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  • Worked Example of Digital Signature Algorithm

    - by drelihan
    Hi Folks, Does anybody have a DSA worked example with simple values on how to calculate r,s and verify v == r. As this standard has been around awhile and is implemented in librarys e.g. the Java Cryptography Extension I'm finding it very hard to find an example of how the algorithm works. Compute r=(gk mod p) mod q Compute s=(k-1 * (x * r + i)) mod q Verifying a signature; again i is the input, and (r,s) is the signature. u1 = (s-1 * i) mod q u2 = (s-1 * r) mod q v = ((gu1 * yu2) mod p) mod q If v equals r, the signature is valid. Thanks,

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  • SQL update fields of one table from fields of another one.

    - by Nir
    I'm having two tables: A [ID, column1, column2, column3] B [ID, column1, column2, column3, column4] A table will always be subset of B table (meaning all columns of A are also in B). I want to update a record with a specific ID in B with their data from A for all columns of A. This ID exists both in A and B. Is there an UPDATE syntax or any other way to do that without specifying the column names, just saying "set all columns of A"? I'm using postgresql, so a specific non-standard command is also accepted (however, not preferred). Thanks.

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  • In MVC framworks (such as Ruby on Rails), does usually Model spell as singular and controller and vi

    - by Jian Lin
    I usually see Ruby on Rails books using script/generate model Story name:string link:string which is a singular Story, while when it is controller script/generate controller Stories index then the Story now is Stories, which is plural. Is this a standard on Ruby on Rails? Is it true in other MVC frameworks too, like CakePHP, Symfony, Django, or TurboGears? I see that in the book Rails Space, the controller is also called User, which is the same as the model name, and it is the only exception I see. Update: also, when scaffold is done on Ruby on Rails, then automatically, the model is singular and the controller and view are both plural.

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  • Preparing for Rails deployment

    - by Meltemi
    Getting ready to deploy a rails project on Mac OS X Leopard Server (such that it matters). Got a few questions for someone with Rails experience: where should directory containing the project go? inside the website's root folder or out? who should "own" that directory? www? root? something/someone else? hope to continue serving static pages via Apache... would like rails app to be served by mydomain/xxx/railsapp. is there a standard naming convention for 'xxx'? not expecting too much traffic to begin with...just like to keep things as simple as possible.

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  • Define the base class or base functionality of a dynamic proxy (e.g. Castle, LinFu)

    - by Graham
    Hi, I've asked this in the NHibernate forumns but I think this is more of a general question. NHibernate uses proxy generators (e.g. Castle) to create its proxy. What I'd like to do is to extend the proxy generated so that it implements some of my own custom behaviour (i.e. a comparer). I need this because the following standard .NET behaviour fails to produce the correct results: //object AC is a concrete class collection.Contains(AC) = true //object AP is a proxy with the SAME id and therefore represents the same instance as concrete AC collection.Contains(AP) = false If my comparer was implemented by AP (i.e. do id's match) then collection.Contains(AP) would return true, as I'd expect if proxies were implicit. (NB: For those who say NH inherits from your base class, then yes it does, but NH can also inherit from an interface - which is what we're doing) I'm not at all sure this is possible or where to start. Is this something that can be done in any of the common proxy generators that NH uses?

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  • Initializing structs in C++

    - by Neil Butterworth
    As an addendum to this question, what is going on here: #include <string> using namespace std; struct A { string s; }; int main() { A a = {0}; } Obviously, you can't set a std::string to zero. Can someone provide an explanation (backed with references to the C++ Standard, please) about what is actually supposed to happen here? And then explain for example): int main() { A a = {42}; } Are either of these well-defined? Once again an embarrassing question for me - I always give my structs constructors, so the issue has never arisen before.

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  • is memset(ary,0,length) a portable way of inputting zero in double array

    - by monkeyking
    The following code uses memset to set all the bits to zero #include <iostream> #include <cstring> int main(){ int length = 5; double *array = new double[length]; memset(array,0,sizeof(double)*length); for(int i=0;i<length;i++) if(array[i]!=0.0) std::cerr<< "not zero in: " <<i <<std::endl; return 0; } Can I assume that this will work on all platforms? Does the double datatype always correspond to the ieee-754 standard? thanks

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  • Package <blah> does not exist error - NetBeans 6.8 & Windows 7

    - by BenMc
    I'm using NetBeans 6.8 on Windows 7. I upgraded from WinXP and NetBeans 6.7. Now my existing java web app project is no longer able to import/find the packages I've developed - I receive a 'Package ,blah. does not exist' and yet the packages do exist, worked fine in NetBeans 6.7 and the project still compiles and runs OK. I've tried changing the Java Platform/JDK from 1.6.0_10 back to JDK 1.5.0_22 but I still receive errors package does not exist. All other 'standard' libraries and packages are able to be imported and used OK ... eg Struts, Hibernate

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  • Using member variables inherited from a templated base class (C++)

    - by Aaron Becker
    I'm trying to use member variables of a templated base class in a derived class, as in this example: template <class dtype> struct A { int x; }; template <class dtype> struct B : public A<dtype> { void test() { int id1 = this->x; // always works int id2 = A<dtype>::x; // always works int id3 = B::x; // always works int id4 = x; // fails in gcc & clang, works in icc and xlc } }; gcc and clang are both very picky about using this variable, and require either an explicit scope or the explicit use of "this". With some other compilers (xlc and icc), things work as I would expect. Is this a case of xlc and icc allowing code that's not standard, or a bug in gcc and clang?

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  • Unit testing huge applications - Proven methodologies?

    - by NLV
    Hello members I've been working in windows forms applications and ASP.Net applications for the past 10 months. I've always wondered how to perform proper unit testing on the complete application in a robust manner covering all the scenarios. I've the following questions regarding them - What are the standard mechanisms in performing unit testing and writing test cases? Does the methodologies change based on the application nature such as Windows Forms, Web applications etc? What is the best approach to make sure we cover all the scenarios? Any popular books on this? Popular tools for performing unit testing?

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  • How do I use Amazon's new RRS for S3?

    - by pbarney
    Reduced Redundancy Storage (RRS) is a new service from Amazon that is a bit cheaper than S3 because there is less redundancy. However, I can not find any information on how to specify that my data should use RRS rather than standard S3. In fact, there doesn't seem to be any website interface for an S3 services. If I log into AWS, there are only options for EC2, Elastic MapReduce, CloudFront and RDS, none of which I use. Any insight? Thanks.

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  • Database structure for storing Bank-like accounts and transactions

    - by user1241320
    We're in the process of adding a bank-like sub-system to our own shop. We already have customers, so each will be given a sort of account and transactions of some kind will be possible (adding to the account or subtracting from it). So we at least need the account entity, the transaction one and operations will then have to recalculate overall balances. How would you structure your database to handle this? Is there any standard bank system have to use that I could mock? By the way, we're on mysql but will also look at some nosql solution for performance boost.

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  • User control blank on form in VS 2008

    - by Eric
    I've created a user control that contains a table layout control with various other standard controls like buttons and labels. Yet when I add the user control to one of my forms the control is blank. I've tried building the solution and a see the user-control flicker as if it's being updated, but it remains blank. Also if I actually run the program the usercontrol can not be see on the form. I've used usercontrols like this in the past. Is there something I'm missing?

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  • Access Validation Rule Violations on Append Query

    - by Jacques Tardie
    I'm recieving the following error on trying to run an append query in access. Microsoft Office Access set .... and it didnt't add... 779280 records(s) due to validation rule violations. If I choose to run the query anyways, nothing actually happens. To give some context, I'm simply trying to copy a populated field, consisting of values similar to "16-2009-02, 34-2010-02, et cetera" to another currently unpopulated field. The fields themselves have no set validation rules, and both have the standard text field options. I'm hoping to be able to simply remove those hyphens, and fix the issue. But I guess that's what I'm not sure about, are those hyphens actually a problem? Running SP3 w/ Access 2003. Thanks in advance!

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  • Best Practice: Software Versioning

    - by Sebi
    I couldn't find a similar question here on SO, but if you find one please link. Is there any guideline or standard best practice how to version a software you develop in your spare time for fun, but nevertheless will be used by some people? I think it's necessary to version such software so that you know about with version one is talking about (e.g. for bug fixing, support, and so on). But where do I start the versioning? 0.0.0? or 0.0? And then how to I increment the numbers? major release.minor change? and should'nt any commit to a version control system be another version? or is this only for versions which are used in a productive manner?

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  • Style question: Writing "this." before instance variable and methods: good or bad idea?

    - by Uri
    One of my nasty (?) programming habits in C++ and Java is to always precede calls or accesses to members with a this. For example: this.process(this.event). A few of my students commented on this, and I'm wondering if I am teaching bad habits. My rationale is: 1) Makes code more readable — Easier to distinguish fields from local variables. 2) Makes it easier to distinguish standard calls from static calls (especially in Java) 3) Makes me remember that this call (unless the target is final) could end up on a different target, for example in an overriding version in a subclass. Obviously, this has zero impact on the compiled program, it's just readability. So am I making it more or less readable? Related Question Note: I turned it into a CW since there really isn't a correct answer.

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  • Seam app with JBoss 'minimal' Config?

    - by Shadowman
    I'd like to improve the performance of my Seam apps and JBoss appserver, particularly by removing things that aren't necessary in the standard configuration. Ideally, I'd like to be able to run it using the "minimal" profile. Can anyone give me any guidance as to what is needed to run a Seam app using "minimal"? Here are the kind of things my app requires: JPA, using Hibernate with a PostgreSQL backend EJB3 JSF (RichFaces/Facelets) E-mail, eventually, although not required at this particular moment I'll be developing my app using JBoss Tools on Eclipse, so I would also need anything that is required by the tools for development and deployment. I've found that the default configuration just has too many additional components and features installed by default, and that greatly affects performance when I'm trying to develop. Any help you can give would be great! Thanks!

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  • Oracle (Old?) Joins - A tool/script for conversion?

    - by Grasper
    I have been porting oracle selects, and I have been running across a lot of queries like so: SELECT e.last_name, d.department_name FROM employees e, departments d WHERE e.department_id(+) = d.department_id; ...and: SELECT last_name, d.department_id FROM employees e, departments d WHERE e.department_id = d.department_id(+); Are there any guides/tutorials for converting all of the variants of the (+) syntax? What is that syntax even called (so I can scour google)? Even better.. Is there a tool/script that will do this conversion for me (Preferred Free)? An optimizer of some sort? I have around 500 of these queries to port.. When was this standard phased out? Any info is appreciated.

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  • Expression Blend 3 (Silverlight) gives me nothing on project compile

    - by Buginator
    When I press F5 the project compiles, and the new web page launches. However, the silverlight control loads (the standard load counter counts to 100%) but then the whole control just disappear. Only the left default menu bar (feedback etc) is visible. It's a very small project, my first actually. This also happened earlier today, but then I removed each thing one at a time and found that it was some radio buttons that caused it. I deleted them and remade them and it ran fine again. Now the same thing happened again, but it is something else, not sure yet. The question is; is this a familiar bug or am I just doing something wrong? My code-behind consist mostly of visibility changes, around 20 lines of code.

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  • How to declare a function that accepts a lambda?

    - by Andreas Bonini
    I read on the internet many tutorials that explained how to use lambdas with the standard library (such as std::find), and they all were very interesting, but I couldn't find any that explained how I can use a lambda for my own functions. For example: int main() { int test = 5; LambdaTest([&](int a) { test += a; }); return EXIT_SUCCESS; } How should I declare LambdaTest? What's the type of its first argument? And then, how can I call the anonymous function passing to it - for example - "10" as its argument?

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  • Why do I need to explicitly specify all columns in a SQL "GROUP BY" clause - why not "GROUP BY *"?

    - by rwmnau
    This has always bothered me - why does the GROUP BY clause in a SQL statement require that I include all non-aggregate columns? These columns should be included by default - a kind of "GROUP BY *" - since I can't even run the query unless they're all included. Every column has to either be an aggregate or be specified in the "GROUP BY", but it seems like anything not aggregated should be automatically grouped. Maybe it's part of the ANSI-SQL standard, but even so, I don't understand why. Can somebody help me understand the need for this convention?

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  • What's the best way to return a random line in a text file using C?

    - by jeremy Ruten
    What's the best way to return a random line in a text file using C? It has to use the standard I/O library (<stdio.h>) because it's for Nintendo DS homebrew. Clarifications: Using a header in the file to store the number of lines won't work for what I want to do. I want it to be as random as possible (the best being if each line has an equal probability of being chosen as every other line.) The file will never change while the program is being run. (It's the DS, so no multi-tasking.)

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  • Context aware breadcrumbs with php sessions - Will search engines index each variation?

    - by Haroldo
    Some pages on my website appear differently depending on where the user has been, using php sessions. for example with breadcrumbs: standard crumb setup: All Books - fiction - Lord Of the Flies if the visitor has just been on the 'William Golding Page', a session will have been created to say, this visitor is broswing by author, so i would check if( $_SESSION['browsing by] == 'author' ): and the breadcrumbs (for the exact same page as before) would now be: Authors - William Golding - Lord Of the Flies to summarise: So 1 page exists for each book, but depending where the user has come from, the page will show different breadcrumbs. the questions: Can search engines create my 'browsing by' SESSION? Would they index the same page multiple times (for each variation)?

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  • functor returning 0

    - by Jon
    I've recently started teaching myself the standard template library. I was curious as to why the GetTotal() method in this class is returning 0? ... class Count { public: Count() : total(0){} void operator() (int val){ total += val;} int GetTotal() { return total;} private: int total; }; void main() { set<int> s; Count c; for(int i = 0; i < 10; i++) s.inset(i); for_each(s.begin(), s.end(), c); cout << c.GetTotal() << endl; }

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  • Possibility of language data type not mapped to shipped .NET Framework?

    - by John K
    Does anybody know of a managed programming language implemented on .NET that contains a specialized data type that is not mapped through to the Common Type System/FCL/BCL or one that does not have a shipped .NET equivalent (e.g. shipped standard types like System.String, System.Int32)? This question would likely come from the perspective of someone porting a compiler (although I'm not doing that). Is it as simple as the language creating a new data type outside the BCL/FCL for its specialized type? If so does this hinder interoperability between programming languages that are otherwise accustomed to mapping all their built-in data types to what's in the BCL/FCL, like Visual Basic and C#? I can imagine this situation might come about if an obscure language compiler of some kind is ported to .NET for which there is no direct mapping of one of its implicit data types to the shipped Framework. How is this situation supported or allowed in general? What would be the expectation of the compiler and the Common Language Runtime?

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