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• iotop for Linux kernel 2.6.18

  - by Lightsauce

  So it has to come to my attention that iotop isn't availalbe for 2.6.18 since it's less than 2.6.20 and requires Python 2.6+. I've done some research and came across this article: http://lserinol.blogspot.com/2009/09/io-usage-per-process-on-linux.html According to this, if these process have io stats in /proc/pid#/io (where pid# is the process #) it's doable regardless of the kernel version. So, in reality, I could upgrade Python to 2.6 and test out iotop. However, my flavor of Linux, CentOS release 5.5 (Final), only supports Python 2.4.3-44.el5 currently. If I were to do uninstall from yum, it doesn't look so pretty. It ends up wanting to uninstall 235 packages, most of which are very important! I read in one place, online (I forget the URL from yesterday), that you can install Python 2.6+ parallel to this one, and have the rpm install for iotop use that. Well, I didn't choose that route. I figured, what the heck, lets write iotop (not copying it, but reverse engineering it without actually looking at it's code/it in use) in bash. I thought it would just grab the /proc/pid#/io file and parse stats. So I wrote a script to grab the top 10 rchar, wchar, read_bytes, and write_bytes by collecting all these stats from all the /proc/pid#/io files, sorting them by each metric, then grabbing the top 10 highest values. The conclusion, the data seems completely useless. Does anybody know any resources for advanced Linux where I can figure out how to take these /proc/pid#/ directories and figure out what the heck they are doing with io on the disk? My main goal is to figure out what exactly is causing high load on my disk. I just know it's on the / partition (/dev/sda2 in this case), and I'm not really sure how to narrow it down without the help of iotop. If I run iostat to grab metrics for 1 minute, every second, the first result it gives me shows a high 'kB_read/s', so that makes me think, it's reading mostly. However, if I watch the update it gives me every second, it's actually just showing values for kB_wrtn/s. This makes me think the initial value iostat gives me is misleading.

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• Mouse Error Code 24. Windows 7

  - by Cj.

  I've had the same mouse for a while, and it's been working fine until one day, it started giving me a message about a device not working properly. I tried updating the drivers, and re-installing, I even deleted old drivers in case my computer should be a little confused. It never made a difference, and my mouse seemed to be working just fine despite getting the permanent error in my device manager, I looked it up several times online, but I never found anything I could actually use, when I go to official websites, I always get the same response "plug in so so into a different place - drivers - install silverlight before you can watch this tutorial, try it on a different machine". so I gave up on that. But now is where I have a real problem, lately, my little strange error evolved into a fullblown Error 24, and my mouse is starting to turn on and off randomely, especially when it is being used, but I do hear it go "badum..dadum" when I'm off doing something else. when I looked up error code 24, I really didn't find much other than it meaning: Code 24 This device is not present, is not working properly, or does not have all its drivers installed. (Code 24) Cause The device is installed incorrectly. The problem could be a hardware failure, or a new driver might be needed. Devices stay in this state if they have been prepared for removal. After you remove the device, this error disappears. But, I have tried uninstalling the device entirely several times, and it'll go right back to its previous state with error 24, and turning on and off randomely. what do I do? I cannot afford taking it to a repair place, I can't really afford a new mouse either, I refuse to buy cheap ones as I am a gamer, in need of more than 3 buttons, and a good grip is important. Could there possibly be some confusion in the registry? I do remember having gotten some early problems after I converted my vista to windows7. But I hardly dare going in there unless I'm 100% certain of what I'm going for, and I can honestly say I am at a loss here. Edit: it is a USB mouse we're talking about here. MX™518 Optical Gaming Mouse (logitech) Edit2: I am seeing no rupture, so it must be on the inside of my mouse, or inside the rubber, protecting the cable, that would be really inconvenient to search for

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• Resetting root password on Fedora Core 3 - serial cable access only

  - by Sensible Eddie

  A little background: We have an old rackmount server running a customised version of Fedora, manufactured by a company called Navaho. The server is a TeamCAT, running some proprietary rubbish called Freedom2. We have to keep it going - the alternative is extraordinarily expensive, and the business is not likely to be running much longer to justify changing things. Through one means or another, it has fallen upon me to try and resolve our lack of root access. The previous admin has fallen under the proverbial bus, and nobody has any clue. We have no access to the root account for this server. ssh is running on the server, and there is one account admin that we can login with, however it has no permission to do anything (ironic...) The only other way into the server is with a null-modem serial cable. This works... up to a point. I can see the BIOS, I can see the post BIOS screen, and then I see "Starting grub", followed by another screen with about four lines of Linux information, but then it stops at that point. The server continues booting, and all services come online after around two minutes, but the serial terminal displays no more information. I understand it is possible to put Linux into "single user mode" to reset a root password, but I have no idea how to do this beyond trying to interrupt it at the grub stage listed above. When I have tried it just froze. It was almost like grub had appeared (since the server did not continue booting) but I couldn't see it on the serial terminal. Which made me think maybe the grub screen has some different serial settings? I don't know... it's the first time I've ever used serial for access! A friend of mine suggested trying to use a Fedora boot CD. We could boot from USB, so something along this approach is possible but again we still can only see what's going on with the serial terminal, so it might not be achievable. Does anyone have any suggestions for things I can try? I appreciate this is a bit of a long shot, but any assistance would be invaluable. *UPDATE 1 - 28/8/12 * - we will be making some attempts on this today and will post further details later!

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• IE9 Error: There was a pr?blem sending the command to the program

  - by HK1

  I'm working on a new/fresh Windows 7 32bit machine that now has IE9 installed. The user is using the Dell Stardock application as his primary "desktop" (all his links there). When we place an internet link there and click on it we get the following error message: There was a problem sending the command to the program. To me this indicates that IE9 is having trouble going to the website we want to go to, which should get passed as a parameter to the browser when it opens. I don't think this is a StarDock/ObjectDock problem because we also have some other problems with internet links. For example, we cannot move an internet link from the Desktop to the Quick Launch on the task bar. When we do try, it forces us to put the link with the IE icon as part of the IE menu instead of allowing us to have a shortcut there as it's own entry. I should mention however, that links on the desktop and in the taskbar do work as we expect them too (without showing the above error message). It appears that this problem started after installing Windows Updates. Since we installed a whole bunch of updates at once I have no idea which one caused the problem. I did have Google Chrome installed but I uninstalled it since the user wants to use IE. The problem started before I uninstalled Chrome. I also reset the browser settings on IE9. It didn't help. Next I uninstalled IE9 which took me back to IE8. This actually did resolve the problem but the problem came back as soon as I installed IE9 again. We have Verizon Internet Security installed. It's actually a McAfee product rebranded to look like Verizon. I'm not real crazy over this software but the customer has a subscription so we're not planning to change it. I have no reason to believe that this is causing the problem and yet I know that security software is often to blame for strange issues. I've looked at the registry settings for the following keys and everything appears to be ok for every single one of them: HKEY_CLASSES_ROOT\.htm HKEY_CLASSES_ROOT\.html HKEY_CLASSES_ROOT\http\shell\open\command HKEY_CLASSES_ROOT\http\shell\open\ddeexec\Application HKEY_CLASSES_ROOT\https\shell\open\command HKEY_CLASSES_ROOT\https\shell\open\ddeexec\Application HKEY_CLASSES_ROOT\htmlfile\shell\open\command HKEY_CLASSES_ROOT\Microsoft.Website\Shell\Open\Command Edit1: I've found two potential solutions but I won't be able to try them until tomorrow. One is to disable the "Windows Font Cache" service. Another is to clear IE cache and browsing history. I won't be able to try out either solution until tomorrow since this is a remote client's machine. I see there are lots of other suggestions online but if you take the time to read them through you'll see that the other suggestions didn't fix the problem.

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• Can't install .NET framework 4.0 on Windows XP professional version 2002 SP3 (OS bug?)

  - by that guy

  .NET framework 4.0 install fails on Windows XP professional version 2002 SP3: I tried to run setup using "run as..." to make sure the admin rights are used ("protect my computer..." tick was deselected of course). I tried everything: installing using online/offline setup, windows update. install goes a little and then "rolls back" and says: Installation did not succeed .NET Framework 4 has not been installed because: Fatal error during installation. for more information about this problem, see the log file. the full log: http://pastebay.net/1433771 Any ideas? EDIT1: I have found this in the log: "BlockIf: You must install the 32-bit Windows Imaging Component (WIC) before you run Setup. Please visit the Microsoft Download Center to install WIC, and then rerun Setup...." So I found it, and launched "wic_x86_enu.exe" - but it said: WIC Setup error Newer version of update is already on the system. I have already installed: .NET framewrok 2.0 SP2 .NET framewrok 3.0 SP2 .NET framewrok 3.5 SP1 but I need 4.0 . EDIT2: another attempt and it's log. (this time better copy of log file): http://pastebin.com/gmGfbM9a (copy to notepad and save as .htm and open with internet browser). I have tried all the solutions I could find - and nothing helped. I have found something weird: when I formatted the hard drive and installed windows xp again - the .NET framework 4.0 installed ok, but when I plugged my 100Mbit internet cable - the operating system kind off "locked itself" and the bug returned - I could no longer install .NET framework 4.0 again. There was no reason for that to happen, for example I have windows server 2003 in local network, but I don't have active directory enabled on it or anything like that - the server just has some folders shared and thats all (all server's "features" are default). I had the second pc with the same problem - with XP on it too. This seems like the bug of Operating System to me. I couldn't find what was causing the problem. After many days I gave up: backuped everything, formatted HDD and installed Windows 7 professional 64bit. .NET framework 4.0 installed with no problem on it.

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• Need help recovering a corrupt SQL database

  - by user570079

  I have a very special case that I have been working on for several days. I have a very large SQL Server 2008 database (about 2 TB) that contains 500 filegroups to support very large partitioned tables. Recently we had a catastophic failure on one of the drive and lost several filegroups and the database became in-accessible. We have been doing filegroup backups on a daily basis, but due to other issues, we lost our most recent backup of the log and the primary filegroup. We have all the data backed up but the primary filegroup backup is old. There have been no schema changes since the primary filegroup backup, but the lsn's are now all out of sync and we cannot recover the data. I have tried everything I could think of (and have tried just about every trick and hack I could google) but I still end up at the same point where I get messages saying that the files for filegroup x do not match the primary filegroup. I am now at the point of trying to edit the system tables (we have a separate temporary environment to do this so we are not worried about corrupting any production databases). I have tried updated sys.sysdbreg, sys.sysbrickfiles, and sys.sysprufiles to try to trick SQL into thinking all the files are online, but a "Select * From OPENROWSET(TABLE DBPROP, 5)" shows a different database state from what I see in sys.sysdbreg. I am now thinking I need to somehow edit the headers of the actual data files to try to line up the lsn's with the primary. I appreciate any help anyone can give me here, but please do not respond with things like "you are not supposed to do edit mdf, ndf files...." or "see msdn article....", etc. This is an advanced emergency case and I need a real hack so we can just get to the data in this corrupt database and export to a fresh new database. I know there is a way to do this, but not knowing what the DBPROP system functions does (i.e. does it look at system tables or does it actually open the file) is keeping me from trying to figure out how to fool SQL into allowing me to read these files. Thanks for any help.

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• windows 7 virtual wireless adapter keeps going to sleep

  - by conners

  Just a quick question that I can't see mentioned anywhere online. I have a Windows 7 box configured like these guys recommend http://www.itgeekdiary.com/windows-7-as-an-wi-fi-access-point/ simply so that I can have my Windows 7 box as a wifi access point or a wifi emitter. It's also called a Microsoft Virtual WiFi Miniport Adapter. But it powers off and shuts down automatically and stops working. Basically everything works as intended and then - well -it will stopped working when I am not at the Windows 7 PC for a long time. The problem seems to be that every time my PC goes to "power save / sleep" and in the morning the Windows 7 machine "wakes" but blooming heck the wifi has stopped and you have to power cycle the PC (which is very uncool). When I power Cycle I have to do the following as administrator C:\Windows\System32\netsh.exe wlan start hostednetwork I then tried a gazllion things involving services and power management and eventually discovered that if I run the following commands as administrator it will be ok (for a bit) but every 3rd ot 4th time I try this "trick" it simply fails. the trick that seems to work 3 out of 4 times (i.e. "most" of the time) C:\Windows\System32\netsh.exe wlan stop hostednetwork C:\Windows\System32\netsh.exe wlan start hostednetwork But why does this only work "some" of the time? What else I did by myself: on every manage adapter properties (that relates to the wifi) I right clicked [configure] [power management] /disabled/ "allow the computer to power off to save power" <- this made no difference Also (and this is a bit annoying) there is no system tray app/GUI for the Microsoft Virtual WiFi Miniport Adapter output signal ... none... so (lame as it sounds) the ONLY way I can check if it's on is to physically go to another device and SCAN.. lame so my question can probably be solved by any of the following: a) can I stop Windows 7 sleeping this wifi when the machine sleeps b) can I force Windows to force wake this process on wake? if so how? c) what is the service / process REALLY called and how do I restart it if it crashes d) how can I flush the wifi properly rather power cycle the host machine e) anyone have a link to an program or app that can sit in the system tray that shows windows 7 wifi hotspot emission status (on/off/etc etc) Since I am a programmer I can easily write a vbs script / windows exe to fix this (and I will share this solution) and the gui problem if I can work out the actual service that is running that netsh stops/starts

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• FTP script needs blank line

  - by Ones and Zeroes

  I am trying to determine the reason for some FTP servers requiring a blank line in the script as follows: open server.com username ftp_commands bye Refer to blank line required after username credentials. Example from: FTP from batch file another reference to the same: http://newsgroups.derkeiler.com/Archive/Comp/comp.sys.ibm.as400.misc/2008-05/msg00227.html Also discussed here: archive.midrange.com/midrange-l/200601/msg00048.html "The behavior I'm observing is the same as if I didn't specify the password to login." with an answer referring to our same fix... archive.midrange.com/midrange-l/200601/msg00053.html and archive.midrange.com/midrange-l/200601/msg00065.html Note: It is my experience that FTP questions attract uncouth responses. Admittedly FTP is outdated, but many clients still have legacy systems, which they cannot upgrade or replace. The reason thereof should not be discussed here. The intention of this question is to invite a positive response. Please do not respond if you disagree with the above. If you have never encountered this same issue, please do not respond. I suspect this may be limited to FTP scripts executed from Windows machines, but have been told that this happens often and with many different servers. My specific interest is to understand what may cause this as I have a real world example of a production system suddenly requiring this as a workaround fix, after running for many years without issue. The server belongs to a third party who claims no change on their end. Server details unknown and cannot be determined. Any help or encouragement from someone who has come across the same, would be appreciated. ps. Sorry for the many words and references to painful responses, but I have asked similar questions on serverfault and elsewhere and unfortunately got back kneejerk responses to FTP and respondents debating the validity of the question. I would truly not ask, or re-post this question online if I had a better understanding of the issue. I know of people who have seen this issue, but don't know what causes it. I am wary that this question would again turn into another irrelevant discussion. Please, I ask very nicely: Please do not respond if you have not encountered a similar issue. FURTHER EDIT: Please do not suggest changing the product. The problem is not the blank line requirement. We know this fixes the issue. The problem is not being able to explain the reason for the blank line in the first place. Slight difference, but a critical point to note wrt the answering of this question.

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• Windows 7 booting and startup repair issues

  - by aardvark

  I have a MSI FR720 laptop with Windows 7 and Lubuntu partions. For quite a while (6 months or so) I've been having issues booting from my hard drive, it'd take me between 5 minutes and several hours for me to be able to have it recognize the hard drive as a bootable device. I did several disk checks on it, and my hard drive seems in perfect condition, and the fact that booting would usually only work after removing the hard drive and trying to reset it in its slot or lightly shaking it makes me think it had something to do with the connection in the hard drive slot as opposed to the hard drive itself. I was having particular issues with it detecting the hard drive today so I decided to try booting it from an external hard drive dock. It detected it first try and so far has had no problems finding the bootable partitions on my hard drive. When I selected my Windows 7 partition from the boot menu it said that it hadn't been shut down properly last time and needed startup repair. I've done this several times over the last 6 months, so this is hardly unusual. I do startup repair, it fails, and then I try to do a system restore. The system restore also failed, and it says that no files were changed. I restart and try it again. However, this time when I get to the startup repair it's not detecting a Windows OS. I tried clicking next and doing a startup repair but the repair is always failing. If I ignore the startup repair option and instead select "Launch windows normally" it will get to the windows animation, stop halfway through and then crash into a BSoD. I can't read the error on the screen because it immediately switches to back and tries to restart. This is my first time asking a question like this online, so let me know if I need to provide any extra information and I'll do my best to give it I tried using diskpart to find the list of partitions and see if one's labelled as an active partition, but it says that no disk were detected. I can run Lubuntu just fine. I can also see all of my Windows 7 files from it EDIT: The startup repair diagnosis and repair log is this: -- Number of repair attempts: 1 Session details System Disk = Windows directory = AutoChk Run = 0 Number of root causes = 1 Test Performed: Name: Check for updates Result: Completed successfully. Error code = 0x0 Time taken = 15ms Test Performed: Name: System disk test Result: Completed successfully. Error code = 0x0 Time taken = 31ms Root cause found. If a hard disk is installed, it is not responding. -- Any chance that this is a result of me doing this through an external dock through a USB drive?

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• Modern Java alternatives

  - by Ralph

  I'm not sure if stackoverflow is the best forum for this discussion. I have been a Java developer for 14 years and have written an enterprise-level (~500,000 line) Swing application that uses most of the standard library APIs. Recently, I have become disappointed with the progress that the language has made to "modernize" itself, and am looking for an alternative for ongoing development. I have considered moving to the .NET platform, but I have issues with using something the only runs well in Windows (I know about Mono, but that is still far behind Microsoft). I also plan on buying a new Macbook Pro as soon as Apple releases their new rumored Arrandale-based machines and want to develop in an environment that will feel "at home" in Unix/Linux. I have considered using Python or Ruby, but the standard Java library is arguably the largest of any modern language. In JVM-based languages, I looked at Groovy, but am disappointed with its performance. Rumor has it that with the soon-to-be released JDK7, with its InvokeDynamic instruction, this will improve, but I don't know how much. Groovy is also not truly a functional language, although it provides closures and some of the "functional" features on collections. It does not embrace immutability. I have narrowed my search down to two JVM-based alternatives: Scala and Clojure. Each has its strengths and weaknesses. I am looking for the stackoverflow readerships' opinions. I am not an expert at either of these languages; I have read 2 1/2 books on Scala and am currently reading Stu Halloway's book on Clojure. Scala is strongly statically typed. I know the dynamic language folks claim that static typing is a crutch for not doing unit testing, but it does provide a mechanism for compile-time location of a whole class of errors. Scala is more concise than Java, but not as much as Clojure. Scala's inter-operation with Java seems to be better than Clojure's, in that most Java operations are easier to do in Scala than in Clojure. For example, I can find no way in Clojure to create a non-static initialization block in a class derived from a Java superclass. For example, I like the Apache commons CLI library for command line argument parsing. In Java and Scala, I can create a new Options object and add Option items to it in an initialization block as follows (Java code): final Options options = new Options() { { addOption(new Option("?", "help", false, "Show this usage information"); // other options } }; I can't figure out how to the same thing in Clojure (except by using (doit...)), although that may reflect my lack of knowledge of the language. Clojure's collections are optimized for immutability. They rarely require copy-on-write semantics. I don't know if Scala's immutable collections are implemented using similar algorithms, but Rich Hickey (Clojure's inventor) goes out of his way to explain how that language's data structures are efficient. Clojure was designed from the beginning for concurrency (as was Scala) and with modern multi-core processors, concurrency takes on more importance, but I occasionally need to write simple non-concurrent utilities, and Scala code probably runs a little faster for these applications since it discourages, but does not prohibit, "simple" mutability. One could argue that one-off utilities do not have to be super-fast, but sometimes they do tasks that take hours or days to complete. I know that there is no right answer to this "question", but I thought I would open it up for discussion. If anyone has a suggestion for another JVM-based language that can be used for enterprise level development, please list it. Also, it is not my intent to start a flame war. Thanks, Ralph

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• Interactive Data Language, IDL: Does anybody care?

  - by Alex

  Anyone use a language called Interactive Data Language, IDL? It is popular with scientists. I think it is a poor language because it is proprietary (every terminal running it has to have an expensive license purchased) and it has minimal support (try searching for IDL, the language, right now on stack) . I am trying to convince my colleagues to stop using it and learn C/C++/Python/Fortran/Java/Ruby. Does anybody know about or even care about IDL enough to have opinions on it? What do you think of it? Should I tell my colleagues to stop wasting their time on it now? How can I convince them? Edit: People are getting the impression that I don't know or use IDL. Also, I said IDL has minimal support which is true in one sense, so I must clarify that the scientific libraries are indeed large. I use IDL all the time, but this is exactly the problem: I am only using IDL because colleagues use it. There is a file format IDL uses, the .sav, which can only be opened in IDL. So I must use IDL to work with this data and transfer the data back to colleagues, but I know I would be more efficient in another language. This is like someone sending you a microsoft word file in an email attachment and if you don't understand how wrong that is then you probably write too many words not enough code and you bought microsoft word. Edit: As an alternative to IDL Python is popular. Here is a list of The Pros of IDL (and the cons) from AstroBetter: Pros of IDL Mature many numerical and astronomical libraries available Wide astronomical user base Numerical aspect well integrated with language itself Many local users with deep experience Faster for small arrays Easier installation Good, unified documentation Standard GUI run/debug tool (IDLDE) Single widget system (no angst about which to choose or learn) SAVE/RESTORE capability Use of keyword arguments as flags more convenient Cons of IDL Narrow applicability, not well suited to general programming Slower for large arrays Array functionality less powerful Table support poor Limited ability to extend using C or Fortran, such extensions hard to distribute and support Expensive, sometimes problem collaborating with others that don’t have or can’t afford licenses. Closed source (only RSI can fix bugs) Very awkward to integrate with IRAF tasks Memory management more awkward Single widget system (useless if working within another framework) Plotting: Awkward support for symbols and math text Many font systems, portability issues (v5.1 alleviates somewhat) not as flexible or as extensible plot windows not intrinsically interactive (e.g., pan & zoom) Pros of Python Very general and powerful programming language, yet easy to learn. Strong, but optional, Object Oriented programming support Very large user and developer community, very extensive and broad library base Very extensible with C, C++, or Fortran, portable distribution mechanisms available Free; non-restrictive license; Open Source Becoming the standard scripting language for astronomy Easy to use with IRAF tasks Basis of STScI application efforts More general array capabilities Faster for large arrays, better support for memory mapping Many books and on-line documentation resources available (for the language and its libraries) Better support for table structures Plotting framework (matplotlib) more extensible and general Better font support and portability (only one way to do it too) Usable within many windowing frameworks (GTK, Tk, WX, Qt…) Standard plotting functionality independent of framework used plots are embeddable within other GUIs more powerful image handling (multiple simultaneous LUTS, optional resampling/rescaling, alpha blending, etc) Support for many widget systems Strong local influence over capabilities being developed for Python Cons of Python More items to install separately Not as well accepted in astronomical community (but support clearly growing) Scientific libraries not as mature: Documentation not as complete, not as unified Not as deep in astronomical libraries and utilities Not all IDL numerical library functions have corresponding functionality in Python Some numeric constructs not quite as consistent with language (or slightly less convenient than IDL) Array indexing convention “backwards” Small array performance slower No standard GUI run/debug tool Support for many widget systems (angst regarding which to choose) Current lack of function equivalent to SAVE/RESTORE in IDL matplotlib does not yet have equivalents for all IDL 2-D plotting capability (e.g., surface plots) Use of keyword arguments used as flags less convenient Plotting: comparatively immature, still much development going on missing some plot type (e.g., surface) 3-d capability requires VTK (though matplotlib has some basic 3-d capability)

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• Scope quandary with namespaces, function templates, and static data

  - by Adrian McCarthy

  This scoping problem seems like the type of C++ quandary that Scott Meyers would have addressed in one of his Effective C++ books. I have a function, Analyze, that does some analysis on a range of data. The function is called from a few places with different types of iterators, so I have made it a template (and thus implemented it in a header file). The function depends on a static table of data, AnalysisTable, that I don't want to expose to the rest of the code. My first approach was to make the table a static const inside Analysis. namespace MyNamespace { template <typename InputIterator> int Analyze(InputIterator begin, InputIterator end) { static const int AnalysisTable[] = { /* data */ }; ... // implementation uses AnalysisTable return result; } } // namespace MyNamespace It appears that the compiler creates a copy of AnalysisTable for each instantiation of Analyze, which is wasteful of space (and, to a small degree, time). So I moved the table outside the function like this: namespace MyNamespace { const int AnalysisTable[] = { /* data */ }; template <typename InputIterator> int Analyze(InputIterator begin, InputIterator end) { ... // implementation uses AnalysisTable return result; } } // namespace MyNamespace There's only one copy of the table now, but it's exposed to the rest of the code. I'd rather keep this implementation detail hidden, so I introduced an unnamed namespace: namespace MyNamespace { namespace { // unnamed to hide AnalysisTable const int AnalysisTable[] = { /* data */ }; } // unnamed namespace template <typename InputIterator> int Analyze(InputIterator begin, InputIterator end) { ... // implementation uses AnalysisTable return result; } } // namespace MyNamespace But now I again have multiple copies of the table, because each compilation unit that includes this header file gets its own. If Analyze weren't a template, I could move all the implementation detail out of the header file. But it is a template, so I seem stuck. My next attempt was to put the table in the implementation file and to make an extern declaration within Analyze. // foo.h ------ namespace MyNamespace { template <typename InputIterator> int Analyze(InputIterator begin, InputIterator end) { extern const int AnalysisTable[]; ... // implementation uses AnalysisTable return result; } } // namespace MyNamespace // foo.cpp ------ #include "foo.h" namespace MyNamespace { const int AnalysisTable[] = { /* data */ }; } This looks like it should work, and--indeed--the compiler is satisfied. The linker, however, complains, "unresolved external symbol AnalysisTable." Drat! (Can someone explain what I'm missing here?) The only thing I could think of was to give the inner namespace a name, declare the table in the header, and provide the actual data in an implementation file: // foo.h ----- namespace MyNamespace { namespace PrivateStuff { extern const int AnalysisTable[]; } // unnamed namespace template <typename InputIterator> int Analyze(InputIterator begin, InputIterator end) { ... // implementation uses PrivateStuff::AnalysisTable return result; } } // namespace MyNamespace // foo.cpp ----- #include "foo.h" namespace MyNamespace { namespace PrivateStuff { const int AnalysisTable[] = { /* data */ }; } } Once again, I have exactly one instance of AnalysisTable (yay!), but other parts of the program can access it (boo!). The inner namespace makes it a little clearer that they shouldn't, but it's still possible. Is it possible to have one instance of the table and to move the table beyond the reach of everything but Analyze?

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• Unresolved compilation problems -- can't use .jar files that I have created

  - by Mike

  I created a few .jar files and am trying to access them in another application - I have tried to use both Eclipse and IntelliJ and experience the same issue: java.lang.Error: Unresolved compilation problems: The import com.XXXX.XXXXXXXXX.project2 cannot be resolved The import com.XXXX.XXXXXXXXX.project2 cannot be resolved BeanFactory cannot be resolved to a type Author cannot be resolved to a type AuthorFactoryImpl cannot be resolved to a type Author cannot be resolved to a type Author cannot be resolved to a type I have been using Maven during this process and the jars compile fine. I have included them on the file path using both the Maven .pom file and directly assigning them. I also have unassigned the direct file path and left the reference in Maven and vise versa -- no difference. See below .jar file class info: file structure: Author.java BeanWithIdentityInterface Books Subject ie: Interface: package com.XXXX.training; /** * Created with IntelliJ IDEA. * User: kBPersonal * Date: 11/5/12 * Time: 3:16 PM * */ public interface BeanWithIdentityInterface <I> { I getId(); } Author.java: package com.XXXX.training; /** * Created with IntelliJ IDEA. * User: kBPersonal * Date: 10/25/12 * Time: 12:03 PM */ public class Author implements BeanWithIdentityInterface <Integer>{ private Integer id = null; private String name = null; private String picture = null; private String bio = null; public Author(Integer id, String bio, String name, String picture) { this.id = id; this.bio = bio; this.name = name; this.picture = picture; } public Author (){} @Override public Integer getId() { return id; } public void setId(Integer id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } public String getPicture() { return picture; } public void setPicture(String picture) { this.picture = picture; } public String getBio() { return bio; } public void setBio(String bio) { this.bio = bio; } @Override public String toString() { return "\n\tAuthor Id: "+this.getId() + " | Bio:"+ this.getBio()+ " | Name:"+ this.getName()+ " | Picture: "+ this.getPicture(); } } implementing Servlet: package com.acentia.training.project3.controller; import com.acentia.training.*; import com.acentia.training.project2.AuthorFactoryImpl; import com.acentia.training.project2.BeanFactory; import javax.servlet.ServletException; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import java.io.IOException; import java.io.PrintWriter; /** * Created with IntelliJ IDEA. * User: kBPersonal * Date: 11/11/12 * Time: 6:34 PM * */ public class ListAuthorServlet extends AbstractBaseServlet { private static final long serialVersionUID = -6934109551750492182L; public void doProcess(final HttpServletRequest request, final HttpServletResponse response) throws IOException { final BeanFactory<Author, Integer> authorFactory = new AuthorFactoryImpl(); Author author = null; if (authorFactory != null) { author = (Author) authorFactory.getMember(5); } I can't pull the Author class. Any help would be greatly appreciated.

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• The best cross platform (portable) arbitrary precision math library

  - by Siu Ching Pong - Asuka Kenji

  Dear ninjas / hackers / wizards, I'm looking for a good arbitrary precision math library in C or C++. Could you please give me some advices / suggestions? The primary requirements: It MUST handle arbitrarily big integers (my primary interest is on integers). In case that you don't know what the word arbitrarily big means, imagine something like 100000! (the factorial of 100000). The precision MUST NOT NEED to be specified during library initialization / object creation. The precision should ONLY be constrained by the available resources of the system. It SHOULD utilize the full power of the platform, and should handle "small" numbers natively. That means on a 64-bit platform, calculating 2^33 + 2^32 should use the available 64-bit CPU instructions. The library SHOULD NOT calculate this in the same way as it does with 2^66 + 2^65 on the same platform. It MUST handle addition (+), subtraction (-), multiplication (*), integer division (/), remainder (%), power (**), increment (++), decrement (--), gcd(), factorial(), and other common integer arithmetic calculations efficiently. Ability to handle functions like sqrt() (square root), log() (logarithm) that do not produce integer results is a plus. Ability to handle symbolic computations is even better. Here are what I found so far: Java's BigInteger and BigDecimal class: I have been using these so far. I have read the source code, but I don't understand the math underneath. It may be based on theories / algorithms that I have never learnt. The built-in integer type or in core libraries of bc / Python / Ruby / Haskell / Lisp / Erlang / OCaml / PHP / some other languages: I have ever used some of these, but I have no idea on which library they are using, or which kind of implementation they are using. What I have already known: Using a char as a decimal digit, and a char* as a decimal string and do calculations on the digits using a for-loop. Using an int (or a long int, or a long long) as a basic "unit" and an array of it as an arbitrary long integer, and do calculations on the elements using a for-loop. Booth's multiplication algorithm What I don't know: Printing the binary array mentioned above in decimal without using naive methods. Example of a naive method: (1) add the bits from the lowest to the highest: 1, 2, 4, 8, 16, 32, ... (2) use a char* string mentioned above to store the intermediate decimal results). What I appreciate: Good comparisons on GMP, MPFR, decNumber (or other libraries that are good in your opinion). Good suggestions on books / articles that I should read. For example, an illustration with figures on how a un-naive arbitrarily long binary to decimal conversion algorithm works is good. Any help. Please DO NOT answer this question if: you think using a double (or a long double, or a long long double) can solve this problem easily. If you do think so, it means that you don't understand the issue under discussion. you have no experience on arbitrary precision mathematics. Thank you in advance! Asuka Kenji

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• How do I explain this to potential employers?

  - by ReferencelessBob

  Backstory: TL;DR: I've gained a lot of experience working for 5 years at one startup company, but it eventually failed. The company is gone and the owner MIA. When I left sixth-form college I didn't want to start a degree straight away, so when I met this guy who knew a guy who was setting up a publishing company and needed a 'Techie' I thought why not. It was a very small operation, he sent mailings to schools, waited for orders to start arriving, then ordered a short run of the textbooks to be printed, stuck them in an envelope posted them out. I was initially going to help him set up a computerized system for recording orders and payments, printing labels, really basic stuff and I threw it together in Access in a couple of weeks. He also wanted to start taking orders online, so I set up a website and a paypal business account. While I was doing this, I was also helping to do the day-to-day running of things, taking phone orders, posting products, banking cheques, ordering textbooks, designing mailings, filing end of year accounts, hiring extra staff, putting stamps on envelopes. I learned so much about things I didn't even know I needed to learn about. Things were pretty good, when I started we sold about £10,000 worth of textbooks and by my 4th year there we sold £250,000 worth of text books. Things were looking good, but we had a problem. Our best selling product had peaked and sales started to fall sharply, we introduced add on products through the website to boost sales which helped for a while, but we had simply saturated the market. Our plan was to enter the US with our star product and follow the same, slightly modified, plan as before. We setup a 1-866 number and had the calls forwarded to our UK offices. We contracted a fulfillment company, shipped over a few thousand textbooks, had a mailing printed and mailed, then sat by the phones and waited. Needless to say, it didn't work. We tried a few other things, at home and in the US, but nothing helped. We expanded in the good times, moving into bigger offices, taking on staff to do administrative and dispatch work, but now cashflow was becoming a problem and things got tougher. We did the only thing we could and scaled things right back, the offices went, the admin staff went, I stopped taking a wage and started working from home. Nothing helped. The business was wound up about about 2 years ago. In the end it turned out that the owner had built up considerable debt at the start of business and had not paid them off during good years, which left him in a difficult position when cashflow had started to dry up. I haven't been able to contact the owner since I found out. It took me a while to get back on my feet after that, but I'm now at University and doing a Computer Science degree. How do I show the experience I have without having to get into all the gory details of what happened?

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• Generate JFreeChart in servlet

  - by San4o

  I'm trying to generate graphs using JFreeChart. I added record in web.xml, installed jfreechart library. Compiled servlet. Below code of servlet has shown: import java.io.IOException; import java.io.OutputStream; import java.io.File; import javax.servlet.*; import javax.servlet.http.*; import java.awt.Color; import org.jfree.chart.ChartFactory; import org.jfree.chart.ChartUtilities; import org.jfree.chart.JFreeChart; import org.jfree.data.general.DefaultPieDataset; public class diagram extends HttpServlet { public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doTestPieChart(request,response); } protected void doTestPieChart(HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException { OutputStream out = response.getOutputStream(); try { DefaultPieDataset dataset = new DefaultPieDataset(); dataset.setValue("Graphic Novels", 192); dataset.setValue("History", 125); dataset.setValue("Military Fiction", 236); dataset.setValue("Mystery", 547); dataset.setValue("Performing Arts", 210); dataset.setValue("Science, Non-Fiction", 70); dataset.setValue("Science Fiction", 989); JFreeChart chart = ChartFactory.createPieChart( "Books by Type", dataset, true, false, false ); chart.setBackgroundPaint(Color.white); response.setContentType("image/png"); ChartUtilities.writeChartAsPNG(out, chart, 400, 300); /* ServletContext sc = getServletContext(); String filename = sc.getRealPath("pie.png"); File file = new File(filename); ChartUtilities.saveChartAsPNG(file,chart,400,300); */ } catch (Exception e) { System.out.println(e.toString()); } finally { out.close(); } } } When i launch the servlet, mistake has shown : HTTP Status 500 - type Exception report message description The server encountered an internal error () that prevented it from fulfilling this request. exception javax.servlet.ServletException: Error instantiating servlet class diagram org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102) org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:298) org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:852) org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:588) org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489) java.lang.Thread.run(Thread.java:619) root cause java.lang.NoClassDefFoundError: org/jfree/data/general/PieDataset java.lang.Class.getDeclaredConstructors0(Native Method) java.lang.Class.privateGetDeclaredConstructors(Class.java:2389) java.lang.Class.getConstructor0(Class.java:2699) java.lang.Class.newInstance0(Class.java:326) java.lang.Class.newInstance(Class.java:308) org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102) org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:298) org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:852) org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:588) org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489) java.lang.Thread.run(Thread.java:619) root cause java.lang.ClassNotFoundException: org.jfree.data.general.PieDataset org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1484) org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1329) java.lang.ClassLoader.loadClassInternal(ClassLoader.java:316) java.lang.Class.getDeclaredConstructors0(Native Method) java.lang.Class.privateGetDeclaredConstructors(Class.java:2389) java.lang.Class.getConstructor0(Class.java:2699) java.lang.Class.newInstance0(Class.java:326) java.lang.Class.newInstance(Class.java:308) org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102) org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:298) org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:852) org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:588) org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489) java.lang.Thread.run(Thread.java:619) note The full stack trace of the root cause is available in the Apache Tomcat/6.0.24 logs. Help me to solve a problem. and where is problem?

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• JFrame not working correctly

  - by Nick Gibson

  This is making me very angry, I have worked on this for 2 days, have 2 books open and have looked through them, and STILL can't get this program to run the way I want it run. I'm getting to the point where if this doesn't help, I quit. I want a SIMPLE Frame application. It has a JComboBox centered at the top. Next to it is a text field big enough to show numeric digits such as "$49.99" Below it is a spot for a Text area showing terms of service Below that is the checkbox agreeing to the terms of service Below that is 2 buttons "Accept" and "Decline" I Have worked on this for 2 days, here is the coding: public class Bar extends JFrame implements ActionListener { public Bar(final JFrame frame) { String[] tests = { "A+ Certification", "Network+ Certification", "Security+ Certification", "CIT Full Test Package" }; JButton button = new JButton("Click Meh"); add(new JLabel("Welcome to the CIT Test Program ")); add(new JLabel("Please select which Test Package from the list below.")); frame.setVisible(true); frame.setSize(250,250); JPanel pane1 = new JPanel(new FlowLayout()); JPanel pane2 = new JPanel(new FlowLayout()); JMenuBar menuBar = new JMenuBar(); JMenu fileMenu = new JMenu("File"); JMenu editMenu = new JMenu("Edit"); JMenu helpMenu = new JMenu("Help"); menuBar.add(fileMenu); menuBar.add(editMenu); menuBar.add(helpMenu); JMenuItem newMenu = new JMenuItem("New (Ctrl+N)"); JMenuItem openMenu = new JMenuItem("Open (Ctrl+O)"); JMenuItem saveMenu = new JMenuItem("Save (Ctrl+S)"); saveMenu.addActionListener(this); JMenuItem exitMenu = new JMenuItem("Exit (Ctrl+W)"); JMenuItem cutMenu = new JMenuItem("Cut (Ctrl+X)"); JMenuItem copyMenu = new JMenuItem("Copy (Ctrl+C)"); JMenuItem pasteMenu = new JMenuItem("Paste (Ctrl+V)"); JMenuItem infoMenu = new JMenuItem("Help (Ctrl+H)"); fileMenu.add(newMenu); fileMenu.add(openMenu); fileMenu.add(saveMenu); fileMenu.add(exitMenu); editMenu.add(cutMenu); editMenu.add(copyMenu); editMenu.add(pasteMenu); helpMenu.add(infoMenu); frame.setJMenuBar(menuBar); JComboBox packageChoice = new JComboBox(tests); frame.add(packageChoice); } public void actionPerformed(ActionEvent e) { Object source = e.getSource(); { } } EDIT: Forgot to add the second program public class JFrameWithPanel { public static void main(String[] args) { JPanel panel = new Bar(new JFrame("CIT Test Program")); } } How do I get this to have everything where I want it and show up? I'm very confused because of this and now barely even get how Frames work.

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• How color attributes work in VBO?

  - by Jayesh

  I am coding to OpenGL ES 2.0 (Webgl). I am using VBOs to draw primitives. I have vertex array, color array and array of indices. I have looked at sample codes, books and tutorial, but one thing I don't get - if color is defined per vertex how does it affect the polygonal surfaces adjacent to those vertices? (I am a newbie to OpenGL(ES)) I will explain with an example. I have a cube to draw. From what I read in OpenGLES book, the color is defined as an vertex attribute. In that case, if I want to draw 6 faces of the cube with 6 different colors how should I define the colors. The source of my confusion is: each vertex is common to 3 faces, then how will it help defining a color per vertex? (Or should the color be defined per index?). The fact that we need to subdivide these faces into triangles, makes it harder for me to understand how this relationship works. The same confusion goes for edges. Instead of drawing triangles, let's say I want to draw edges using LINES primitives. Each edge of different color. How am I supposed to define color attributes in that case? I have seen few working examples. Specifically this tutorial: http://learningwebgl.com/blog/?p=370 I see how color array is defined in the above example to draw a cube with 6 different colored faces, but I don't understand why is defined that way. (Why is each color copied 4 times into unpackedColors for instance?) Can someone explain how color attributes work in VBO? [The link above seems inaccessible, so I will post the relevant code here] cubeVertexPositionBuffer = gl.createBuffer(); gl.bindBuffer(gl.ARRAY_BUFFER, cubeVertexPositionBuffer); vertices = [ // Front face -1.0, -1.0, 1.0, 1.0, -1.0, 1.0, 1.0, 1.0, 1.0, -1.0, 1.0, 1.0, // Back face -1.0, -1.0, -1.0, -1.0, 1.0, -1.0, 1.0, 1.0, -1.0, 1.0, -1.0, -1.0, // Top face -1.0, 1.0, -1.0, -1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, -1.0, // Bottom face -1.0, -1.0, -1.0, 1.0, -1.0, -1.0, 1.0, -1.0, 1.0, -1.0, -1.0, 1.0, // Right face 1.0, -1.0, -1.0, 1.0, 1.0, -1.0, 1.0, 1.0, 1.0, 1.0, -1.0, 1.0, // Left face -1.0, -1.0, -1.0, -1.0, -1.0, 1.0, -1.0, 1.0, 1.0, -1.0, 1.0, -1.0, ]; gl.bufferData(gl.ARRAY_BUFFER, new WebGLFloatArray(vertices), gl.STATIC_DRAW); cubeVertexPositionBuffer.itemSize = 3; cubeVertexPositionBuffer.numItems = 24; cubeVertexColorBuffer = gl.createBuffer(); gl.bindBuffer(gl.ARRAY_BUFFER, cubeVertexColorBuffer); var colors = [ [1.0, 0.0, 0.0, 1.0], // Front face [1.0, 1.0, 0.0, 1.0], // Back face [0.0, 1.0, 0.0, 1.0], // Top face [1.0, 0.5, 0.5, 1.0], // Bottom face [1.0, 0.0, 1.0, 1.0], // Right face [0.0, 0.0, 1.0, 1.0], // Left face ]; var unpackedColors = [] for (var i in colors) { var color = colors[i]; for (var j=0; j < 4; j++) { unpackedColors = unpackedColors.concat(color); } } gl.bufferData(gl.ARRAY_BUFFER, new WebGLFloatArray(unpackedColors), gl.STATIC_DRAW); cubeVertexColorBuffer.itemSize = 4; cubeVertexColorBuffer.numItems = 24; cubeVertexIndexBuffer = gl.createBuffer(); gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, cubeVertexIndexBuffer); var cubeVertexIndices = [ 0, 1, 2, 0, 2, 3, // Front face 4, 5, 6, 4, 6, 7, // Back face 8, 9, 10, 8, 10, 11, // Top face 12, 13, 14, 12, 14, 15, // Bottom face 16, 17, 18, 16, 18, 19, // Right face 20, 21, 22, 20, 22, 23 // Left face ] gl.bufferData(gl.ELEMENT_ARRAY_BUFFER, new WebGLUnsignedShortArray(cubeVertexIndices), gl.STATIC_DRAW); cubeVertexIndexBuffer.itemSize = 1; cubeVertexIndexBuffer.numItems = 36;

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• Linked list in C

  - by ScReYm0

  I am still new at lists in C and i got a big problem... First i wanna show you my code for inserting item to the list: void input_books_info(int number_of_books, BOOK *current) { int i; for(i = 0; i < number_of_books; i++) { while(current->next != NULL) current = current->next; current->next = (BOOK *)malloc(sizeof(BOOK)); printf_s("%d book catalog number: ", i + 1); scanf_s("%s", &current->next->catalog_number , 20); printf_s("%d book title: ", i + 1); scanf_s("%s", current->next->title ,80); printf_s("%d book author: ", i + 1); scanf_s("%s", current->next->author ,40); printf_s("%d book publisher: ", i+1); scanf_s("%s", current->next->publisher,80); printf_s("%d book price: ", i + 1); scanf_s("%f", &current->next->price, 5); printf_s("%d book year published: ", i + 1); scanf_s("%d", &current->next->year_published, 5); current->next->next = NULL; printf_s("\n\n"); } } And this is my main function: void main (void) { int number_of_books, t = 1; char book_catalog_number[STRMAX]; char book_title[STRMAX]; char book_author[STRMAX]; char reading_file[STRMAX]; char saving_file[STRMAX]; first = malloc(sizeof(BOOK)); first->next = NULL; /* printf_s("Enter file name: "); gets(saving_file); first->next = book_open(first, saving_file); */ while(t) { char m; printf_s("1. Input \n0. Exit \n\n"); printf_s("Choose operation: "); m = getch(); switch(m) { case '1': printf_s("\ninput number of books: "); scanf_s("%d", &number_of_books); input_books_info(number_of_books, first); printf_s("\n"); break; default: printf_s("\nNo entry found!\n\n\n\n\n"); break; } } } and last maybe here is the problem the printing function: void print_books_info(BOOK *current) { while(current->next != NULL && current != NULL) { printf_s("%s, ", current->next->catalog_number); printf_s("%s, ", current->author); printf_s("%s, ", current->next->title); printf_s("%s, ", current->next->author); printf_s("%s, ", current->next->publisher); printf_s("%.2f, ", current->next->price); printf_s("%d", current->next->year_published); printf_s("\n\n"); current = current->next; } } And my problem is that, when i run the app, program is moving good. But when I start the app, the program is storing only first input of data second and third are lost ... Can you help me to figure out it... ???

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• Multidimensional array problem in VHDL?

  - by Nektarios

  I'm trying to use a multidimensional array in VHDL and I'm having a lot of trouble getting it to work properly. My issue is that I've got an array of 17, of 16 vectors, of a given size. What I want to do is create 17 registers that are array of 16 * std_logic_vector of 32 bits (which = my b, 512). So, I'm trying to pass in something to input and output on the register instantiation that tells the compiler/synthesizer that I want to pass in something that is 512 bits worth... Similar to in C if I had: int var[COLS][ROWS][ELEMENTS]; memcpy(&var[3].. // I'm talking about 3rd COL here, passing in memory that is ROWS*ELEMENTS long (My actual declaration is here:) type partial_pipeline_registers_type is array (0 to 16, 0 to 15) of std_logic_vector(iw - 1 downto 0); signal h_blk_pipelined_input : partial_pipeline_registers_type; I tried simply using h_blk_pipelined_input(0) .. up to (16) but this doesn't work. I get the following error, which makes me see that I need to double index in to the array: ERROR:HDLParsers:821 - (at the register) Wrong index type for h_blk_pipelined_input. So then I tried what's below, and I get this error: ERROR:HDLParsers:164 - (at the register code). parse error, unexpected TO, expecting COMMA or CLOSEPAR instantiate_h_pipelined_reg : regn generic map ( N=> b, init => bzeros ) port map ( clk => clk , rst => '0', en => '1', input => h_blk_pipelined_input((i - 1), 0 to 15), output=> h_blk_pipelined_input((i), 0 to 15)); -- Changing 0 to 15 to (0 to 15) has no effect... I'm using XST, and from their documentation (http://www.xilinx.com/itp/xilinx6/books/data/docs/xst/xst0067_9.html), the above should have worked: ...declaration: subtype MATRIX15 is array(4 downto 0, 2 downto 0) of STD_LOGIC_VECTOR (7 downto 0); A multi-dimensional array signal or variable can be completely used: Just a slice of one row can be specified: MATRIX15 (4,4 downto 1) <= TAB_B (3 downto 0); One alternative is that I can create more registers that are 16 times smaller, and instead of trying to do all '0 to 15' at once, I would just do that 15 additional times. However, I think this may lead to inefficiency in synthesis and I don't feel like this is the right solution. EDIT: Tried what Ben said, instantiate_h_m_qa_pipeline_registers: for i in 1 to 16 generate instantiate_h_pipelined_reg : regn generic map ( N=> b, init => bzeros ) port map ( clk => clk , rst => '0', en => '1', input => h_blk_pipelined_input(i - 1), output=> h_blk_pipelined_input(i)); end generate instantiate_h_m_qa_pipeline_registers; The signals are now defined as: type std_logic_block is array (0 to 15) of std_logic_vector(iw - 1 downto 0) ; type partial_pipeline_registers_type is array (0 to 16) of std_logic_block; signal h_blk_pipelined_input : partial_pipeline_registers_type; And the error I get from XST is: ERROR:HDLParsers:800 - ((where the register part is)) Type of input is incompatible with type of h_blk_pipelined_input. I'm able to do everything I was able to do before, using ()() syntax instead of ( , ) so I haven't lost anything going this way, but it still doesn't resolve my problem.

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• Looking for a function that will split profits/loss equally between 2 business partners.

  - by Hamish Grubijan

  This is not homework, for I am not a student. This is for my general curiosity. I apologize if I am reinventing the wheel here.The function I seek can be defined as follows (language agnostic): int getPercentageOfA(double moneyA, double workA, double moneyB, double workB) { // Perhaps you may assume that workA == 0 // Compute result return result; } Suppose Alice and Bob want to do business together ... such as ... selling used books. Alice is only interested in investing money in it and nothing else. Bob might invest some money, but he might have no $ available to invest. He will, however, put in the effort in finding a seller, a buyer, and doing maintenance. There are no tools, education, health insurance costs, or other expenses to consider. Both Alice and Bob wish to split the profits "equally" (A different weight like 40/60 for advanced users). Both are entrepreneurs, so they deal with low ROI/wage, and high income alike. There is no fixed wage, minimum wage, fixed ROI, or minimum ROI. They try to find the best deal possible, assume risks and go for it. Now, let's stick with the 50/50 model. If Alice invests $100, Bob invests work, and they will end up with a profit (or loss) of $60, they will split it equally - either both get $30 for their efforts/investments, or Bob ends up owing $30 to Alice. A second possibility: Both Alice and Bob invest 100, then Bob does all the work, and they end up splitting $60 profit. It looks like Alice should get only $15, because $30 of that profit came from Bob's investment and Bob's effort, so Alice shall have none of it, and the other $30 is to be split 50/50. Both of the examples above are trivial even when A and B want to split it 35/65 or what have you. Now it gets more complicated: What if Alice invests $70, and Bob invests $30 + does all of the work. It appears simple: (70,30) = (30,30) + (40,0) ... but, if only we knew how to weigh the two parts relative to each other. Another complicated (I think) example: what if Alice and Bob invest $70 and $30 respectively, and also put in an equal amount of work? I have a few data points: When A and B put in the same amount of work and the same $ - 50/50. When A puts in 100% of the money, and B does 100% of the work - 50/50. When A does all of the work and puts in all of the money - 100 for A / 0 for B (and vice-versa). When A puts in 50% of the money, and B puts in 50% of the money as well as does all of the work - 25 for A, and 75 for B (and vice-versa). If I fix things such that always workA = 0%, workB = 100% of the total work, then getPercentageOfA becomes a function: height z given x and y. The question is - how do you extrapolate this function between these several points? What is this function? If you can cover the cases when workA does not have to be 0% of the total work, and when investment vs work is split as 85/15 or using some other model, then what would the new function be?

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• How to design a C / C++ library to be usable in many client languages?

  - by Brian Schimmel

  I'm planning to code a library that should be usable by a large number of people in on a wide spectrum of platforms. What do I have to consider to design it right? To make this questions more specific, there are four "subquestions" at the end. Choice of language Considering all the known requirements and details, I concluded that a library written in C or C++ was the way to go. I think the primary usage of my library will be in programs written in C, C++ and Java SE, but I can also think of reasons to use it from Java ME, PHP, .NET, Objective C, Python, Ruby, bash scrips, etc... Maybe I cannot target all of them, but if it's possible, I'll do it. Requirements It would be to much to describe the full purpose of my library here, but there are some aspects that might be important to this question: The library itself will start out small, but definitely will grow to enormous complexity, so it is not an option to maintain several versions in parallel. Most of the complexity will be hidden inside the library, though The library will construct an object graph that is used heavily inside. Some clients of the library will only be interested in specific attributes of specific objects, while other clients must traverse the object graph in some way Clients may change the objects, and the library must be notified thereof The library may change the objects, and the client must be notified thereof, if it already has a handle to that object The library must be multi-threaded, because it will maintain network connections to several other hosts While some requests to the library may be handled synchronously, many of them will take too long and must be processed in the background, and notify the client on success (or failure) Of course, answers are welcome no matter if they address my specific requirements, or if they answer the question in a general way that matters to a wider audience! My assumptions, so far So here are some of my assumptions and conclusions, which I gathered in the past months: Internally I can use whatever I want, e.g. C++ with operator overloading, multiple inheritance, template meta programming... as long as there is a portable compiler which handles it (think of gcc / g++) But my interface has to be a clean C interface that does not involve name mangling Also, I think my interface should only consist of functions, with basic/primitive data types (and maybe pointers) passed as parameters and return values If I use pointers, I think I should only use them to pass them back to the library, not to operate directly on the referenced memory For usage in a C++ application, I might also offer an object oriented interface (Which is also prone to name mangling, so the App must either use the same compiler, or include the library in source form) Is this also true for usage in C# ? For usage in Java SE / Java EE, the Java native interface (JNI) applies. I have some basic knowledge about it, but I should definitely double check it. Not all client languages handle multithreading well, so there should be a single thread talking to the client For usage on Java ME, there is no such thing as JNI, but I might go with Nested VM For usage in Bash scripts, there must be an executable with a command line interface For the other client languages, I have no idea For most client languages, it would be nice to have kind of an adapter interface written in that language. I think there are tools to automatically generate this for Java and some others For object oriented languages, it might be possible to create an object oriented adapter which hides the fact that the interface to the library is function based - but I don't know if its worth the effort Possible subquestions is this possible with manageable effort, or is it just too much portability? are there any good books / websites about this kind of design criteria? are any of my assumptions wrong? which open source libraries are worth studying to learn from their design / interface / souce? meta: This question is rather long, do you see any way to split it into several smaller ones? (If you reply to this, do it as a comment, not as an answer)

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• Ajax and using responseXML

  - by Banderdash

  Hello, I have a XML file that looks like this: <response> <library name="My Library"> <book id="1" checked-out="1"> <authors> <author>David Flanagan</author> </authors> <title>JavaScript: The Definitive Guide</title> <isbn-10>0596101996</isbn-10> </book> <book id="2" checked-out="1"> <authors> <author>John Resig</author> </authors> <title>Pro JavaScript Techniques (Pro)</title> <isbn-10>1590597273</isbn-10> </book> <book id="3" checked-out="0"> <authors> <author>Erich Gamma</author> <author>Richard Helm</author> <author>Ralph Johnson</author> <author>John M. Vlissides</author> </authors> <title>Design Patterns: Elements of Reusable Object-Oriented Software</title> <isbn-10>0201633612</isbn-10> </book> ... </library> </response> I'm using a simple JS script to, on click show all the titles of the books: <script type="text/javascript"> function loadXMLDoc() { if (window.XMLHttpRequest) {// code for IE7+, Firefox, Chrome, Opera, Safari xmlhttp=new XMLHttpRequest(); } else {// code for IE6, IE5 xmlhttp=new ActiveXObject("Microsoft.XMLHTTP"); } xmlhttp.onreadystatechange=function() { if (xmlhttp.readyState==4 && xmlhttp.status==200) { xmlDoc=xmlhttp.responseXML; var txt=""; x=xmlDoc.getElementsByTagName("title"); for (i=0;i<x.length;i++) { txt=txt + x[i].childNodes[0].nodeValue + "<br />"; } document.getElementById("checkedIn").innerHTML=txt; } } xmlhttp.open("GET","ajax-response-data.xml",true); xmlhttp.send(); } </script> This works fine, as you can see here: http://clients.pixelbleed.net/ajax-test/ What I'd like to do is have the results post, on page load (not on click) into two separate DIV's depending on checked-out variable in the XML. So <book id="#" checked-out="1"> would post to the checkedIn div, <book id="#" checked-out="0"> posts to a checkedOut div. Also want to display the title and the author--would love any ideas as best method for accomplishing this. Apologize in advanced for the newbieness of my query.

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• Modern alternatives to Java

  - by Ralph

  I have been a Java developer for 14 years and have written an enterprise-level (~500 kloc) Swing application that uses most of the standard library APIs. Recently, I have become disappointed with the progress that the language has made to "modernize" itself, and am looking for an alternative for ongoing development. I have considered moving to the .NET platform, but I have issues with using something the only runs well in Windows (I know about Mono, but that is still far behind Microsoft). I also plan on buying a new Macbook Pro as soon as Apple releases their new rumored Arrandale-based machines and want to develop in an environment that will feel "at home" in Unix/Linux. I have considered using Python or Ruby, but the standard Java library is arguably the largest of any modern language. In JVM-based languages, I looked at Groovy, but am disappointed with its performance. Rumor has it that with the soon-to-be released JDK7, with its InvokeDynamic instruction, this will improve, but I don't know how much. Groovy is also not truly a functional language, although it provides closures and some of the "functional" features on collections. It does not embrace immutability. I have narrowed my search down to two JVM-based alternatives: Scala and Clojure. Each has its strengths and weaknesses. I am looking for opinions. I am not an expert at either of these languages; I have read 2 1/2 books on Scala and am currently reading Stu Halloway's book on Clojure. Scala is strongly statically typed. I know the dynamic language folks claim that static typing is a crutch for not doing unit testing, but it does provide a mechanism for compile-time location of a whole class of errors. Scala is more concise than Java, but not as much as Clojure. Scala's inter-operation with Java seems to be better than Clojure's, in that most Java operations are easier to do in Scala than in Clojure. For example, I can find no way in Clojure to create a non-static initialization block in a class derived from a Java superclass. For example, I like the Apache commons CLI library for command line argument parsing. In Java and Scala, I can create a new Options object and add Option items to it in an initialization block as follows (Java code): final Options options = new Options() { { addOption(new Option("?", "help", false, "Show this usage information"); // other options } }; I can't figure out how to the same thing in Clojure (except by using (doit...)), although that may reflect my lack of knowledge of the language. Clojure's collections are optimized for immutability. They rarely require copy-on-write semantics. I don't know if Scala's immutable collections are implemented using similar algorithms, but Rich Hickey (Clojure's inventor) goes out of his way to explain how that language's data structures are efficient. Clojure was designed from the beginning for concurrency (as was Scala) and with modern multi-core processors, concurrency takes on more importance, but I occasionally need to write simple non-concurrent utilities, and Scala code probably runs a little faster for these applications since it discourages, but does not prohibit, "simple" mutability. One could argue that one-off utilities do not have to be super-fast, but sometimes they do tasks that take hours or days to complete. I know that there is no right answer to this "question", but I thought I would open it up for discussion. Are there other JVM-based languages that can be used for enterprise level development?

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• "C variable type sizes are machine dependent." Is it really true? signed & unsigned numbers ;

  - by claws

  Hello, I've been told that C types are machine dependent. Today I wanted to verify it. void legacyTypes() { /* character types */ char k_char = 'a'; //Signedness --> signed & unsigned signed char k_char_s = 'a'; unsigned char k_char_u = 'a'; /* integer types */ int k_int = 1; /* Same as "signed int" */ //Signedness --> signed & unsigned signed int k_int_s = -2; unsigned int k_int_u = 3; //Size --> short, _____, long, long long short int k_s_int = 4; long int k_l_int = 5; long long int k_ll_int = 6; /* real number types */ float k_float = 7; double k_double = 8; } I compiled it on a 32-Bit machine using minGW C compiler _legacyTypes: pushl %ebp movl %esp, %ebp subl $48, %esp movb $97, -1(%ebp) # char movb $97, -2(%ebp) # signed char movb $97, -3(%ebp) # unsigned char movl $1, -8(%ebp) # int movl $-2, -12(%ebp)# signed int movl $3, -16(%ebp) # unsigned int movw $4, -18(%ebp) # short int movl $5, -24(%ebp) # long int movl $6, -32(%ebp) # long long int movl $0, -28(%ebp) movl $0x40e00000, %eax movl %eax, -36(%ebp) fldl LC2 fstpl -48(%ebp) leave ret I compiled the same code on 64-Bit processor (Intel Core 2 Duo) on GCC (linux) legacyTypes: .LFB2: .cfi_startproc pushq %rbp .cfi_def_cfa_offset 16 movq %rsp, %rbp .cfi_offset 6, -16 .cfi_def_cfa_register 6 movb $97, -1(%rbp) # char movb $97, -2(%rbp) # signed char movb $97, -3(%rbp) # unsigned char movl $1, -12(%rbp) # int movl $-2, -16(%rbp)# signed int movl $3, -20(%rbp) # unsigned int movw $4, -6(%rbp) # short int movq $5, -32(%rbp) # long int movq $6, -40(%rbp) # long long int movl $0x40e00000, %eax movl %eax, -24(%rbp) movabsq $4620693217682128896, %rax movq %rax, -48(%rbp) leave ret Observations char, signed char, unsigned char, int, unsigned int, signed int, short int, unsigned short int, signed short int all occupy same no. of bytes on both 32-Bit & 64-Bit Processor. The only change is in long int & long long int both of these occupy 32-bit on 32-bit machine & 64-bit on 64-bit machine. And also the pointers, which take 32-bit on 32-bit CPU & 64-bit on 64-bit CPU. Questions: I cannot say, what the books say is wrong. But I'm missing something here. What exactly does "Variable types are machine dependent mean?" As you can see, There is no difference between instructions for unsigned & signed numbers. Then how come the range of numbers that can be addressed using both is different? I was reading http://stackoverflow.com/questions/2511246/how-to-maintain-fixed-size-of-c-variable-types-over-different-machines I didn't get the purpose of the question or their answers. What maintaining fixed size? They all are the same. I didn't understand how those answers are going to ensure the same size.

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