Now that I'm in, I can see that the whole system is old and often uses obsolete technologies. There is no naming convention (files, functions, variables, ...), they don't use Version Control, don't use exceptions or polymorphism and it seems like almost everybody lost his passion (some of them are only 30 years old). I'd like to suggest somes changes but i don't want to be "the new guy that wants to change everything just because he doesn't want to fit in". I tried to "fit in", but actually, It takes me one week to do what I would do in one afternoon, just because of the poor tools we're forced to use. A lot my collegues never look at the new "things" and techniques that people use nowadays. It's like they just given up. The situation is really frustrating. Have you ever been in a similar situation and, if so, what advices would you give me ? Is there a subtle way of changing things without becoming the black sheep here ? Or should I just give up my passion and energy as well ? Thank you.

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• What does it mean that "Lisp can be written in itself?"

  - by Mason Wheeler

  Paul Graham wrote that "The unusual thing about Lisp-- in fact, the defining quality of Lisp-- is that it can be written in itself." But that doesn't seem the least bit unusual or definitive to me. ISTM that a programming language is defined by two things: Its compiler or interpreter, which defines the syntax and the semantics for the language by fiat, and its standard library, which defines to a large degree the idioms and techniques that skilled users will use when writing code in the language. With a few specific exceptions, (the non-C# members of the .NET family, for example,) most languages' standard libraries are written in that language for two very good reasons: because it will share the same set of syntactical definitions, function calling conventions, and the general "look and feel" of the language, and because the people who are likely to write a standard library for a programming language are its users, and particularly its designer(s). So there's nothing unique there; that's pretty standard. And again, there's nothing unique or unusual about a language's compiler being written in itself. C compilers are written in C. Pascal compilers are written in Pascal. Mono's C# compiler is written in C#. Heck, even some scripting languages have implementations "written in itself". So what does it mean that Lisp is unusual in being written in itself?

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• HOWTO - Compare a date string to datetime in SQL Server?

  - by Guy

  In SQL Server I have a DATETIME column which includes a time element. Example: '14 AUG 2008 14:23:019' What is the best method to only select the records for a particular day, ignoring the time part? Example: (Not safe, as it does not match the time part and returns no rows) DECLARE @p_date DATETIME SET @p_date = CONVERT( DATETIME, '14 AUG 2008', 106 ) SELECT * FROM table1 WHERE column_datetime = @p_date Note: Given this site is also about jotting down notes and techniques you pick up and then forget, I'm going to post my own answer to this question as DATETIME stuff in MSSQL is probably the topic I lookup most in SQLBOL. Update Clarified example to be more specific. Edit Sorry, But I've had to down-mod WRONG answers (answers that return wrong results). @Jorrit: WHERE (date>'20080813' AND date<'20080815') will return the 13th and the 14th. @wearejimbo: Close, but no cigar! badge awarded to you. You missed out records written at 14/08/2008 23:59:001 to 23:59:999 (i.e. Less than 1 second before midnight.)

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• Teach Markup or use a WYSIWYG editor?

  - by Atomiton

  When it comes to WYSIWYG editors WYSI rarely WYG. The problem I always have is when people paste in formatted text from word. Ideally, what I'm looking for is a way for people to input text into the document while at the same time teaching them structure... I just don't know if that's a realistic goal ( compared to cut n' paste ) I'm curious if people have found using something other than WYSIWYG editors ( take SO, for example ) has worked for REAL WORLD USERS. I'm not talking about programmers, developers and experience internet users... I'm talking about your average user. I'd be interested in best practices when it comes to getting users to enter content... and I'd love it if someone could point me to some good editors/examples. there are lots of choices when it comes to WYSIWYG ( ckEditor, FreeTextBox, TinyMCE ) but I don't hear a lot about SO-like techniques. Does adding that small barrier scares users away? Is it too difficult to teach people to mark up their text? Is it easier to teach them html? Is a BBCode implementation a good idea? What are some Pros/Cons to wysiwyg/markup. What approach have others used?

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• What Scheme Does Ghuloum Use?

  - by Don Wakefield

  I'm trying to work my way through Compilers: Backend to Frontend (and Back to Front Again) by Abdulaziz Ghuloum. It seems abbreviated from what one would expect in a full course/seminar, so I'm trying to fill in the pieces myself. For instance, I have tried to use his testing framework in the R5RS flavor of DrScheme, but it doesn't seem to like the macro stuff: src/ghuloum/tests/tests-driver.scm:6:4: read: illegal use of open square bracket I've read his intro paper on the course, An Incremental Approach to Compiler Construction, which gives a great overview of the techniques used, and mentions a couple of Schemes with features one might want to implement for 'extra credit', but he doesn't mention the Scheme he uses in the course. Update I'm still digging into the original question (investigating options such as Petit Scheme suggested by Eli below), but found an interesting link relating to Gholoum's work, so I am including it here. [Ikarus Scheme](http://en.wikipedia.org/wiki/Ikarus_(Scheme_implementation)) is the actual implementation of Ghuloum's ideas, and appears to have been part of his Ph.D. work. It's supposed to be one of the first implementations of R6RS. I'm trying to install Ikarus now, but the configure script doesn't want to recognize my system's install of libgmp.so, so my problems are still unresolved. Example The following example seems to work in PLT 2.4.2 running in DrEd using the Pretty Big (require lang/plt-pretty-big) (load "/Users/donaldwakefield/ghuloum/tests/tests-driver.scm") (load "/Users/donaldwakefield/ghuloum/tests/tests-1.1-req.scm") (define (emit-program x) (unless (integer? x) (error "---")) (emit " .text") (emit " .globl scheme_entry") (emit " .type scheme_entry, @function") (emit "scheme_entry:") (emit " movl $~s, %eax" x) (emit " ret") ) Attempting to replace the require directive with #lang scheme results in the error message foo.scm:7:3: expand: unbound identifier in module in: emit which appears to be due to a failure to load tests-driver.scm. Attempting to use #lang r6rs disables the REPL, which I'd really like to use, so I'm going to try to continue with Pretty Big. My thanks to Eli Barzilay for his patient help.

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• Computing complex math equations in python

  - by dassouki

  Are there any libraries or techniques that simplify computing equations ? Take the following two examples: F = B * { [ a * b * sumOf (A / B ''' for all i ''' ) ] / [ sumOf(c * d * j) ] } where: F = cost from i to j B, a, b, c, d, j are all vectors in the format [ [zone_i, zone_j, cost_of_i_to_j], [..]] This should produce a vector F [ [1,2, F_1_2], ..., [i,j, F_i_j] ] T_ij = [ P_i * A_i * F_i_j] / [ SumOf [ Aj * F_i_j ] // j = 1 to j = n ] where: n is the number of zones T = vector [ [1, 2, A_1_2, P_1_2], ..., [i, j, A_i_j, P_i_j] ] F = vector [1, 2, F_1_2], ..., [i, j, F_i_j] so P_i would be the sum of all P_i_j for all j and Aj would be sum of all P_j for all i I'm not sure what I'm looking for, but perhaps a parser for these equations or methods to deal with multiple multiplications and products between vectors? To calculate some of the factors, for example A_j, this is what i use from collections import defaultdict A_j_dict = defaultdict(float) for A_item in TG: A_j_dict[A_item[1]] += A_item[3] Although this works fine, I really feel that it is a brute force / hacking method and unmaintainable in the case we want to add more variables or parameters. Are there any math equation parsers you'd recommend? Side Note: These equations are used to model travel. Currently I use excel to solve a lot of these equations; and I find that process to be daunting. I'd rather move to python where it pulls the data directly from our database (postgres) and outputs the results into the database. All that is figured out. I'm just struggling with evaluating the equations themselves. Thanks :)

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• Debug NAudio MP3 reading difference?

  - by Conrad Albrecht

  My code using NAudio to read one particular MP3 gets different results than several other commercial apps. Specifically: My NAudio-based code finds ~1.4 sec of silence at the beginning of this MP3 before "audible audio" (a drum pickup) starts, whereas other apps (Windows Media Player, RealPlayer, WavePad) show ~2.5 sec of silence before that same drum pickup. The particular MP3 is "Like A Rolling Stone" downloaded from Amazon.com. Tested several other MP3s and none show any similar difference between my code and other apps. Most MP3s don't start with such a long silence so I suspect that's the source of the difference. Debugging problems: I can't actually find a way to even prove that the other apps are right and NAudio/me is wrong, i.e. to compare block-by-block my code's results to a "known good reference implementation"; therefore I can't even precisely define the "error" I need to debug. Since my code reads thousands of samples during those 1.4 sec with no obvious errors, I can't think how to narrow down where/when in the input stream to look for a bug. The heart of the NAudio code is a P/Invoke call to acmStreamConvert(), which is a Windows "black box" call which I can't think how to error-check. Can anyone think of any tricks/techniques to debug this?

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• I write barely functional scripts that tend to not be resuable and make the baby jesus cry. Please h

  - by maxxpower

  I received a request to add around 100 users to a linux box the users are already in ldap so I can't just use newusers and point it at a text file. Another admin is taking care of the ldap piece so all I have to do is create all the home directories and chown them to the correct user once he adds the users to the box. creating the directories isn't a problem, but I'd like a more elegant script for chowning them to the correct user. what I have currently basically looks like chown -R testuser1 testgroup1 /home/tetsuser1; chown -R testuser2 testgroup2 /home/testgroup2; chown -R testsuser3 testgroup1 /home/testuser3 bascially I took the request that the user name and group name popped it into excel added a column of "chown -R" to the front, then added a column of "/", copied and pasted the username column after it and then added a column of ";" and dragged it down to the second to last row. Popped it into notepad ran some quick find and replaces and in less than a minute I have a completed request and a sad empty feeling. I know this was a really ghetto method and I'm trying to get away from using excel to avoid learning new scripting techniques so here's my real question. tl;dr I made 100 home directories and chowned them to the correct users, but it was ugly. Actual question below. You have a file named idlist that looks like this (only with say 1000 users and real usernames and groups) testuser1 testgroup1 testuser2 testgroup2 testuser3 testgroup1 write a script that creates home directories for all the users and chowns the created directories to the correct user and group. To make the directories I used the following(feel free to flame/correct me on this as well. ) var= 'cut -f1 -d" " idlist' (I used backticks not apostrophes around the cut command) mkdir $var

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• How can I catch an invalid fgetpos call as a C++ exception on Windows?

  - by Brent Arias

  In Visual C++ 2008, I want to "catch" an exception generated as shown here: try { int foo = 20; ::fgetpos(0, (fpos_t*)&foo); } //... Here are adjustments I've made to attempt a successful catch: SEH is activated (/eha) I've added a catch(...) I've added a _set_se_translator vector. I've added/adjusted to SEH syntax: __try / __except(EXCEPTION_EXECUTE_HANDLER) In short, I've tried "everything in the book" and I still can't catch the exception. If I replace the call to ::fgetpos with int hey = foo / 0 then suddenly all of the above techniques work as expected. So the exception I'm dealing with from ::fgetpos is somehow "extra special." Can someone explain why this ::fgetpos error seems uncatchable, and how to work around it? update When executed in the VS IDE, the output window doesn't name an exception. All it says is this: Microsoft Visual Studio C Runtime Library has detected a fatal error in MyProgram.exe. Not very helpful. When I run the console app from the command line, I get a crash dialogue. The "problem details" section of the dialogue includes this information: Problem Event Name: BEX Exception Offset:0002fd30 Exception Code: c0000417 Exception Data: 00000000 Additional Information 1:69ad Additional Information 2:69addfb19767b2221c8e3e7a5cd2f4ae Additional Information 3:b1ff Additional Information 4:b1ffca30cadddc78c19f19b6d150997f

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• Update a PDF to include an encrypted, hidden, unique identifier?

  - by Dave Jarvis

  Background The idea is this: Person provides contact information for online book purchase Book, as a PDF, is marked with a unique hash Person downloads book PDF passwords are annoying and extremely easy to circumvent. The ideal process would be something like: Generate hash based on contact information Store contact information and hash in database Acquire book lock Update an "include" file with hash text Generate book as PDF (using pdflatex) Apply hash to book Release book lock Send email with book download link Technologies The following technologies can be used (other programming languages are possible, but libraries will likely be limited to those supplied by the host): C, Java, PHP LaTeX files PDF files Linux Question What programming techniques (or open source software) should I investigate to: Embed a unique hash (or other mark) to a PDF Create a collusion-attack resistant mark Develop a non-fragile (e.g., PDF -> EPS -> PDF still contains the mark) solution Research I have looked at the following possibilities: Steganography Natural Language Processing (NLP) Convert blank pages in PDF to images; mark those images; reassemble PDF LaTeX watermark package ImageMagick Steganograhy requires keeping a master copy of the images, and I'm not sure if the watermark would survive PDF -> EPS -> PDF, or other types of conversion. LaTeX creates an image cache, so any steganographic process would have to intercept that process somehow. NLP introduces grammatical errors. Inserting blank pages as images is immediately suspect; it is easy to replace suspicious blank pages. The LaTeX watermark package draws visible marks. ImageMagick draws visible marks. What other solutions are possible? Related Links http://www.tcpdf.org/ invisible watermarks in images Thank you!

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• Generic object to object mapping with parametrized constructor

  - by Rody van Sambeek

  I have a data access layer which returns an IDataRecord. I have a WCF service that serves DataContracts (dto's). These DataContracts are initiated by a parametrized constructor containing the IDataRecord as follows: [DataContract] public class DataContractItem { [DataMember] public int ID; [DataMember] public string Title; public DataContractItem(IDataRecord record) { this.ID = Convert.ToInt32(record["ID"]); this.Title = record["title"].ToString(); } } Unfortanately I can't change the DAL, so I'm obliged to work with the IDataRecord as input. But in generat this works very well. The mappings are pretty simple most of the time, sometimes they are a bit more complex, but no rocket science. However, now I'd like to be able to use generics to instantiate the different DataContracts to simplify the WCF service methods. I want to be able to do something like: public T DoSomething<T>(IDataRecord record) { ... return new T(record); } So I'd tried to following solutions: Use a generic typed interface with a constructor. doesn't work: ofcourse we can't define a constructor in an interface Use a static method to instantiate the DataContract and create a typed interface containing this static method. doesn't work: ofcourse we can't define a static method in an interface Use a generic typed interface containing the new() constraint doesn't work: new() constraint cannot contain a parameter (the IDataRecord) Using a factory object to perform the mapping based on the DataContract Type. does work, but: not very clean, because I now have a switch statement with all mappings in one file. I can't find a real clean solution for this. Can somebody shed a light on this for me? The project is too small for any complex mapping techniques and too large for a "switch-based" factory implementation.

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• Best practices for managing updating a database with a complex set of changes

  - by Sarge

  I am writing an application where I have some publicly available information in a database which I want the users to be able to edit. The information is not textual like a wiki but is similar in concept because the edits bring the public information increasingly closer to the truth. The changes will affect multiple tables and the update needs to be automatically checked before affecting the public tables. I'm working on the design and I'm wondering if there are any best practices that might help with some particular issues. I want to provide undo capability. I want to show the user the combined result of all their changes. When the user says they're done, I need to check the underlying public data to make sure it hasn't been changed by somebody else. My current plan is to have the user work in a set of tables setup to be a private working area. Once they're ready they can kick off a process to check everything and update the public tables. Undo can be recorded using Command pattern saving to a table. Are there any techniques I might have missed or useful papers or patterns? Thanks in advance!

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• Best Practice With JFrame Constructors?

  - by David Barry

  In both my Java classes, and the books we used in them laying out a GUI with code heavily involved the constructor of the JFrame. The standard technique in the books seems to be to initialize all components and add them to the JFrame in the constructor, and add anonymous event handlers to handle events where needed, and this is what has been advocated in my class. This seems to be pretty easy to understand, and easy to work with when creating a very simple GUI, but seems to quickly get ugly and cumbersome when making anything other than a very simple gui. Here is a small code sample of what I'm describing: public class FooFrame extends JFrame { JLabel inputLabel; JTextField inputField; JButton fooBtn; JPanel fooPanel; public FooFrame() { super("Foo"); fooPanel = new JPanel(); fooPanel.setLayout(new FlowLayout()); inputLabel = new JLabel("Input stuff"); fooPanel.add(inputLabel); inputField = new JTextField(20); fooPanel.add(inputField); fooBtn = new JButton("Do Foo"); fooBtn.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent e) { //handle event } }); fooPanel.add(fooBtn); add(fooPanel, BorderLayout.CENTER); } } Is this type of use of the constructor the best way to code a Swing application in java? If so, what techniques can I use to make sure this type of constructor is organized and maintainable? If not, what is the recommended way to approach putting together a JFrame in java?

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• How to read/write high-resolution (24-bit, 8 channel) .wav files in Java?

  - by dB'

  I'm trying to write a Java application that manipulates high resolution .wav files. I'm having trouble importing the audio data, i.e. converting the .wav file into an array of doubles. When I use a standard approach an exception is thrown. AudioFileFormat as = AudioSystem.getAudioFileFormat(new File("orig.wav")); --> javax.sound.sampled.UnsupportedAudioFileException: file is not a supported file type Here's the file format info according to soxi: dB$ soxi orig.wav soxi WARN wav: wave header missing FmtExt chunk Input File : 'orig.wav' Channels : 8 Sample Rate : 96000 Precision : 24-bit Duration : 00:00:03.16 = 303526 samples ~ 237.13 CDDA sectors File Size : 9.71M Bit Rate : 24.6M Sample Encoding: 32-bit Floating Point PCM Can anyone suggest the simplest method for getting this audio into Java? I've tried using a few techniques. As stated above, I've experimented with the Java AudioSystem (on both Mac and Windows). I've also tried using Andrew Greensted's WavFile class, but this also fails (WavFileException: Compression Code 3 not supported). One workaround is to convert the audio to 16 bits using sox (with the -b 16 flag), but this is suboptimal since it increases the noise floor. Incidentally, I've noticed that the file CAN be read by libsndfile. Is my best bet to write a jni wrapper around libsndfile, or can you suggest something quicker? Note that I don't need to play the audio, I just need to analyze it, manipulate it, and then write it out to a new .wav file. * UPDATE * I solved this problem by modifying Andrew Greensted's WavFile class. His original version only read files encoded as integer values ("format code 1"); my files were encoded as floats ("format code 3"), and that's what was causing the problem. I'll post the modified version of Greensted's code when I get a chance. In the meantime, if anyone wants it, send me a message.

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