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• Are QR codes guaranteed to work?

  - by Kiz

  Not sure if this will get closed as "not a real question" but I asked this on Superuser and it was closed for that very reason. We are thinking of implementing a QR code which will be sent to a number of users via an email which links through to a webpage. Now I'm aware that you can just Google 'QR codes' and there are a plethora of options that allow you to make a QR code. My question is thus; if we do go with this solution can we guarantee that it would work cross platform? I.e. on Android, iOS, Symbian etc? Once a QR code is generated will it work on ANY app on ANY platform? Thanks and apologies if this is not really a 'programming question' Thanks Kiran

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• bitshift large strings for encoding QR Codes

  - by icekreaman

  As an example, suppose a QR Code data stream contains 55 data words (each one byte in length) and 15 error correction words (again one byte). The data stream begins with a 12 bit header and ends with four 0 bits. So, 12 + 4 bits of header/footer and 15 bytes of error correction, leaves me 53 bytes to hold 53 alphanumeric characters. The 53 bytes of data and 15 bytes of ec are supplied in a string of length 68 (str68). The problem seems simple enough - concatenate 2 bytes of (right-shifted) header data with str68 and then left shift the entire 70 bytes by 4 bits. This is the first time in many years of programming that I have ever needed to do something like this, I am a c and bit shifting noob, so please be gentle... I have done a little investigation and so far have not been able to figure out how to bitshift 70 bytes of data; any help would be greatly appreciated. Larger QR codes can hold 2000 bytes of data...

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• c arrays: setting size dynamically?

  - by user336994

  Hello, I am new to C programming. I am trying to set the size of the array using a variable but I am getting an error: Storage size of 'array' isn't constant !! 01 int bound = bound*4; 02 static GLubyte vertsArray[bound]; I have noticed that when I replace bounds (within the brackets on line 02) with the number say '20', the program would run with no problems. But I am trying to set the size of the array dynamically ... Any ideas why I am getting this error ? thanks much,

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• iPhone interface design considerations: checkbox and drop-down menu ?

  - by Jesse Armand

  This may not be a programming question, but I don't know where to ask for this and it's still related. We all know that the checkbox and drop-down menu is a UI paradigm brought in from HTML or web interface. I'm not asking for code implementations here. A google search had produced many results. Although if anyone is willing to share that's great. So the question is: Is this a good design approach if we just want to provide a checkbox or drop-down functionality? (e.g. for quizzes, or forms)

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• How do you make Python wait so that you can read the output?

  - by anonnoir

  I've always been a heavy user of Notepad2, as it is fast, feature-rich, and supports syntax highlighting. Recently I've been using it for Python. My problem: when I finish editing a certain Python source code, and try to launch it, the screen disappears before I can see the output pop up. Is there any way for me to make the results wait so that I can read it, short of using an input() or time-delay function? Otherwise I'd have to use IDLE, because of the output that stops for you to read. (My apologies if this question is a silly one, but I'm very new at Python and programming in general.)

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• Bash variable kills script execusion

  - by Kyle Terry

  Sorry if this is better suited at serverfault, but I think it learns more towards the programming side of things. I have some code that's going into /etc/rc.local to detect what type of touch screen monitor is plugged in and changes out the xorg.conf before launching X. Here is a small snippet: CURRENT_MONITOR=`ls /dev/usb | grep 'egalax_touch\|quanta_touch'` case $CURRENT_MONITOR in '') CURRENT_MONITOR='none' ;; esac If one of those two touch screens is plugged in, it works just fine. If any other monitor is plugged in, it stops at the "CURRENT_MONITOR=ls /dev/usb | grep 'egalax_touch\|quanta_touch'." For testing I touched two files. One before creating CURRENT_MONITOR and one after CURRENT_MONITOR and only file touched before is created. I'm not a bash programmer so this might be something very obvious.

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• What webservers have support for HTML5 WebSocket?

  - by Jonas

  I would like to experiment with HTML5 WebSockets, and I am looking for a mature webserver with support for websockets. Is there a list of webservers that support websockets? What popular webservers has support for websockets? The server programming language doesn't matter, I know, Java, PHP, Erlang, Python and more... Just want to do some small experiments. I have looked at a few that doesn't support websockets (yet), i.e. Nginx, Apache and Mochiweb.

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• Write a function in c that includes the following sequence of statements [Wont Compile]

  - by Cody

  There is a question in my programming languages textbook that is as follows: Write a C function that includes the following sequence of statements: x = 21; int x; x = 42; Run the program and explain the results. Rewrite the same code in C++ and Java and compare the results. I have written code, and played with it in all three languages but I can not even get it to compile. This includes declaring x above the three lines as well as in the calling function (as this question is obviously attempting to illustrate scoping issues) I'd like to explain the results and do the comparisons on my own, as it is an assignment question but I was wondering if anyone had any insight as to how to get this code to compile? Thanks

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• iPhone write to file (alternative directory)

  - by strider2k

  New to iPhone 3.2, Apple introduced File-Sharing support. Details can be found at https://developer.apple.com/iphone/library/releasenotes/General/WhatsNewIniPhoneOS/Articles/iPhoneOS3_2.html#//apple_ref/doc/uid/TP40009337-SW1 . Now, most examples floating around in the web demonstrates writing to the documents directory. What if I want to write files from my app but I don't want the user to be able to see it via iTunes? I'm looking at the Files and Networking section of the iPhone OS Programming Guide and I'm unsure what would be a good alternative to the documents directory for writing files to hide from the user and not be rejected by Apple's review team.

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• How to print an isosceles triangle

  - by Steve

  Hello, I'm trying to learn programming by myself, I'm working from a book that has the following problem which I can't solve: Allow the user to input two values: a character to be used for printing an isosceles triangle and the size of the peak for the triangle. For example, if the user inputs # for the character and 6 for the peak, you should produce the following display: # ## ### #### ##### ###### ##### #### ### ## # This is the code I've got so far: char character; int peak; InputValues(out character, out peak); for (int row = 1; row < peak * 2; row++) { for (int col = 1; col <= row; col++) { Console.Write(character); } Console.WriteLine(); } Console.Read() // hold console open Thanks in advance.

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• setNeedsDisplayInRect: paints a white rectangle only

  - by Ion Tichy

  Hi, I'm still a little fresh to CoreGraphics programming, so please bear with me. I'm trying to write an application, which allows the user to rub stuff off an image with the finger. I have the basic functionality nailed down, but the result is sluggish since the screen is redrawn completely every time a touch is rendered. I did some research and found out that I can refresh only a portion of the screen using UIView's setNeedsDisplayInRect: method. This does call drawRect: as expected, however everything I draw in the drawRect: following the setNeedsDisplayInRect: is ignored. Instead, the area in the rect parameter is simply filled with white. No matter what I draw inside, all I end up with is a white rectangle. In essence, this is what I do: 1) when user touches screen, this touch is rendered into a mask 2) when the drawRect: is called, the image is masked with that mask There must be something simple I'm overlooking, surely?

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• How does this Perl grep work to determine the union of several hashes?

  - by titaniumdecoy

  I don't understand the last line of this function from Programming Perl 3e. Here's how you might write a function that does a kind of set intersection by returning a list of keys occurring in all the hashes passed to it: @common = inter( \%foo, \%bar, \%joe ); sub inter { my %seen; for my $href (@_) { while (my $k = each %$href) { $seen{$k}++; } } return grep { $seen{$_} == @_ } keys %seen; } I understand that %seen is a hash which maps each key to the number of times it was encountered in any of the hashes provided to the function.

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• Create and manage child name servers (glue records) within my domain?

  - by basilmir

  Preface I use a top level domain provider that only allows me to add "normal" third-party name servers (a list where i can add "ns1.hostingcompany.com" type entries... nothing else) AND "child name servers" which i can later attach to my parent account ( ns1.myowndomain.com and an ip address). They do not provide other means of linking up. I want to host my own server and dns, even with just one name server (at first). My setup: Airport Extreme - get's a static ip address from my ISP Mac Mini Server - sits behind the Airport and get's a 10.0.1.2 My problem is that i can't seem to configure DNS correctly. I added a "child nameserver" with my airport's external static ip address at the top level provider, so to my understanding i should have all DNS traffic redirected to my Airport. I've opened port 53 UDP to let the traffic in. Now, what i don't get is this. My Mini Server is sitting on a 10.0.1.2 address and i have setup dns correctly, with an A record to point and resolve my server AND a reverse lookup to that 10.0.1.2. So it's ok for "internal stuff". Here is the clicker... How, when a request comes from the exterior for a reverse lookup, does the server "know" ... well look i have everything in 10.0.1.2 but the guy outside needs something from my real address. I can't begin to describe the MX record bonanza... How do i set this "right"? Do i "need" my Mini Server to sit on the external address directly (i can see how this could be the preferred solution, being close to a "real" server i have in my mind). If not... do i need a PTR record on the 10.0.1.2 server but with the external address in there? My dream: I will extend this "setup" with multiple Mini's in different cities where i work. I want a distributed something (Xgrid comes to mind). PS. Be gentle, i've read 2 books and the subject, and bought both the Lynda Essentials and DNS and Networking to boot, still i'm far from being on top of things.

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• If OOP makes problems with large projects, what doesn't?

  - by osca

  I learned Python OOP at school. My (good in theory, bad in practice) informatics told us about how good OOP was for any purpose; Even/Especially for large projects. Now I don't have any experience with teamwork in software development (what a pity, I'd like to program in a team) and I don't know anything about scaling and large projects either. Since some time I'm reading more and more about that object-oriented programming has (many) disadvantages when it comes to really big and important projects/systems. I got a bit confused by that as I always thought that OOP helped you keep large amounts of code clean and structured. Now why should OOP be problematic in large projects? If it is, what would be better? Functional, Declarative/Imperative?

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• Wanting a type of grid for a pixel editor

  - by wiggles

  Hi, I am currently trying to develop a basic pixel editor application to build up my programming experience with Java. I am designing it so the user has several colour options on, they click on an option and then they can drag over the cells in the grid and they change colour (like a typical image editor, but with a sort of snap on to each grid cell) Any idea of what Java component, if any, is able to implement this type of grid in Java? I had thought of each cell being a JButton, but this seemed terribly inefficient and I don't think it would be possible to change the colour of each cell(button) with out individually clicking on each one. Any help appreciated.

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• Bash variable kills script execution

  - by Kyle Terry

  Sorry if this is better suited at serverfault, but I think it learns more towards the programming side of things. I have some code that's going into /etc/rc.local to detect what type of touch screen monitor is plugged in and changes out the xorg.conf before launching X. Here is a small snippet: CURRENT_MONITOR=`ls /dev/usb | grep 'egalax_touch\|quanta_touch'` case $CURRENT_MONITOR in '') CURRENT_MONITOR='none' ;; esac If one of those two touch screens is plugged in, it works just fine. If any other monitor is plugged in, it stops at the "CURRENT_MONITOR=ls /dev/usb | grep 'egalax_touch\|quanta_touch'." For testing I touched two files. One before creating CURRENT_MONITOR and one after CURRENT_MONITOR and only file touched before is created. I'm not a bash programmer so this might be something very obvious.

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• For what programs are Objective C and Ruby ideal on the Mac?

  - by Kurt

  Hi, as a Mac outsider it seems that two popular programming languages on the Mac appear to be Objective C and Ruby. From what I understand the main API Cocoa seems to be written in and optimized for Objective C, but it is also possible to use Ruby for that. Are there different areas where each language is ideal, for example, I could imagine Objective C could be ideal for a GUI layer, or standalone desktop app, and Ruby could be good for web services etc. What about classic business logic, or data access layers? What language would be a good choice for a library of services for example? Can we write a library in one language and link to it from a main program written in the other language? If I wanted to write a layered enterprise application using domain driven design and dependency injection which languages could support each concerns? Are things like DDD and DI common amongst Mac devs? Just a curious outsider.

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• Learning OpenGL ES 1.x

  - by Kristopher Johnson

  What is the quickest way to come up to speed on OpenGL ES 1.x? Let's assume I know nothing about OpenGL (which is not entirely true, but it's been a while since I last used OpenGL). I am most interested in learning this for iPhone-related development, but I'm interested in learning how it works on other platforms as well. I've found the book OpenGL ES 2.0 Programming Guide, but I am concerned that it might not be the best approach because it focuses on 2.0 rather than 1.x. My understanding is that 2.0 is not backwards-compatible with 1.x, so I may miss out on some important concepts. Note: For answers about learning general OpenGL, see http://stackoverflow.com/questions/62540/learning-opengl Some resources I've found: http://khronos.org/opengles/1_X/ http://www.imgtec.com/powervr/insider/sdk/KhronosOpenGLES1xMBX.asp OpenGL Distilled by Paul Martz (a good refresher on OpenGL basics)

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• Repeating a List in Scala

  - by Ralph

  I am a Scala noob. I have decided to write a spider solitaire solver as a first exercise to learn the language and functional programming in general. I would like to generate a randomly shuffled deck of cards containing 1, 2, or 4 suits. Here is what I came up with: val numberOfSuits = 1 (List["clubs", "diamonds", "hearts", "spades"].take(numberOfSuits) * 4).take(4) which should return List["clubs", "clubs", "clubs", "clubs"] List["clubs", "diamonds", "clubs", "diamonds"] List["clubs", "diamonds", "hearts", "spades"] depending on the value of numberOfSuits, except there is no List "multiply" operation that I can find. Did I miss it? Is there a better way to generate the complete deck before shuffling? BTW, I plan on using an Enumeration for the suits, but it was easier to type my question with strings. I will take the List generated above and using a for comprehension, iterate over the suits and a similar List of card "ranks" to generate a complete deck.

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• Build Interactive Floor With Projection !?

  - by Synxmax

  Dear Guys I am somehow newbie and sometimes guru , but at this moment i don't have enough time to research My nightmare is , my boss ask me to create an interactive floor ( he just saw in an exhibition ) , he ask me to create one of them instead of buying , i am an actionscript crawler and developer with some skills in java and c# programming , i just made some track motion with a simple web cam , and this idea came to my mind if i can use an infrared or thermographic camera instead of simple camera so i can get better positioning if camera place at top of floor ! Now i just came here to ask you guys is there any resource , tip , help i can know before getting into this deal !? is there any lib or api out to deal with this ?! EVEN, if there is any resource , article from another language c++ , c , .... could help i just didn't have enough time to test lot of ways If you search interactive floors , or interactive floor projection you can find some companies who provide such a thing Thanks in advance ( and sorry for my damn poor english , français could be better :D )

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• PHP vs JSP Which is should I use/learn for my project?

  - by Jon

  I'm planning on making a fitness planning web application for my senior project at school. However, I don't know anything about either technology and my only experience with web development previously was with python and django. I was wondering what people might recommend to learn, what is most useful to learn for the job market, and what would be best for this project. If it matters, the programming languages I know are, C, C++, Java, and Python. My goal of the project is to learn technologies that will make me a more marketable person. Thanks

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• Python: Data Object or class

  - by arg20

  I enjoy all the python libraries for scraping websites and I am experimenting with BeautifulSoup and IMDB just for fun. As I come from Java, I have some Java-practices incorporated into my programming styles. I am trying to get the info of a certain movie, I can either create a Movie class or just use a dictionary with keys for the attributes. My question is, should I just use dictionaries when a class will only contain data and perhaps almost no behaviour? In other languages creating a type will help you enforce certain restrictions and because of type checks the IDE will help you program, this is not always the case in python, so what should I do? Should I resort to creating a class only when there's both, behaviour and data? Or create a movie class even though it'll probably be just a data container? This all depends on your model, in this particular case either one is fine but I'm wondering about what's a good practice.

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• Animate 3D model programmatically-where to start?

  - by amile

  I am having a task to create a 3D model face that can talk like humans.without having any knowledge about 3D modeling. I have no clue where to start.I have searched a lot and find some of these things.OpenGL,WebGL,XNA and other similar tool can be helpful. please guide me where to start a step by step approach and which platform is better as i have programming background in JAVA. here is an idea what I need to do https://docs.google.com/viewer?a=v&pid=gmail&attid=0.2&thid=13f65486a46a1f67&mt=application/pdf&url=https://mail.google.com/mail/?ui%3D2%26ik%3D49f1f393c6%26view%3Datt%26th%3D13f65486a46a1f67%26attid%3D0.2%26disp%3Dsafe%26realattid%3Df_hi6ylzbv2%26zw&sig=AHIEtbQc8KQNHdprmEnL4UXyD3ox8vlKKQ

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• Unzip a folder which is programatically downloaded in Silverlight

  - by subbu

  Hi all, My requirement is this. I am programmatically downloading a folder from a remote server in zipped format using WebClient. This part is done. My folder will have only DLLs and EXEs. Can any one suggest an unzipping algorithim or libraries which can be used for unzipping? http://www.sharpgis.net/post/2009/04/21/REALLY-small-unzip-utility-for-Silverlight.aspx I tried out the method suggested in the above link. But my DLLs and EXEs are getting corrupted. Can any one help me out in this? My programming environment is VS2010 and Silverlight 4.0. Application is OOB and has Elevated Priv

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• Question about when and when not to raise events (C#)

  - by NoPyGod

  I am programming an instant messaging library for MSN Messenger, and I have a simple question about raising events. When logging in, should I be raising UserAdded for each user that is synchronized (already on the contact list), or should the UserAdded event be reserved for when a new user has been added to the contact list via the AddUser method? Should I perhaps use another event, UserDownloaded for when a user is downloaded? Similarly, when I call logout, should I call UserRemoved? I hope this makes sense. Thank you

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