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• How is the syntax for stl iterators implemented?

  - by Liberalkid

  I've been working on writing a library in my spare time to familiarize myself more with c++ and singular value decomposition. I've been working on writing an Iterator class and I'm entirely capable of writing the functionality and I have already for my own currently MatrixIterator class. I'm guessing that it involves namespaces because: vector<int>::iterator Would appear to be an iterator from the namespace vector, but namespaces are another topic which I'm not familiar with. Mainly I'm asking what would it involve to implement an iterator such that it could be referenced in a similar way to the stl iterators. I'm also aware that I could use boost.iterators or something similar to save myself a lot of work, but I'm more interested in learning all of the details that go into something like this.

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• C# How to place a comma after each word but the last in the list

  - by user576712

  I totally new to C# and learning as I go. I am stuck on issue which I'm hoping an experienced programmer can help. I have added a CheckedListBox to my form and added a collection of 6 items to it. I need all but the last item selected to have a comma placed beside it, so my question is: how can I tell C# NOT to place a comma beside the last item selected? foreach (object itemChecked in RolesCheckedListBox.CheckedItems) { sw.Write(itemChecked.ToString() + ","); } Thanks for any help received! Dan

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• Java Swing UI Changing Method

  - by vigilant

  I would like to use Swing to program a simple learning game. I am wondering what would be best way to switch between UI screens. For example, I would have a screen for the Main Menu, and then when the user presses a button on that screen, I would swap out the whole screen for a completely different one. Then, arbitrary screens can be swapped in at any moment, and all of their event handlers would be reactivated while the inactive screen's event handlers will be deactivated. What type of Swing component/control would I use for each of the 'screens'. Is this even doable?

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• what are most important things that i must know in order to jump into silverlight development

  - by Poni

  I have vast programming knowledge; C++/C#/ActionScript/ASM/PHP..... so learning the language of SilverLight itself isn't of an issue. To keep long story short, when asking this question I'm asking it as a developer who's coming from Flash world - great graphics/sounds/media support, fully cross-platform, ability to combine several SWFs within a "movie" (which also implies code reusability). A Flash developer have pretty much freedom. What are most important things that i must know in order to jump into silverlight development? Did you already make the move to SilverLight from Flash yourself? Are you a "guru" at both? Great, let's hear what you have to say - developer to developer! =)

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• Assistance with regular expressions in Python

  - by da5id

  I am still learning REGEX, and I've run into an issue ... I am trying to separate a string that is composed of a mixture of letters and numbers that are in decimal format: AB0.500CD1.05EF2.29 Into something like this: list1 = AB,CD,EF list2 = 0.500,1.05,2.29 A complication to all this is that I also have strings that look like this: AB1CD2EF3 Which I'd also like to separate into this: list1 = AB,CD,EF list2 = 1,2,3 A previous inquiry yielded the following snippet, import re pattern = re.compile(r'([a-zA-Z]+)([0-9]+)') for (letters, numbers) in re.findall(pattern,cmpnd): print numbers print letters This example works fine for strings of the 2nd kind, but only "finds" the leading digit in the numbers that contain decimal places in the strings of the first kind. I've attempted an approach using the following line: pattern = re.compile(r'([a-zA-Z]+)([0-9]+(\.[0-9]))') But this results in an error: "ValueError: too many values to unpack" Thanks for any and all assistance!

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• C++ Basic Class Layout

  - by Spencer

  Learning C++ and see the class laid out like this: class CRectangle { int x, y; public: void set_values (int,int); int area () {return (x*y);} }; void CRectangle::set_values (int a, int b) { x = a; y = b; } I know Java and methods(functions) in Java are written within the class. The class looks like a Java interface. I know I can write the class like this: class CRectangle { int x, y; public: void set_values (int a, int b) { x = a; y = b; }; int area () {return (x*y);} }; But is there a difference or standard?

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• Errors when using a Ruby On Rails scaffold with a data type of interger

  - by bublebboy

  I am learning Ruby On Rails. I am on a shared hosting with Ruby version 1.8.1 and Rails version 2.3.10. I am working my way through a tutorial at http://railstutorial.org/chapters/a-demo-app?version=2.3#top and at one point in the tutorial it has me run: script/generate scaffold Micropost content:string user_id:interger The tutorial is using the default database, SQLite3. The command works and I use rake db:migrate to create the database. I can view the page listing the microposts (which is empty), but when I try to add a micropost (microposts/new) I get an error undefined method `user_id' for #<Micropost:0x7f710e4988e8> After doing some testing on my own it seems I experience the problem by using the data type of interger. While I understand that using a scaffold is not the best way of building a ruby on rails, I'm just beginning and would still like to know why I am experiencing this problem to help me better understand how rails works.

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• C++0x implementation guesstimates?

  - by dsimcha

  The C++0x standard is on its way to being complete. Until now, I've dabbled in C++, but avoided learning it thoroughly because it seems like it's missing a lot of modern features that I've been spoiled by in other languages. However, I'd be very interested in C++0x, which addresses a lot of my complaints. Any guesstimates, after the standard is ratified, as to how long it will take for major compiler vendors to provide reasonably complete, production-quality implementations? Will it happen soon enough to reverse the decline in C++'s popularity, or is it too little, too late? Do you believe that C++0x will become "the C++" within a few years, or do you believe that most people will stick to the earlier standard in practice and C++0x will be somewhat of a bastard stepchild, kind of like C99?

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• Splitting string to integer from single-line user input?

  - by pootzko

  I just started learning some ruby, and I want to do something like this: print "Insert two numbers: " a, b = gets.split(" ") but I want to make a and b to be integers at the same time (in the same line).. If I add .to_i to the second line (before or after split(" ")), it doesn't work... so, how should I approach this? mapping, splitting, slicing? ok, I know I could use scanf, but other than scanf, how would I do this? sorry for such a noobish question, but I just couldn't find a good enough answer only googling...

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• Do I need to syncronize thread access to an int

  - by Martin Harris

  I've just written a method that is called by multiple threads simultaneously and I need to keep track of when all the threads have completed, the code uses this pattern: private void RunReport() { _reportsRunning++; try { //code to run the report } finally { _reportsRunning--; } } This is the only place within the code that _reportsRunning's value is changed, and the method takes about a second to run. Occasionally when I have more than six or so threads running reports together the final result for _reportsRunning can get down to -1, if I wrap the calls to _runningReports++ and _runningReports-- in a lock then the behaviour appears to be correct and consistant. So, to the question: When I was learning multithreading in C++ I was taught that you didn't need to synchronize calls to increment and decrement operations because they were always one assembly instruction and therefore it was impossible for the thread to be switched out mid-call. Was I taught correctly, and if so how come that doesn't hold true for C#?

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• Creating custom ribbon with SQL Server linked Access application

  - by andy

  I'm just learning about creating custom ribbons in Access 2010, but I'm running into an issue. The Access application I'm working with is connected to a SQL Server backend (connected, not just linked tables). As I understand it, the USysRibbons table needs to exist in the Access application itself, and not in a connected SQL Server. How does one go about creating a table in an Access application that is already linked to a SQL Server? I tried creating the table in a blank database and then importing it into the Access application without any luck.

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• Git: Make one branch exactly like another

  - by G. Martin

  I am relatively new to Git, and I'm still not very comfortable with it. Right now, I'm looking for the command/options/magic that can make the current branch look like another branch; that is, to merge them, but when a conflict arises, to always choose the difference in the branch that is being merged into the current one. My situation is thus; I have an stable(ish) application on the "master" branch. I also have another branch, called "feature". I basically want to make changes/additions/deletions to feature until I like the new feature I'm working on. Once I feel it is ready, I want to make the master branch look identical to the feature branch. I know this probably isn't a best practice, but as I said, I'm new to Git. I plan on learning how to do more complicated things in the future, but for now, this is all I need. Thanks, SO!

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• How many variables is to many when storing in _SESSION?

  - by steve

  Hi - I'm looking for an idea of best practices here. I have a web based application that has a number of hooks into other systems. Let's say 5, and each of these 5 systems has a number of flags to determine different settings the user has selected in said systems, lets say 5 settings per system (so 5*5). I am storing the status of these settings in the user sesion variables and was wondering is that a sufficient way of doing it? I'm learning php as I go along so not sure about any pitfalls that this could run me into!

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• Could someone tell me if my C++ indent style is named? (example given)

  - by Maulrus

  I'm learning C++. For me, my programming style is just what looks the best; it doesn't seem to follow the rules of any one particular style. Here's an example void f(int x){ //no space between close-paren and bracket if (!x){ cout << "x is non-zero\n"; } //closing bracket indented to the same level as the original statement } It's only slightly different for something like a class or a namespace: class myClass {}; //space between class name and bracket, otherwise the same as functions K&R style does uses that kind of bracketing for statements, but my style uses it for everything. I'd like to know if there's a name for it so I can say simply what my indent style is without having to explain using examples like these.

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• Copy a Table's data from a Stored Procedure

  - by Niike2

  I am learning how to use SQL and Stored Procedures. I know the syntax is incorrect: Copy data from one table into another table on another Database with a Stored Procedure. The problem is I don't know what table or what database to copy to. I want it to use parameters and not specify the columns specifically. I have 2 Databases (Master_db and Master_copy) and the same table structure on each DB. I want to quickly select a table in Master_db and copy that table's data into Master_copy table with same name. I have come up with something like this: USE Master_DB CREATE PROCEDURE TransferData DEFINE @tableFrom, @tableTo, @databaseTo; INSERT INTO @databaseTo.dbo.@databaseTo SELECT * FROM Master_DB.dbo.@tableFrom GO;

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• Regular Expression for exclude something that has specific word inside bracked (MySQL)

  - by bn

  This Regular expression if for MySQL query: I want to exclude this row because it has 'something' in side the bracket "bla bla bla bla bla bla (bla bla bla something)" However I want to include this row, because it does not have 'something' inside the bracket "bla bla bla (bla bla bla)" I tried this query but it didnt work. SELECT * FROM table WHERE field NOT REGEXP '((%something%))'; I think this is wrong, I just did trial and error, I like to use regular expression, but never understand it completely. is there any good tutorial/books/links for learning the detail of regular expression? Thank You

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• Query about the service or technology behind gmail service

  - by user1726908

  I am a final year computer science student. I am studying in hyderabad, andhra pradesh, india. I have come to know that the gmail is a cloud service. I am very much interested in learning more about cloud computing. This technology has been puzzling,tickling,increasing my curiosity and i just want to learn as much as i can about it. And through experience, i have learnt that practically doing can improve our knowledge and thirst to learn more. Thus, I would like to know "what are the security measures which you have taken to keep the cloud service like gmail secure and authentic? What is the architecture of the service? What are the technologies used in building it? What are the different levels of security applied in general for building a private cloud?"

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• I can't Distinct, Sum, or Count from 3 tables with group clauses

  - by Rio Inggit Dharmawangsa

  I'm still learning linq, now i'm getting confused. I need data for report from 3 tables, I get the result, but it's duplicate. I have used distinct but it's not working, n I need data to be sum still not working. Here is my query, can somebody explain what's wrong? var report= (from u in myDb.TBL_TRANSAKSI_MKN_MNMs.AsEnumerable() where u.TGL_TRANSAKSI.Value.Date.Equals(dateTimePicker1.Value.Date) join l in myDb.TBL_DETAIL_TRANSAKSIs.AsEnumerable() on u.ID_NOTA equals l.ID_NOTA join m in myDb.TBL_MKN_MNMs.AsEnumerable() on l.ID_MKN_MNM equals m.ID_MKN_MNM group new { u, l, m } by new { m.NAMA_MKN_MNM, m.HARGA_JUAL, u.TGL_TRANSAKSI, l.ID_MKN_MNM, u.USERNAME, l.Jumlah } into grp select new { MakanMinum = grp.Key.NAMA_MKN_MNM, HargaJual = grp.Key.HARGA_JUAL, Stok = grp.Sum(groupedthing => groupedthing.l.Jumlah), Tanggal = grp.Key.TGL_TRANSAKSI, Jumlah =(grp.Key.HARGA_JUAL * grp.Sum(groupedthing => groupedthing.l.Jumlah)), Total = grp.Sum(grouptotal => grp.Key.HARGA_JUAL * grp.Sum(groupedthing => groupedthing.l.Jumlah)), Username = grp.Key.USERNAME }).Distinct();

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• In SQL, a Join is actually an Intersection? And it is also a linkage or a "Sideway Union"?

  - by Jian Lin

  I always thought of a Join in SQL as some kind of linkage between two tables. For example, select e.name, d.name from employees e, departments d where employees.deptID = departments.deptID In this case, it is linking two tables, to show each employee with a department name instead of a department ID. And kind of like a "linkage" or "Union" sideway". But, after learning about inner join vs outer join, it shows that a Join (Inner join) is actually an intersection. For example, when one table has the ID 1, 2, 7, 8, while another table has the ID 7 and 8 only, the way we get the intersection is: select * from t1, t2 where t1.ID = t2.ID to get the two records of "7 and 8". So it is actually an intersection. So we have the "Intersection" of 2 tables. Compare this with the "Union" operation on 2 tables. Can a Join be thought of as an "Intersection"? But what about the "linking" or "sideway union" aspect of it?

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• is counter has certain value inside a class in python

  - by mazlor

  i am learning classes in python and when i was reading the documentation i found this example that i didn't understand : class MyClass: """A simple example class""" def __init__(self): self.data = [] i = 12345 def f(self): return 'hello world' then if we assign : x = MyClass() x.counter = 1 now if we implement while loop : while x.counter < 10: x.counter = x.counter * 2 so the value of x.counter will be : 16 while for example if we have a variable y : y = 1 while y < 1 : y = y *2 then if we look for the value of y we find it 1 so i don't know how is the value of counter became 16 . thanks

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• Designing entire webpages as SVG files

  - by user1311390

  Disclaimer I realize that given the absurdity of the title, this sounds like a troll. However, it's a genuine question. My background involves OpenGL / x86 assembly. I've recently started learning web programming. I really like SVG + CSS, and was wondering -- why do people not design entire webpages in SVG? Context SVG provides beautiful primitive: quadratic + cubic bezier curves; lines + filling -- all as vector graphics SVG provides text SVG provides affine transformations Questions Are there examples of people designing entire websites as a giant SVG file? If not, what the limitations? Are there performance hits when using SVG primitives as opposed to divs/tables?

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• Correct Exceptions in C++

  - by Dr.Ackula

  I am just learning how to handle errors in my C++ code. I wrote this example that looks for a text file called some file, and if its not found will throw an exception. #include <iostream> #include <fstream> using namespace std; int main() { int array[90]; try { ifstream file; file.open("somefile.txt"); if(!file.good()) throw 56; } catch(int e) { cout<<"Error number "<<e<<endl; } return 0; } Now I have two questions. First I would like to know if I am using Exceptions correctly. Second, (assuming the first is true) what is the benefit to using them vs an If else statement?

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• Preparing for the next C++ standard

  - by Neil Butterworth

  The spate of questions regarding BOOST_FOREACH prompts me to ask users of the Boost library what (if anything) they are doing to prepare their code for portability to the proposed new C++ standard (aka C++0x). For example, do you write code like this if you use shared_ptr: #ifdef CPPOX #include <memory> #else #include "boost/shared_ptr.hpp" #endif There is also the namespace issue - in the future, shared_ptr will be part of the std, namespace - how do you deal with that? I'm interested in these questions because I've decided to bite the bullet and start learning boost seriously, and I'd like to use best practices in my code. Not exactly a flood of answers - does this mean it's a non-issue? Anyway, thanks to those that replied; I'm accepting jalfs answer because I like being advised to do nothing!

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• When does code bloat start having a noticeable effect on performance?

  - by Kyle

  I am looking to make a hefty shift towards templates in one of my OpenGL projects, mainly for fun and the learning experience. I plan on watching the size of the executable carefully as I do this, to see just how much of the notorious bloat happens. Currently, the size of my Release build is around 580 KB when I favor speed and 440 KB when I favor size. Yes, it's a tiny project, and in fact even if my executable bloats 10 x its size, it's still going to be 5 MB or so, which hardly seems large by today's standards... or is it? This brings me to my question. Is speed proportional to size, or are there leaps and plateaus at certain thresholds, thresholds which I should be aiming to stay below? (And if so, what are the thresholds specifically?)

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• Comparing Design Patterns

  - by Lijo

  Hi, I am learning design patterns using C#. One of the challenges that I am facing is that they look similar. Could you please help me to distinguish them – basically when to use them? - Why not the other? Bridge and Strategy State and Strategy Façade and Strategy Composite and Strategy I understand that there are lots of resources available in the web. However they does not treat this special question. [Note: I am looking for implementation examples and rationale behind the selection; not mere explanations] It would be great if you are taking examples from any of the following 1) E-Commerce 2) Payroll system 3) Banking 4) Retailing Thanks for your understanding.. Thanks Lijo

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