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• Synergy 1.5 crash (OSX 10.6.8)

  - by Oliver

  THANKS FOR TAKING THE TIME TO READ THIS I recently installed Synergy 1.5 r2278 (for Mac OSX 10.6.8) and was using it fine for most of the day, then it decided to stop working (the only thing I changed systemwise was the screensaver - and then after it started crashing disabled it - to see if it would resolve). When I start Synergy (on the Mac - Client) it says: after about 5 seconds (and successfully connecting to the Server) "synergyc quit unexpectedly" Here is the crash log (w/ binery info removed - too long for post requirements) Process: synergyc [1026] Path: /Applications/Synergy.app/Contents/MacOS/synergyc Identifier: synergy Version: ??? (???) Code Type: X86 (Native) Parent Process: Synergy [1023] Date/Time: 2014-05-28 15:36:17.746 +0930 OS Version: Mac OS X 10.6.8 (10K549) Report Version: 6 Interval Since Last Report: 2144189 sec Crashes Since Last Report: 23 Per-App Interval Since Last Report: 10242 sec Per-App Crashes Since Last Report: 9 Anonymous UUID: 86D5A57C-13D4-470E-AC72-48ACDDDE5EB0 Exception Type: EXC_CRASH (SIGABRT) Exception Codes: 0x0000000000000000, 0x0000000000000000 Crashed Thread: 5 Application Specific Information: abort() called Thread 0: Dispatch queue: com.apple.main-thread 0 libSystem.B.dylib 0x95cf3afa mach_msg_trap + 10 1 libSystem.B.dylib 0x95cf4267 mach_msg + 68 2 com.apple.CoreFoundation 0x95af02df __CFRunLoopRun + 2079 3 com.apple.CoreFoundation 0x95aef3c4 CFRunLoopRunSpecific + 452 4 com.apple.CoreFoundation 0x95aef1f1 CFRunLoopRunInMode + 97 5 com.apple.HIToolbox 0x93654e04 RunCurrentEventLoopInMode + 392 6 com.apple.HIToolbox 0x93654bb9 ReceiveNextEventCommon + 354 7 com.apple.HIToolbox 0x937dd137 ReceiveNextEvent + 83 8 synergyc 0x000356d0 COSXEventQueueBuffer::waitForEvent(double) + 48 9 synergyc 0x00010dd5 CEventQueue::getEvent(CEvent&, double) + 325 10 synergyc 0x00011fb0 CEventQueue::loop() + 272 11 synergyc 0x00044eb6 CClientApp::mainLoop() + 134 12 synergyc 0x0005c509 standardStartupStatic(int, char**) + 41 13 synergyc 0x000448a9 CClientApp::runInner(int, char**, ILogOutputter*, int (*)(int, char**)) + 137 14 synergyc 0x0005c4b0 CAppUtilUnix::run(int, char**) + 64 15 synergyc 0x000427df CApp::run(int, char**) + 63 16 synergyc 0x00006e65 main + 117 17 synergyc 0x00006dd9 start + 53 Thread 1: 0 libSystem.B.dylib 0x95d607da __sigwait + 10 1 libSystem.B.dylib 0x95d607b6 sigwait$UNIX2003 + 71 2 synergyc 0x00009583 CArchMultithreadPosix::threadSignalHandler(void*) + 67 3 libSystem.B.dylib 0x95d21259 _pthread_start + 345 4 libSystem.B.dylib 0x95d210de thread_start + 34 Thread 2: 0 libSystem.B.dylib 0x95d21aa2 __semwait_signal + 10 1 libSystem.B.dylib 0x95d2175e _pthread_cond_wait + 1191 2 libSystem.B.dylib 0x95d212b1 pthread_cond_timedwait$UNIX2003 + 72 3 synergyc 0x00009476 CArchMultithreadPosix::waitCondVar(CArchCondImpl*, CArchMutexImpl*, double) + 150 4 synergyc 0x0002b18f CCondVarBase::wait(double) const + 63 5 synergyc 0x0002ce68 CSocketMultiplexer::serviceThread(void*) + 136 6 synergyc 0x0002d698 TMethodJob<CSocketMultiplexer>::run() + 40 7 synergyc 0x0002b8f4 CThread::threadFunc(void*) + 132 8 synergyc 0x00008f30 CArchMultithreadPosix::doThreadFunc(CArchThreadImpl*) + 80 9 synergyc 0x0000902a CArchMultithreadPosix::threadFunc(void*) + 74 10 libSystem.B.dylib 0x95d21259 _pthread_start + 345 11 libSystem.B.dylib 0x95d210de thread_start + 34 Thread 3: Dispatch queue: com.apple.libdispatch-manager 0 libSystem.B.dylib 0x95d1a382 kevent + 10 1 libSystem.B.dylib 0x95d1aa9c _dispatch_mgr_invoke + 215 2 libSystem.B.dylib 0x95d19f59 _dispatch_queue_invoke + 163 3 libSystem.B.dylib 0x95d19cfe _dispatch_worker_thread2 + 240 4 libSystem.B.dylib 0x95d19781 _pthread_wqthread + 390 5 libSystem.B.dylib 0x95d195c6 start_wqthread + 30 Thread 4: 0 libSystem.B.dylib 0x95d19412 __workq_kernreturn + 10 1 libSystem.B.dylib 0x95d199a8 _pthread_wqthread + 941 2 libSystem.B.dylib 0x95d195c6 start_wqthread + 30 Thread 5 Crashed: 0 libSystem.B.dylib 0x95d610ee __semwait_signal_nocancel + 10 1 libSystem.B.dylib 0x95d60fd2 nanosleep$NOCANCEL$UNIX2003 + 166 2 libSystem.B.dylib 0x95ddbfb2 usleep$NOCANCEL$UNIX2003 + 61 3 libSystem.B.dylib 0x95dfd6f0 abort + 105 4 libSystem.B.dylib 0x95d79b1b _Unwind_Resume + 59 5 synergyc 0x00008fd1 CArchMultithreadPosix::doThreadFunc(CArchThreadImpl*) + 241 6 synergyc 0x0000902a CArchMultithreadPosix::threadFunc(void*) + 74 7 libSystem.B.dylib 0x95d21259 _pthread_start + 345 8 libSystem.B.dylib 0x95d210de thread_start + 34 Thread 5 crashed with X86 Thread State (32-bit): eax: 0x0000003c ebx: 0x95d60f39 ecx: 0xb0288a7c edx: 0x95d610ee edi: 0x00521950 esi: 0xb0288ad8 ebp: 0xb0288ab8 esp: 0xb0288a7c ss: 0x0000001f efl: 0x00000247 eip: 0x95d610ee cs: 0x00000007 ds: 0x0000001f es: 0x0000001f fs: 0x0000001f gs: 0x00000037 cr2: 0x002fe000 Model: MacBook2,1, BootROM MB21.00A5.B07, 2 processors, Intel Core 2 Duo, 2.16 GHz, 2 GB

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• Why Photoshop CS5's photomerge's result immediately disappear?

  - by koiyu

  I have a bunch of JPG-files which I want to stitch together with Photoshop's Photomerge function. I choose File → Automate → Photomerge... and browse for the files. Photoshop opens the files and starts analyzing. I see the process bar filling and different phases are mentioned on the process bar. Nothing weird there. When the merging is done (and if I don't blink my eyes), I can see layers-palette is populated with the chosen files and, by quickly judging from the layer thumbnails, they're properly aligned. Sometimes the image window itself can be seen, but not always. Problem is that the layers and the image disappear in a flash. There is no error message. Everything is like prior starting the photomerge. No file has been changed. I could continue to use Photoshop normally. This is what I've tried so far: Loaded folder which has 38 JPG images, 4272 x 2848 and ˜ 5 megabytes per file Loaded the same files, but chose Use Files instead of Use Folder in the photomerge's window Loaded 19 JPG images, 4272 x 2848 and ˜ 5 megabytes per file Loaded 10 JPG images, ⇑ see above Loaded 5 JPG images, see above Loaded 3 JPG images, see above Scaled the images to 2256 x 1504 and ˜< 1 megabytes per file Loaded in a set of 38, 19, 10, 5, 3 Following steps are tested with these smaller files and with a set of 5 images Read Adobe's forums and reduced the amount of RAM Photoshop uses gradually from ˜ 80 % to 50 % (though I didn't understand the logic behind this) Would've reduced cache tile size to 128K, but it was set so already Disabled OpenGL Scaled the images to 800 x 533 and ˜ 100 kilobytes per file, loaded a set of 5 Read more unanswered threads around the internet In between each test I closed and reopened Photoshop. This is the first time I've even tried using photomerge. Am I doing something wrong? How can I locate what is the problem? How do I fix this? Photoshop is 64 bit Extended CS5 version. I'm on a mid-2010 quad-core (i5) iMac with up-to-date Mac OS X 10.6.6. Edit: Weird. First loading the images into one file via File → Scripts → Load Files into Stack… and then using Edit → Auto-Align Layers…, which, effectively, is the same as photomerge (even the dialog looks kind of the same), works! Even with the original JPGs without any issues. This doesn't fix photomerge, though.

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• How to loop through all illustrator files in a folder (CS6)

  - by Julian

  I have written some JavaScript to save .ai files to two separate locations with different resolutions, one of them being cropped to a reduced size art board. (Courtesy of John Otterud / Articmill for the main part). There are other variables in the script that I am not using at present but I want to leave the functionality there for a later date/additional layers to export/other resolutions etc. I can't get it to loop through all files in a folder. I cannot find the script that works - or insert it at the right place. I can get as far a selecting the folder and I suppose creating an array but after that what next? This is the create array part of the script - // JavaScript Document //Set up vairaibles var destDoc, sourceDoc, sourceFolder, newLayer; // Select the source folder. sourceFolder = Folder.selectDialog('Select the folder with Illustrator files that you want to mere into one', '~'); destDoc = app.documents.add(); // If a valid folder is selected if (sourceFolder != null) { files = new Array(); // Get all files matching the pattern files = sourceFolder.getFiles(); I have inserted this at the beginning of the main script (probably where I am going wrong because I can select the folder but then nothing more) #target illustrator var docRef = app.activeDocument; with (docRef) { if (layers[i].name = 'HEADER') { layers[i].name = '#'+ activeDocument.name; save() } } // *** Export Layers as PNG files (in multiple resolutions) *** var subFolderName = "For_PLMA"; var subFolderTwoName = "For_VLP"; var saveInMultipleResolutions = true; // ... // Note: only use one character! var exportLayersStartingWith = "%"; var exportLayersWithArtboardClippingStartingWith = "#"; // ... var normalResolutionFileAppend = "_VLP"; var highResolutionFileAppend = "_PLMA"; // ... var normalResolutionScale = 100; var highResolutionScale = 200; var veryhighResolutionScale = 300; // *** Start of script *** var doc = app.activeDocument; // Make sure we have saved the document if (doc.path != "") { Then the rest of the export script runs on from there.

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• How to decrypt a string in C# that was encrypted in Delphi

  - by Simon Linder

  Hi all, we have a project written in Delphi that we want to convert to C#. Problem is that we have some passwords and settings that are encrypted and written into the registry. When we need a specified password we get it from the registry and decrypt it so we can use it. For the conversion into C# we have to do it the same way so that the application can also be used by users that have the old version and want to upgrade it. Here is the code we use to encrypt/decrypt strings in Delphi: unit uCrypt; interface function EncryptString(strPlaintext, strPassword : String) : String; function DecryptString(strEncryptedText, strPassword : String) : String; implementation uses DCPcrypt2, DCPblockciphers, DCPdes, DCPmd5; const CRYPT_KEY = '1q2w3e4r5t6z7u8'; function EncryptString(strPlaintext) : String; var cipher : TDCP_3des; strEncryptedText : String; begin if strPlaintext <> '' then begin try cipher := TDCP_3des.Create(nil); try cipher.InitStr(CRYPT_KEY, TDCP_md5); strEncryptedText := cipher.EncryptString(strPlaintext); finally cipher.Free; end; except strEncryptedText := ''; end; end; Result := strEncryptedText; end; function DecryptString(strEncryptedText) : String; var cipher : TDCP_3des; strDecryptedText : String; begin if strEncryptedText <> '' then begin try cipher := TDCP_3des.Create(nil); try cipher.InitStr(CRYPT_KEY, TDCP_md5); strDecryptedText := cipher.DecryptString(strEncryptedText); finally cipher.Free; end; except strDecryptedText := ''; end; end; Result := strDecryptedText; end; end. So for example when we want to encrypt the string asdf1234 we get the result WcOb/iKo4g8=. We now want to decrypt that string in C#. Here is what we tried to do: public static void Main(string[] args) { string Encrypted = "WcOb/iKo4g8="; string Password = "1q2w3e4r5t6z7u8"; string DecryptedString = DecryptString(Encrypted, Password); } public static string DecryptString(string Message, string Passphrase) { byte[] Results; System.Text.UTF8Encoding UTF8 = new System.Text.UTF8Encoding(); // Step 1. We hash the passphrase using MD5 // We use the MD5 hash generator as the result is a 128 bit byte array // which is a valid length for the TripleDES encoder we use below MD5CryptoServiceProvider HashProvider = new MD5CryptoServiceProvider(); byte[] TDESKey = HashProvider.ComputeHash(UTF8.GetBytes(Passphrase)); // Step 2. Create a new TripleDESCryptoServiceProvider object TripleDESCryptoServiceProvider TDESAlgorithm = new TripleDESCryptoServiceProvider(); // Step 3. Setup the decoder TDESAlgorithm.Key = TDESKey; TDESAlgorithm.Mode = CipherMode.ECB; TDESAlgorithm.Padding = PaddingMode.None; // Step 4. Convert the input string to a byte[] byte[] DataToDecrypt = Convert.FromBase64String(Message); // Step 5. Attempt to decrypt the string try { ICryptoTransform Decryptor = TDESAlgorithm.CreateDecryptor(); Results = Decryptor.TransformFinalBlock(DataToDecrypt, 0, DataToDecrypt.Length); } finally { // Clear the TripleDes and Hashprovider services of any sensitive information TDESAlgorithm.Clear(); HashProvider.Clear(); } // Step 6. Return the decrypted string in UTF8 format return UTF8.GetString(Results); } Well the result differs from the expected result. After we call DecryptString() we expect to get asdf1234but we get something else. Does anyone have an idea of how to decrypt that correctly? Thanks in advance Simon

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• .NET: Serializing object to a file from a 3rd party assembly

  - by MacGyver

  Below is a link that describes how to serialize an object. But it requires you implement from ISerializable for the object you are serializing. What I'd like to do is serialize an object that I did not define--an object based on a class in a 3rd party assembly (from a project reference) that is not implementing ISerializable. Is that possible? How can this be done? http://www.switchonthecode.com/tutorials/csharp-tutorial-serialize-objects-to-a-file Property (IWebDriver = interface type): private IWebDriver driver; Object Instance (FireFoxDriver is a class type): driver = new FirefoxDriver(firefoxProfile); ================ 3/21/2012 update after answer posted Why would this throw an error? It doesn't like this line: serializedObject.DriverInstance = (FirefoxDriver)driver; ... Error: Cannot implicitly convert type 'OpenQA.Selenium.IWebDriver' to 'OpenQA.Selenium.Firefox.FirefoxDriver'. An explicit conversion exists (are you missing a cast?) Here is the code: FirefoxDriverSerialized serializedObject = new FirefoxDriverSerialized(); Serializer serializer = new Serializer(); serializedObject = serializer.DeSerializeObject(@"C:\firefoxDriver.qa"); driver = serializedObject.DriverInstance; if (driver == null) { driver = new FirefoxDriver(firefoxProfile); serializedObject.DriverInstance = (FirefoxDriverSerialized)driver; serializer.SerializeObject(@"C:\firefoxDriver.qa", serializedObject); } Here are the two Serializer classes I built: public class Serializer { public Serializer() { } public void SerializeObject(string filename, FirefoxDriverSerialized objectToSerialize) { Stream stream = File.Open(filename, FileMode.Create); BinaryFormatter bFormatter = new BinaryFormatter(); bFormatter.Serialize(stream, objectToSerialize); stream.Close(); } public FirefoxDriverSerialized DeSerializeObject(string filename) { FirefoxDriverSerialized objectToSerialize; Stream stream = File.Open(filename, FileMode.Open); BinaryFormatter bFormatter = new BinaryFormatter(); objectToSerialize = (FirefoxDriverSerialized)bFormatter.Deserialize(stream); stream.Close(); return objectToSerialize; } } [Serializable()] public class FirefoxDriverSerialized : FirefoxDriver, ISerializable { private FirefoxDriver driverInstance; public FirefoxDriver DriverInstance { get { return this.driverInstance; } set { this.driverInstance = value; } } public FirefoxDriverSerialized() { } public FirefoxDriverSerialized(SerializationInfo info, StreamingContext ctxt) { this.driverInstance = (FirefoxDriver)info.GetValue("DriverInstance", typeof(FirefoxDriver)); } public void GetObjectData(SerializationInfo info, StreamingContext ctxt) { info.AddValue("DriverInstance", this.driverInstance); } } ================= 3/23/2012 update #2 - fixed serialization/de-serialization, but having another issue (might be relevant for new question) This fixed the calling code. Because we're deleting the *.qa file when we call the WebDriver.Quit() because that's when we chose to close the browser. This will kill off our cached driver as well. So if we start with a new browser window, we'll hit the catch block and create a new instance and save it to our *.qa file (in the serialized form). FirefoxDriverSerialized serializedObject = new FirefoxDriverSerialized(); Serializer serializer = new Serializer(); try { serializedObject = serializer.DeSerializeObject(@"C:\firefoxDriver.qa"); driver = serializedObject.DriverInstance; } catch { driver = new FirefoxDriver(firefoxProfile); serializedObject = new FirefoxDriverSerialized(); serializedObject.DriverInstance = (FirefoxDriver)driver; serializer.SerializeObject(@"C:\firefoxDriver.qa", serializedObject); } However, still getting this exception: Acu.QA.Main.Test_0055_GiftCertificate_UserCheckout: SetUp : System.Runtime.Serialization.SerializationException : Type 'OpenQA.Selenium.Firefox.FirefoxDriver' in Assembly 'WebDriver, Version=2.16.0.0, Culture=neutral, PublicKeyToken=1c2bd1631853048f' is not marked as serializable. TearDown : System.NullReferenceException : Object reference not set to an instance of an object. The 3rd line in this code block is throwing the exception: public void SerializeObject(string filename, FirefoxDriverSerialized objectToSerialize) { Stream stream = File.Open(filename, FileMode.Create); BinaryFormatter bFormatter = new BinaryFormatter(); bFormatter.Serialize(stream, objectToSerialize); // <=== this line stream.Close(); }

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• Convert NSData to primitive variable with ieee-754 or twos-complement ?

  - by William GILLARD

  Hi every one. I am new programmer in Obj-C and cocoa. Im a trying to write a framework which will be used to read a binary files (Flexible Image Transport System or FITS binary files, usually used by astronomers). The binary data, that I am interested to extract, can have various formats and I get its properties by reading the header of the FITS file. Up to now, I manage to create a class to store the content of the FITS file and to isolate the header into a NSString object and the binary data into a NSData object. I also manage to write method which allow me to extract the key values from the header that are very valuable to interpret the binary data. I am now trying to convert the NSData object into a primitive array (array of double, int, short ...). But, here, I get stuck and would appreciate any help. According to the documentation I have about the FITS file, I have 5 possibilities to interpret the binary data depending on the value of the BITPIX key: BITPIX value | Data represented 8 | Char or unsigned binary int 16 | 16-bit two's complement binary integer 32 | 32-bit two's complement binary integer 64 | 64-bit two's complement binary integer -32 | IEEE single precision floating-point -64 | IEEE double precision floating-point I already write the peace of code, shown bellow, to try to convert the NSData into a primitive array. // self reefer to my FITS class which contain a NSString object // with the content of the header and a NSData object with the binary data. -(void*) GetArray { switch (BITPIX) { case 8: return [self GetArrayOfUInt]; break; case 16: return [self GetArrayOfInt]; break; case 32: return [self GetArrayOfLongInt]; break; case 64: return [self GetArrayOfLongLong]; break; case -32: return [self GetArrayOfFloat]; break; case -64: return [self GetArrayOfDouble]; break; default: return NULL; } } // then I show you the method to convert the NSData into a primitive array. // I restrict my example to the case of 'double'. Code is similar for other methods // just change double by 'unsigned int' (BITPIX 8), 'short' (BITPIX 16) // 'int' (BITPIX 32) 'long lon' (BITPIX 64), 'float' (BITPIX -32). -(double*) GetArrayOfDouble { int Nelements=[self NPIXEL]; // Metod to extract, from the header // the number of element into the array NSLog(@"TOTAL NUMBER OF ELEMENTS [%i]\n",Nelements); //CREATE THE ARRAY double (*array)[Nelements]; // Get the total number of bits in the binary data int Nbit = abs(BITPIX)*GCOUNT*(PCOUNT + Nelements); // GCOUNT and PCOUNT are defined // into the header NSLog(@"TOTAL NUMBER OF BIT [%i]\n",Nbit); int i=0; //FILL THE ARRAY double Value; for(int bit=0; bit < Nbit; bit+=sizeof(double)) { [Img getBytes:&Value range:NSMakeRange(bit,sizeof(double))]; NSLog(@"[%i]:(%u)%.8G\n",i,bit,Value); (*array)[i]=Value; i++; } return (*array); } However, the value I print in the loop are very different from the expected values (compared using official FITS software). Therefore, I think that the Obj-C double does not use the IEEE-754 convention as well as the Obj-C int are not twos-complement. I am really not familiar with this two convention (IEEE and twos-complement) and would like to know how I can do this conversion with Obj-C. In advance many thanks for any help or information.

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• Convert extended ASCII characters to it's right presentation using Console.ReadKey() method and ConsoleKeyInfo variable

  - by mishamosher

  Readed about 30 minutes, and didn't found some specific for this in this site. Suppose the following, in C#, console application: ConsoleKeyInfo cki; cki = Console.ReadKey(true); Console.WriteLine(cki.KeyChar.ToString()); //Or Console.WriteLine(cki.KeyChar) as well Console.ReadKey(true); Now, let's put ¿ in the console entry, and asign it to cki via a Console.ReadKey(true). What will be shown isn't the ¿ symbol, the ¨ symbol is the one that's shown instead. And the same happens with many other characters. Examples: ñ shows ¤, ¡ shows -, ´ shows ï. Now, let's take the same code snipplet and add some things for a more Console.ReadLine() like behavior: string data = string.Empty; ConsoleKeyInfo cki; for (int i = 0; i < 10; i++) { cki = Console.ReadKey(true); data += cki.KeyChar; } Console.WriteLine(data); Console.ReadKey(true); The question, how to handle this by the right way, end printing the right characters that should be stored on data, not things like ¨, ¤, -, ï, etc? Please note that I want a solution that works with ConsoleKeyInfo and Console.ReadKey(), not use other variable types, or read methods. EDIT: Because ReadKey() method, that comes from Console namespace, depends on Kernel32.dll and it definetively bad handles the extended ASCII and unicode, it's not an option anymore to just find a valid conversion for what it returns. The only valid way to handle the bad behavior of ReadKey() is to use the cki.Key property that's written in cki = Console.ReadKey(true) execution and apply a switch to it, then, return the right values on dependence of what key was pressed. For example, to handle the Ñ key pressing: string data = string.Empty; ConsoleKeyInfo cki; cki = Console.ReadKey(true); switch (cki.Key) { case ConsoleKey.Oem3: if (cki.Modifiers.ToString().Contains("Shift")) //Could added handlers for Alt and Control, but not putted in here to keep the code small and simple data += "Ñ"; else data += "ñ"; break; } Console.WriteLine(data); Console.ReadKey(true); So, now the question has a wider focus... Which others functions completes it's execution with only one key pressed, and returns what's pressed (a substitute of ReadKey())? I think that there's not such substitutes, but a confirmed answer would be usefull. EDIT2: HA! Found the way, for something I used for so many times Windows 98 SE. There are the codepages, the ones responsibles for how's presented the info in the console. ReadLine() reconfigures the codepage to use properly the extended ASCII and Unicode characters. ReadKey() leaves it in EN-US default (codepage 850). Just use a codepage that prints the characters you want, and that's all. Refer to http://en.wikipedia.org/wiki/Code_page for some of them :) So, for the Ñ key press, the solution is this: Console.OutputEncoding = Encoding.GetEncoding(1252); //Also 28591 is valid for `Ñ` key, and others too string data = string.Empty; ConsoleKeyInfo cki; cki = Console.ReadKey(true); data += cki.KeyChar; Console.WriteLine(data); Console.ReadKey(true); Simple :) Now I'm wrrr with myself... how could I forget those codepages!? Question answered, so, no more about this!

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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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• STL operator= behavior change with Visual Studio 2010?

  - by augnob

  Hi, I am attempting to compile QtScriptGenerator (gitorious) with Visual Studio 2010 (C++) and have run into a compile error. In searching for a solution, I have seen occasional references to compile breakages introduced since VS2008 due to changes in VS2010's implementation of STL and/or c++0x conformance changes. Any ideas what is happening below, or how I could go about fixing it? If the offending code appeared to be QtScriptGenerator's, I think I would have an easier time fixing it.. but it appears to me that the offending code may be in VS2010's STL implementation and I may be required to create a workaround? PS. I am pretty unfamiliar with templates and STL. I have a background in embedded and console projects where such things have until recently often been avoided to reduce memory consumption and cross-compiler risks. C:\Program Files\Microsoft Visual Studio 10.0\VC\INCLUDE\xutility(275) : error C2679: binary '=' : no operator found which takes a right-hand operand of type 'rpp::pp_output_iterator<_Container>' (or there is no acceptable conversion) with [ _Container=std::string ] c:\qt\qtscriptgenerator\generator\parser\rpp\pp-iterator.h(75): could be 'rpp::pp_output_iterator<_Container> &rpp::pp_output_iterator<_Container>::operator =(const char &)' with [ _Container=std::string ] while trying to match the argument list '(rpp::pp_output_iterator<_Container>, rpp::pp_output_iterator<_Container>)' with [ _Container=std::string ] C:\Program Files\Microsoft Visual Studio 10.0\VC\INCLUDE\xutility(2176) : see reference to function template instantiation '_Iter &std::_Rechecked<_OutIt,_OutIt>(_Iter &,_UIter)' being compiled with [ _Iter=rpp::pp_output_iterator<std::string>, _OutIt=rpp::pp_output_iterator<std::string>, _UIter=rpp::pp_output_iterator<std::string> ] c:\qt\qtscriptgenerator\generator\parser\rpp\pp-internal.h(83) : see reference to function template instantiation '_OutIt std::copy<std::_String_iterator<_Elem,_Traits,_Alloc>,_OutputIterator>(_InIt,_InIt,_OutIt)' being compiled with [ _OutIt=rpp::pp_output_iterator<std::string>, _Elem=char, _Traits=std::char_traits<char>, _Alloc=std::allocator<char>, _OutputIterator=rpp::pp_output_iterator<std::string>, _InIt=std::_String_iterator<char,std::char_traits<char>,std::allocator<char>> ] c:\qt\qtscriptgenerator\generator\parser\rpp\pp-engine-bits.h(500) : see reference to function template instantiation 'void rpp::_PP_internal::output_line<_OutputIterator>(const std::string &,int,_OutputIterator)' being compiled with [ _OutputIterator=rpp::pp_output_iterator<std::string> ] C:\Program Files\Microsoft Visual Studio 10.0\VC\INCLUDE\xutility(275) : error C2582: 'operator =' function is unavailable in 'rpp::pp_output_iterator<_Container>' with [ _Container=std::string ] Here's some context.. pp-internal.h-- #ifndef PP_INTERNAL_H #define PP_INTERNAL_H #include <algorithm> #include <stdio.h> namespace rpp { namespace _PP_internal { .. 68 template <typename _OutputIterator> 69 void output_line(const std::string &__filename, int __line, _OutputIterator __result) 70 { 71 std::string __msg; 72 73 __msg += "# "; 74 75 char __line_descr[16]; 76 pp_snprintf (__line_descr, 16, "%d", __line); 77 __msg += __line_descr; 78 79 __msg += " \""; 80 81 if (__filename.empty ()) 82 __msg += "<internal>"; 83 else 84 __msg += __filename; 85 86 __msg += "\"\n"; 87 std::copy (__msg.begin (), __msg.end (), __result); 88 }

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• How to change by using CVGrayscaleMat

  - by Babul

  With the following code the image showed as above is converted as below image... Their it's showing black background with gray lines.....i want white background with gray lines .. Please guide me .. i am new to iPhone Thanks alot in Advance - (void)viewDidLoad { [super viewDidLoad]; // Initialise video capture - only supported on iOS device NOT simulator #if TARGET_IPHONE_SIMULATOR NSLog(@"Video capture is not supported in the simulator"); #else _videoCapture = new cv::VideoCapture; if (!_videoCapture->open(CV_CAP_AVFOUNDATION)) { NSLog(@"Failed to open video camera"); } #endif // Load a test image and demonstrate conversion between UIImage and cv::Mat UIImage *testImage = [UIImage imageNamed:@"testimage.jpg"]; double t; int times = 10; //-------------------------------- // Convert from UIImage to cv::Mat NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init]; t = (double)cv::getTickCount(); for (int i = 0; i < times; i++) { cv::Mat tempMat = [testImage CVMat]; } t = 1000 * ((double)cv::getTickCount() - t) / cv::getTickFrequency() / times; [pool release]; NSLog(@"UIImage to cv::Mat: %gms", t); //------------------------------------------ // Convert from UIImage to grayscale cv::Mat pool = [[NSAutoreleasePool alloc] init]; t = (double)cv::getTickCount(); for (int i = 0; i < times; i++) { cv::Mat tempMat = [testImage CVGrayscaleMat]; } t = 1000 * ((double)cv::getTickCount() - t) / cv::getTickFrequency() / times; [pool release]; NSLog(@"UIImage to grayscale cv::Mat: %gms", t); //-------------------------------- // Convert from cv::Mat to UIImage cv::Mat testMat = [testImage CVMat]; t = (double)cv::getTickCount(); for (int i = 0; i < times; i++) { UIImage *tempImage = [[UIImage alloc] initWithCVMat:testMat]; [tempImage release]; } t = 1000 * ((double)cv::getTickCount() - t) / cv::getTickFrequency() / times; NSLog(@"cv::Mat to UIImage: %gms", t); // Process test image and force update of UI _lastFrame = testMat; [self sliderChanged:nil]; } - (IBAction)capture:(id)sender { if (_videoCapture && _videoCapture->grab()) { (*_videoCapture) >> _lastFrame; [self processFrame]; } else { NSLog(@"Failed to grab frame"); } } - (void)processFrame { double t = (double)cv::getTickCount(); cv::Mat grayFrame, output; // Convert captured frame to grayscale cv::cvtColor(_lastFrame, grayFrame, cv::COLOR_RGB2GRAY); // Perform Canny edge detection using slide values for thresholds cv::Canny(grayFrame, output, _lowSlider.value * kCannyAperture * kCannyAperture, _highSlider.value * kCannyAperture * kCannyAperture, kCannyAperture); t = 1000 * ((double)cv::getTickCount() - t) / cv::getTickFrequency(); // Display result self.imageView.image = [UIImage imageWithCVMat:output]; self.elapsedTimeLabel.text = [NSString stringWithFormat:@"%.1fms", t]; }

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• Android AlertDialog wait for result in calling activity

  - by insanesam

  I am trying to use an AlertDialog in my app to select the quantity of an item. The problem is that the activity that calls the AlertDialog doesn't wait for it to update the item before it adds it to the SQLite Database and change intents. At the moment, the QuantitySelector (AlertDialog) appears, then disappears straight away and changes the MealActivity class (which is just a ListView that reads from the database) through the intent change with an update to the database with quantity 0. I need the Activity to wait for the AlertDialog to close before it updates the database. What would be the correct way of implementing this? Here is some code for you: QuantitySelector (which runs the alertdialog): public class QuantitySelector{ protected static final int RESULT_OK = 0; private Context _context; private DatabaseHandler db; private HashMap<String, Double> measures; private Item item; private View v; private EditText quan; private NumberPicker pick; private int value; private Quantity quantity; /** * Function calls the quantity selector AlertDialog * @param _c: The application context * @param item: The item to be added to consumption * @return The quantity that is consumed */ public void select(Context _c, Item item, Quantity quantity){ this._context = _c; this.item = item; this.quantity = quantity; db = new DatabaseHandler(_context); //Get the measures to display createData(); //Set up the custom view LayoutInflater inflater = LayoutInflater.from(_context); v = inflater.inflate(R.layout.quantity_selector, null); //Set up the input fields quan = (EditText) v.findViewById(R.id.quantityNumber); pick = (NumberPicker) v.findViewById(R.id.numberPicker1); //Set up the custom measures into pick pick.setMaxValue(measures.size()-1); pick.setDisplayedValues(measures.keySet().toArray(new String[0])); //Start the alert dialog runDialog(); } public void createData(){ measures = new HashMap<String, Double>(); //Get the measurements from the database if(item!=null){ measures.putAll(db.getMeasures(item)); } //Add grams as the default measurement if(!measures.keySet().contains("grams")){ //Add grams as a standard measure measures.put("grams", 1.0); } } public void runDialog(){ AlertDialog dialog = new AlertDialog.Builder(_context).setTitle("Select Quantity") .setView(v) .setPositiveButton("OK", new DialogInterface.OnClickListener() { public void onClick(DialogInterface dialog, int whichButton) { //Change the consumption to the new quantity if(!quan.getText().toString().matches("")){ value = Integer.parseInt(quan.getText().toString()); //Check if conversion from other units is needed String s[] = pick.getDisplayedValues(); String a = s[pick.getValue()]; //Convert the chosen measure back to grams if(!a.equals("grams")){ for(String m : measures.keySet()){ if(m==a){ value = (int) (value * measures.get(m)); } } } } quantity.setQuantity(value); dialog.dismiss(); } }) .setNegativeButton("Cancel", null).create(); dialog.show(); } } The method from favouritesAdapter (which calls the alertdialog): add.setOnClickListener(new OnClickListener(){ public void onClick(View arg0) { QuantitySelector q = new QuantitySelector(); Quantity quan = new Quantity(); q.select(_context, db.getItem(p.getID()), quan); db.addConsumption(p.getID(), p.getFavouriteShortName(), quan.getQuantity(), "FAVOURITE"); Intent intent = new Intent(_context,MealActivity.class); _context.startActivity(intent); } }); All help is appreciated :)

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• WCF timedout waiting for System.Diagnostics.Process to finish

  - by Bartek

  Dear All, We have a WCF Service deployed on Windows Server 2003 that handles file transfers. When file is in Unix format, I am converting it to Dos format in the initialization stage using System.Diagnostics.Process (.WaitForExit()). Client calls the service: obj_DataSenderService = New DataSendClient() obj_DataSenderService.InnerChannel.OperationTimeout = New TimeSpan(0, System.Configuration.ConfigurationManager.AppSettings("DatasenderServiceOperationTimeout"), 0) str_DataSenderGUID = obj_DataSenderService.Initialize(xe_InitDetails.GetXMLNode) This works fine, however for large files the conversion takes more than 10 minutes and I am getting exception: A first chance exception of type 'System.ServiceModel.CommunicationException' occurred in mscorlib.dll Additional information: The socket connection was aborted. This could be caused by an error processing your message or a receive timeout being exceeded by the remote host, or an underlying network resource issue. Local socket timeout was '00:59:59.8749992'. I tried configuring both client: <system.serviceModel> <bindings> <netTcpBinding> <binding name="NetTcpBinding_IDataSend" closeTimeout="01:00:00" openTimeout="01:00:00" receiveTimeout="01:00:00" sendTimeout="01:00:00" transactionFlow="false" transferMode="Buffered" transactionProtocol="OleTransactions" hostNameComparisonMode="StrongWildcard" listenBacklog="10" maxBufferPoolSize="524288" maxBufferSize="65536" maxConnections="10" maxReceivedMessageSize="65536"> <readerQuotas maxDepth="32" maxStringContentLength="8192" maxArrayLength="16384" maxBytesPerRead="4096" maxNameTableCharCount="16384" /> <reliableSession ordered="true" inactivityTimeout="00:10:00" enabled="false" /> <security mode="None"> <transport clientCredentialType="Windows" protectionLevel="EncryptAndSign" /> <message clientCredentialType="Windows" /> </security> </binding> </netTcpBinding> </bindings> <client> <endpoint address="net.tcp://localhost:4000/DataSenderEndPoint" binding="netTcpBinding" bindingConfiguration="NetTcpBinding_IDataSend" contract="IDataSend" name="NetTcpBinding_IDataSend"> <identity> <servicePrincipalName value="host/localhost" /> <!--<servicePrincipalName value="host/axopwrapp01.Corp.Acxiom.net" />--> </identity> </endpoint> </client> </system.serviceModel> And service: <system.serviceModel> <bindings> <netTcpBinding> <binding name="NetTcpBinding_IDataSend" closeTimeout="01:00:00" openTimeout="01:00:00" receiveTimeout="01:00:00" sendTimeout="01:00:00" transactionFlow="false" transferMode="Buffered" transactionProtocol="OleTransactions" hostNameComparisonMode="StrongWildcard" listenBacklog="10" maxBufferPoolSize="524288" maxBufferSize="65536" maxConnections="10" maxReceivedMessageSize="65536"> </binding> </netTcpBinding> </bindings> </system.serviceModel> but without luck. In the Service trace viewer I can see: Close process timed out waiting for service dispatch to complete. with stack trace: System.ServiceModel.ServiceChannelManager.CloseInput(TimeSpan timeout) System.ServiceModel.Dispatcher.InstanceContextManager.CloseInput(TimeSpan timeout) System.ServiceModel.ServiceHostBase.OnClose(TimeSpan timeout) System.ServiceModel.Channels.CommunicationObject.Close(TimeSpan timeout) System.ServiceModel.Channels.CommunicationObject.Close() DataSenderService.DataSender.OnStop() System.ServiceProcess.ServiceBase.DeferredStop() System.Runtime.Remoting.Messaging.StackBuilderSink._PrivateProcessMessage(IntPtr md, Object[] args, Object server, Int32 methodPtr, Boolean fExecuteInContext, Object[]& outArgs) System.Runtime.Remoting.Messaging.StackBuilderSink.PrivateProcessMessage(RuntimeMethodHandle md, Object[] args, Object server, Int32 methodPtr, Boolean fExecuteInContext, Object[]& outArgs) System.Runtime.Remoting.Messaging.StackBuilderSink.AsyncProcessMessage(IMessage msg, IMessageSink replySink) System.Runtime.Remoting.Proxies.AgileAsyncWorkerItem.DoAsyncCall() System.Runtime.Remoting.Proxies.AgileAsyncWorkerItem.ThreadPoolCallBack(Object o) System.Threading._ThreadPoolWaitCallback.WaitCallback_Context(Object state) System.Threading.ExecutionContext.runTryCode(Object userData) System.Runtime.CompilerServices.RuntimeHelpers.ExecuteCodeWithGuaranteedCleanup(TryCode code, CleanupCode backoutCode, Object userData) System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state) System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state) System.Threading._ThreadPoolWaitCallback.PerformWaitCallbackInternal(_ThreadPoolWaitCallback tpWaitCallBack) System.Threading._ThreadPoolWaitCallback.PerformWaitCallback(Object state) Many thanks Bartek

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• Problem saving as png a SVG generated by Raphael JS in a canvas

  - by ClemDesm

  Hi fellow SOers, I'm trying to convert a SVG generated by Raphael JS (and the user, since you can drag and rotate the images). I followed this Conversion of SVG to Jpeg but still can't get it. It must be easy but I can't put my finger on what I get wrong. I got my svg in a div with #ec as id and the canvas's one is #canvas. function saveDaPicture(){ var img = document.getElementById('canvas').toDataURL("image/png"); $('body').append('<img src="'+img+'"/>'); } $('#save').click(function(){ var svg = $('#ec').html(); alert(svg); canvg('canvas', svg, {renderCallback: saveDaPicture(), ignoreMouse: true, ignoreAnimation: true}); }); The alert gives me : <svg xmlns="http://www.w3.org/2000/svg" version="1.1" width="600" height="512"> <desc>Created with Raphael</desc> <defs></defs> <image x="0" y="0" width="300" height="512" preserveAspectRatio="none" href="imageurl.jpg"></image> <rect x="168" y="275" width="52" height="70" r="0" rx="0" ry="0" fill="none" stroke="#000" stroke-dasharray="8,3" transform="rotate(21.91207728 194 310)" style="opacity: 1; display: none; " opacity="1"></rect> <circle cx="50" cy="50" r="50" fill="none" stroke="#000"></circle> <image x="358" y="10" width="39" height="138" preserveAspectRatio="none" href="imageurl2.png" style="cursor: move; "></image> <image x="397" y="10" width="99" height="153" preserveAspectRatio="none" href="imageurl3.png" style="cursor: move; "></image> <image x="184" y="286" width="10" height="10" preserveAspectRatio="none" href="imageurl4.png" style="cursor: pointer; opacity: 1; display: none; " opacity="1"></image> <image x="204" y="286" width="10" height="10" preserveAspectRatio="none" href="imageurl5.png" style="cursor: pointer; opacity: 1; display: none; " opacity="1"></image> <image x="170" y="277" width="48" height="66" preserveAspectRatio="none" href="imageurl6.png" style="cursor: move; opacity: 1; " r="50" opacity="1" transform="rotate(21.91207728 194 310)"></image> </svg> which is the xml of the svg and if I believe canvg documentation, it's good. Anyway, with this code, the variable img, which should have the converted image data, got the data of an empty png with the dimensions of the svg. The only thing I guess is that the svg generated by Raphael JS is not well formated for canvg (like, href of image should be xlink:href if I follow the W3C recommandations ) Anyone got an idea on this problem ? :D

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• handling filename* parameters with spaces via RFC 5987 results in '+' in filenames

  - by Peter Friend

  I have some legacy code I am dealing with (so no I can't just use a URL with an encoded filename component) that allows a user to download a file from our website. Since our filenames are often in many different languages they are all stored as UTF-8. I wrote some code to handle the RFC5987 conversion to a proper filename* parameter. This works great until I have a filename with non-ascii characters and spaces. Per RFC, the space character is not part of attr_char so it gets encoded as %20. I have new versions of Chrome as well as Firefox and they are all converting to %20 to + on download. I have tried not encoding the space and putting the encoded filename in quotes and get the same result. I have sniffed the response coming from the server to verify that the servlet container wasn't mucking with my headers and they look correct to me. The RFC even has examples that contain %20. Am I missing something, or do all of these browsers have a bug related to this? Many thanks in advance. The code I use to encode the filename is below. Peter public static boolean bcsrch(final char[] chars, final char c) { final int len = chars.length; int base = 0; int last = len - 1; /* Last element in table */ int p; while (last >= base) { p = base + ((last - base) >> 1); if (c == chars[p]) return true; /* Key found */ else if (c < chars[p]) last = p - 1; else base = p + 1; } return false; /* Key not found */ } public static String rfc5987_encode(final String s) { final int len = s.length(); final StringBuilder sb = new StringBuilder(len << 1); final char[] digits = {'0','1','2','3','4','5','6','7','8','9','A','B','C','D','E','F'}; final char[] attr_char = {'!','#','$','&','\'','+','-','.','0','1','2','3','4','5','6','7','8','9','A','B','C','D','E','F','G','H','I','J','K','L','M','N','O','P','Q','R','S','T','U','V','W','X','Y','Z','^','_','a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z','|', '~'}; for (int i = 0; i < len; ++i) { final char c = s.charAt(i); if (bcsrch(attr_char, c)) sb.append(c); else { final char[] encoded = {'%', 0, 0}; encoded[1] = digits[0x0f & (c >>> 4)]; encoded[2] = digits[c & 0x0f]; sb.append(encoded); } } return sb.toString(); } Update Here is a screen shot of the download dialog I get for a file with Chinese characters with spaces as mentioned in my comment.

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• Plotting points so that they do not overlap if they have the same co-ordinates

  - by betamax

  Hi everyone, I have a function that takes longitude and latitude and converts it to x and y to be plotted. The conversion to X and Y is working fine and that is not what I have the problem with. I want to ensure that two points are not plotted in the same place. In one set of results there are about 30 on top of each other (because they have the same latitude and longitude), this number could be a lot larger. At the moment I am trying to achieve this by moving points to the left, right, top or bottom of the point to make a square. Once a square made up of points has been drawn, then moving to the next row on and drawing another square of points around the previous square. The code is Javascript but it is very generic so I guess it's slightly irrelevant. My code is as follows: var prevLong, prevLat, rand = 1, line = 1, spread = 8, i = 0; function plot_points(long, lat){ // CODE HERE TO CONVERT long and lat into x and y // System to not overlap the points if((prevLat == lat) && (prevLong == long)) { if(rand==1) { x += spread*line; } else if(rand==2) { x -= spread*line; } else if(rand==3) { y += spread*line; } else if(rand==4) { y -= spread*line; } else if(rand==5) { x += spread*line; y += spread*line; } else if(rand==6) { x -= spread*line; y -= spread*line; } else if(rand==7) { x += spread*line; y -= spread*line; } else if(rand==8) { x -= spread*line; y += spread*line; // x = double } else if(rand==9) { x += spread*line; y += spread; } else if(rand==10) { x += spread; y += spread*line; } else if(rand==11) { x -= spread*line; y -= spread; } else if(rand==12) { x -= spread; y -= spread*line; } else if(rand==13) { x += spread*line; y -= spread; } else if(rand==14) { x += spread; y -= spread*line; } else if(rand==15) { x += spread*line; y -= spread; } else if(rand==16) { x += spread; y -= spread*line; } else if(rand==17) { x -= spread*line; y += spread; } else if(rand==18) { x -= spread; y += spread*line; } else if(rand==19) { x -= spread*line; y += spread; } else if(rand==20) { x -= spread; y += spread*line; } if(rand == 20) {rand = 1; line++; } else { rand++; } i++ } else { line = 1; i = 0; } prevLat = latitude; prevLong = longitude; return [x,y]; } This is the output: It isn't working correctly and I don't even know if I am approaching the problem in a correct way at all. Has anyone had to do this before? What method would you suggest?

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• Java multiple class compositing and boiler plate reduction

  - by h2g2java

  We all know why Java does/should not have multiple inheritance. So this is not questioning about what has already been debated till-cows-come-home. This discusses what we would do when we wish to create a class that has the characteristics of two or more other classes. Probably, most of us would do this to "inherit" from three classes. For simplicity, I left out the constructor.: class Car extends Vehicle { final public Transport transport; final public Machine machine; } So that, Car class directly inherits methods and objects of Vehicle class, but would have to refer to transport and machine explicitly to refer to objects instantiated in Transport and Machine. Car car = new Car(); car.drive(); // from Vehicle car.transport.isAmphibious(); // from Transport car.machine.getCO2Footprint(); // from Machine I thought this was a good idea until when I encounter frameworks that require setter and getter methods. For example, the XML <Car amphibious='false' footPrint='1000' model='Fordstatic999'/> would look for the methods setAmphibious(..), setFootPrint(..) and setModel(..). Therefore, I have to project the methods from Transport and Machine classes class Car extends Vehicle { final public Transport transport; final public Machine machine; public void setAmphibious(boolean b){ this.transport.setAmphibious(b); } public void setFootPrint(String fp){ this.machine.setFootPrint(fp); } } This is OK, if there were just a few characteristics. Right now, I am trying to adapt all of SmartGWT into GWT UIBinder, especially those classes that are not a GWT widget. There are lots of characteristics to project. Wouldn't it be nice if there exists some form of annotation framework that is like this: class Car extends Vehicle @projects {Transport @projects{Machine @projects Guzzler}} { /* No need to explicitly instantiate Transport, Machine or Guzzler */ .... } Where, in case of common names of characteristics exist, the characteristics of Machine would take precedence Guzzler's, and Transport's would have precedence over Machine's, and Vehicle's would have precedence over Transport's. The annotation framework would then instantiate Transport, Machine and Guzzler as hidden members of Car and expand to break-out the protected/public characteristics, in the precedence dictated by the @project annotation sequence, into actual source code or into byte-code. Preferably into byte-code. So that the setFootPrint method is found in both Machine and Guzzler, only that of Machine's would be projected. Questions: Don't you think this is a good idea to have such a framework? Does such a framework already exist? Tell me where/what. Is there an eclipse plugin that does it? Is there a proposal or plan anywhere that you know about such an annotation framework? It would be wonderful too, if the annotation/plugin framework lets me specify that boolean, int, or whatever else needs to be converted from String and does the conversion/parsing for me too. Please advise, somebody. I hope wording of my question was clear enough. Thx. Edited: To avoid OO enthusiasts jumping to conclusion, I have renamed the title of this question.

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• Where do I start ?

  - by Panthe

  Brief History: Just graduated high school, learned a bit of python and C++, have no friends with any helpful computer knowledge at all. Out of anyone i met in my school years I was probably the biggest nerd, but no one really knew. I consider my self to have a vast amount of knowledge on computers and tech then the average person. built/fixed tons of computers, and ability to troubleshoot pretty much any problem I came across. Now that high school is over, Ive really been thinking about my career. Loving, living computers for the past 15 years of my life I decided to take my ability's and try to learn computer programming, why I didn't start earlier I don't know, seems to be big mistake on my part... Doing some research I concluded that Python was the first programming language I should learn, since it was high level and easier to understand then C++ and Java. I also knew that to become good at what I did I needed to know more then just 2 or 3 languages, which didn't seem like a big problem considering once I learned the way Python worked, mainly syntax changed, and the rest would come naturally. I watched a couple of youtube videos, downloaded some book pdf's and snooped around from some tutorials here and there to get the hang of what to do. A two solid weeks had passed of trying to understand the syntax, create small programs that used the basic functions and understanding how it worked, I think i have got the hang of it. It breaks down into what ive been dealing with all this time (although i kinda knew) is that, input,output, loops, functions and other things derived from 0's and 1's storing data and recalling it, ect. (A VERY BASIC IDEA). Ive been able to create small programs, Hangman, file storing, temperature conversion, Caeser Cipher decode/encoding, Fibonacci Sequence and more, which i can create and understand how each work. Being 2 weeks into this, I have learned alot. Nothing at all compared to what i should be learning in the years to come if i get a grip on what I'm doing. While doing these programs I wont stop untill I've done doing a practice problem on a book, which embarresing enough will take me a couple hour depending on the complexity of it. I absolutly will not put aside the challenge until its complete, WHICH CAN BE EXTREMELY DRAINING, ive tried most problems without cheating and reached success, which makes me feel extremely proud of my self after completing something after much trial and error. After all this I have met the demon, alogrithm's which seem to be key to effiecent code. I cant seem to rap my head around some of the computer codes people put out there using numbers, and sometimes even basic functions, I have been able to understand them after a while but i know there are alot more complex things to come, considering my self smart, functions that require complex codes, actually hurt my brain. NOTHING EVER IN LIFE HURT MY BRAIN....... not even math classes in highschool, trying to understand some of the stuff people put out there makes me feel like i have a mental disadvantage lol... i still walk forward though, crossing my fingers that the understanding will come with time. Sorry if is this is long i just wish someone takes all these things into consideration when answering my question. even through all these downsides im still pushing through and continuing to try and get good at this, i know reading these tutorials wont make me any good unless i can become creative and make my own, understand other peoples programs, so this leads me to the simple question i could have asked in the beginning..... WHERE IN THE WORLD DO I START ? Ive been trying to find out how to understand some of the open source projects, how i can work with experianced coders to learn from them and help them, but i dont think thats even possible by the way how far people's knowledge is compared to me, i have no freinds who i can learn from, can someone help me and guide me into the right direction.. i have a huge motivation to get good at coding, anything information would be extremely helpful

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• Adding to database with multiple text boxes

  - by kira423

  What I am trying to do with this script is allow users to update a url for their websites, and since each user isn't going to have the same amount of websites is is hard for me to just add $_POST['website'] for each of these. Here is the script <?php include("config.php"); include("header.php"); include("functions.php"); if(!isset($_SESSION['username']) && !isset($_SESSION['password'])){ header("Location: pubs.php"); } $getmember = mysql_query("SELECT * FROM `publishers` WHERE username = '".$_SESSION['username']."'"); $info = mysql_fetch_array($getmember); $getsites = mysql_query("SELECT * FROM `websites` WHERE publisher = '".$info['username']."'"); $postback = $_POST['website']; $webname = $_POST['webid']; if($_POST['submit']){ var_dump( $_POST['website'] ); $update = mysql_query("UPDATE `websites` SET `postback` = '$postback' WHERE name = '$webname'"); } print" <div id='center'> <span id='tools_lander'><a href='export.php'>Export Campaigns</a></span> <div id='calendar_holder'> <h3>Please define a postback for each of your websites below. The following variables should be used when creating your postback.<br /> cid = Campaign ID<br /> sid = Sub ID<br /> rate = Campaign Rate<br /> status = Status of Lead. 1 means payable 2 mean reversed<br /> A sample postback URL would be <br /> http://www.example.com/postback.php?cid=#cid&sid=#sid&rate=#rate&status=#status</h3> <table class='balances' align='center'> <form method='POST' action=''>"; while($website = mysql_fetch_array($getsites)){ print" <tr> <input type ='hidden' name='webid' value='".$website['id']."' /> <td style='font-weight:bold;'>".$website['name']."'s Postback:</td> <td><input type='text' style='width:400px;' name='website[]' value='".$website['postback']."' /></td> </tr>"; } print" <td style='float:right;position:relative;left:150px;'><input type='submit' name='submit' style='font-size:15px;height:30px;width:100px;' value='Submit' /></td> </form> </table> </div>"; include("footer.php"); ?> What I am attempting to do insert the what is inputted in the text boxes to their corresponding websites, and I cannot think of any other way to do it, and this obviously does not works and returns a notice stating Array to string conversion If there is a more logical way to do this please let me know.

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• How to convert image to bitmap code for bluetooth print in iphone

  - by John Patel

  I am interested to print image from iPhone programmatically using bluetooth printer device. In one of the sample code I have implemented code for Text print but in that sample I am not getting how to convert image into format, like unsigned char buffer3[796]={ 0x55 , 0x66 , 0x77 , 0x88 , 0x44 , 0x1B , 0x58 , 0x31 , 0x19, 0x20, 0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x80 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x01 ,0xC0 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x01 ,0x80 ,0x00 ,0x03 ,0x60 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x03 ,0xA0 ,0x00 ,0x07 ,0xB0 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x05 ,0x60 ,0x00 ,0x07 ,0xD8 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x05 ,0xA0 ,0x00 ,0x13 ,0xEC ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x04 ,0x20 ,0x00 ,0x29 ,0xF4 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x03 ,0xC0 ,0x00 ,0x64 ,0xF9 ,0x00 ,0x0F ,0xFF ,0x9C ,0x01 ,0xC0 ,0x19 ,0xFF ,0xC0 ,0x7F ,0xFC ,0x7F ,0xF9 ,0xC0 ,0x3D ,0xFF ,0xF1 ,0xFF ,0xE3 ,0xFF ,0xC0 ,0x00 ,0x00 ,0xF2 ,0x73 ,0x80 ,0x0F ,0xFF ,0x9C ,0x01 ,0xC0 ,0x19 ,0xFF ,0xC0 ,0x7F ,0xFE ,0x7F ,0xFD ,0xE0 ,0x3D ,0xFF ,0xF1 ,0xFF ,0xE3 ,0xFF ,0xC0 ,0x00 ,0x00 ,0x79 ,0x26 ,0xC0 ,0x0F ,0xFF ,0xDC ,0x01 ,0xC0 ,0x19 ,0xFF ,0xC0 ,0x7F ,0xFE ,0xFF ,0xFD ,0xF0 ,0x7D ,0xFF ,0xFB ,0xFF ,0xF7 ,0xFF ,0xE0 ,0x00 ,0x03 ,0x3C ,0x8F ,0x60 ,0x0C ,0x01 ,0xDC ,0x01 ,0xC0 ,0x19 ,0x80 ,0x00 ,0x70 ,0x0E ,0xE0 ,0x1D ,0xF0 ,0x7D ,0x80 ,0x3B ,0x80 ,0x77 ,0x00 ,0xE0 ,0x00 ,0x04 ,0x9E ,0x8F ,0xB0 ,0x0E ,0x01 ,0xDC ,0x01 ,0xC0 ,0x19 ,0x80 ,0x00 ,0x70 ,0x0E ,0xE0 ,0x1D ,0xF8 ,0xFD ,0x80 ,0x33 ,0x80 ,0x77 ,0x00 ,0xE0 ,0x00 ,0x0E ,0x4F ,0x27 ,0xD8 ,0x0F ,0xFF ,0x9C ,0x01 ,0xC0 ,0x19 ,0xFF ,0xC0 ,0x7F ,0xFC ,0xE0 ,0x1D ,0xF9 ,0xFD ,0xFF ,0xF3 ,0x80 ,0x77 ,0x00 ,0xE0 ,0x00 ,0x0F ,0x26 ,0x53 ,0xC8 ,0x0F ,0xFF ,0x9C ,0x01 ,0xC0 ,0x19 ,0xFF ,0xC0 ,0x7F ,0xFC ,0xEF ,0xFD ,0xDD ,0xDD ,0xFF ,0xF3 ,0x80 ,0x77 ,0x00 ,0xE0 ,0x00 ,0x07 ,0x90 ,0xC9 ,0xF0 ,0x0F ,0xFF ,0xDC ,0x01 ,0xC0 ,0x19 ,0xFF ,0xC0 ,0x7F ,0xFE ,0xEF ,0xFD ,0xDF ,0x9D ,0xFF ,0xFB ,0x80 ,0x77 ,0x00 ,0xE0 ,0x00 ,0x03 ,0xC9 ,0xE4 ,0xE0 ,0x0C ,0x00 ,0xDC ,0x01 ,0xC0 ,0x19 ,0x80 ,0x00 ,0x70 ,0x06 ,0xE7 ,0xFD ,0xCF ,0x9D ,0x80 ,0x3B ,0x80 ,0x77 ,0x00 ,0xE0 ,0x00 ,0x01 ,0xF0 ,0xF2 ,0x40 ,0x0E ,0x01 ,0xDC ,0x00 ,0xC0 ,0x19 ,0x80 ,0x00 ,0x70 ,0x0E ,0xE0 ,0x1D ,0xCF ,0x1D ,0x80 ,0x3B ,0x80 ,0x77 ,0x00 ,0xE0 ,0x00 ,0x00 ,0xE6 ,0x79 ,0x00 ,0x0F ,0xFF ,0xDF ,0xFC ,0xFF ,0xF9 ,0xFF ,0xC0 ,0x7F ,0xFE ,0xE0 ,0x1D ,0xC7 ,0x1D ,0xFF ,0xFB ,0xFF ,0xF7 ,0xFF ,0xE0 ,0x00 ,0x00 ,0x49 ,0x3D ,0x00 ,0x0F ,0xFF ,0x9F ,0xFC ,0xFF ,0xF9 ,0xFF ,0xC0 ,0x7F ,0xFE ,0xE0 ,0x1D ,0xC2 ,0x1D ,0xFF ,0xF1 ,0xFF ,0xE3 ,0xFF ,0xC0 ,0x00 ,0x00 ,0x1C ,0x9E ,0x00 ,0x0F ,0xFF ,0x1F ,0xFC ,0x7F ,0xE1 ,0xFF ,0xC0 ,0x7F ,0xFC ,0xE0 ,0x1D ,0xC0 ,0x1D ,0xFF ,0xE0 ,0xFF ,0xC1 ,0xFF ,0x80 ,0x00 ,0x00 ,0x1E ,0x4C ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x0F ,0x20 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x07 ,0x90 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x03 ,0xE0 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x01 ,0xC0 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x80 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 }; //[self addLabel:@"buffer3 is selected"]; [[session outputStream] write:(const uint8_t *)buffer3 maxLength:796];//send print package*/ This is sample code for Image print I am not able to print any other image because I am not having idea how to convert UIImage or NSData to the below mentioned Bit code. If any proper step by step method to do Image to bitmap conversion, then please let me know this.

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• How to play audio in Java Application

  - by user577829

  I'm making a java application and I need to play audio. I'm playing mainly small sound files of my cannon firing (its a cannon shooting game) and the projectiles exploding, though I plan on having looping background music. I have found two different methods to accomplish this, but both don't work how I want. The first method is literally a method: public void playSoundFile(File file) {//http://java.ittoolbox.com/groups/technical-functional/java-l/sound-in-an-application-90681 try { //get an AudioInputStream AudioInputStream ais = AudioSystem.getAudioInputStream(file); //get the AudioFormat for the AudioInputStream AudioFormat audioformat = ais.getFormat(); System.out.println("Format: " + audioformat.toString()); System.out.println("Encoding: " + audioformat.getEncoding()); System.out.println("SampleRate:" + audioformat.getSampleRate()); System.out.println("SampleSizeInBits: " + audioformat.getSampleSizeInBits()); System.out.println("Channels: " + audioformat.getChannels()); System.out.println("FrameSize: " + audioformat.getFrameSize()); System.out.println("FrameRate: " + audioformat.getFrameRate()); System.out.println("BigEndian: " + audioformat.isBigEndian()); //ULAW format to PCM format conversion if ((audioformat.getEncoding() == AudioFormat.Encoding.ULAW) || (audioformat.getEncoding() == AudioFormat.Encoding.ALAW)) { AudioFormat newformat = new AudioFormat(AudioFormat.Encoding.PCM_SIGNED, audioformat.getSampleRate(), audioformat.getSampleSizeInBits() * 2, audioformat.getChannels(), audioformat.getFrameSize() * 2, audioformat.getFrameRate(), true); ais = AudioSystem.getAudioInputStream(newformat, ais); audioformat = newformat; } //checking for a supported output line DataLine.Info datalineinfo = new DataLine.Info(SourceDataLine.class, audioformat); if (!AudioSystem.isLineSupported(datalineinfo)) { //System.out.println("Line matching " + datalineinfo + " is not supported."); } else { //System.out.println("Line matching " + datalineinfo + " is supported."); //opening the sound output line SourceDataLine sourcedataline = (SourceDataLine) AudioSystem.getLine(datalineinfo); sourcedataline.open(audioformat); sourcedataline.start(); //Copy data from the input stream to the output data line int framesizeinbytes = audioformat.getFrameSize(); int bufferlengthinframes = sourcedataline.getBufferSize() / 8; int bufferlengthinbytes = bufferlengthinframes * framesizeinbytes; byte[] sounddata = new byte[bufferlengthinbytes]; int numberofbytesread = 0; while ((numberofbytesread = ais.read(sounddata)) != -1) { int numberofbytesremaining = numberofbytesread; sourcedataline.write(sounddata, 0, numberofbytesread); } } } catch (Exception e) { e.printStackTrace(); } } The problem with this is that my entire program stops until the sound file is finished, or at least nearly finished. The second method is this: File file = new File("Launch1.wav"); AudioClip clip; try { clip = JApplet.newAudioClip(file.toURL()); clip.play(); } catch (Exception e) { e.getMessage(); } The problem I have here is that every time the sound file ends early or doesn't play at all depending on where I place the code. Is their any way to play sound without the above mentioned problems? Am I doing something wrong? Any help is greatly appreciated.

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• Make interchangeable class types via pointer casting only, without having to allocate any new objects?

  - by HostileFork

  UPDATE: I do appreciate "don't want that, want this instead" suggestions. They are useful, especially when provided in context of the motivating scenario. Still...regardless of goodness/badness, I've become curious to find a hard-and-fast "yes that can be done legally in C++11" vs "no it is not possible to do something like that". I want to "alias" an object pointer as another type, for the sole purpose of adding some helper methods. The alias cannot add data members to the underlying class (in fact, the more I can prevent that from happening the better!) All aliases are equally applicable to any object of this type...it's just helpful if the type system can hint which alias is likely the most appropriate. There should be no information about any specific alias that is ever encoded in the underlying object. Hence, I feel like you should be able to "cheat" the type system and just let it be an annotation...checked at compile time, but ultimately irrelevant to the runtime casting. Something along these lines: Node<AccessorFoo>* fooPtr = Node<AccessorFoo>::createViaFactory(); Node<AccessorBar>* barPtr = reinterpret_cast< Node<AccessorBar>* >(fooPtr); Under the hood, the factory method is actually making a NodeBase class, and then using a similar reinterpret_cast to return it as a Node<AccessorFoo>*. The easy way to avoid this is to make these lightweight classes that wrap nodes and are passed around by value. Thus you don't need casting, just Accessor classes that take the node handle to wrap in their constructor: AccessorFoo foo (NodeBase::createViaFactory()); AccessorBar bar (foo.getNode()); But if I don't have to pay for all that, I don't want to. That would involve--for instance--making a special accessor type for each sort of wrapped pointer (AccessorFooShared, AccessorFooUnique, AccessorFooWeak, etc.) Having these typed pointers being aliased for one single pointer-based object identity is preferable, and provides a nice orthogonality. So back to that original question: Node<AccessorFoo>* fooPtr = Node<AccessorFoo>::createViaFactory(); Node<AccessorBar>* barPtr = reinterpret_cast< Node<AccessorBar>* >(fooPtr); Seems like there would be some way to do this that might be ugly but not "break the rules". According to ISO14882:2011(e) 5.2.10-7: An object pointer can be explicitly converted to an object pointer of a different type.70 When a prvalue v of type "pointer to T1" is converted to the type "pointer to cv T2", the result is static_cast(static_cast(v)) if both T1 and T2 are standard-layout types (3.9) and the alignment requirements of T2 are no stricter than those of T1, or if either type is void. Converting a prvalue of type "pointer to T1" to the type "pointer to T2" (where T1 and T2 are object types and where the alignment requirements of T2 are no stricter than those of T1) and back to its original type yields the original pointer value. The result of any other such pointer conversion is unspecified. Drilling into the definition of a "standard-layout class", we find: has no non-static data members of type non-standard-layout-class (or array of such types) or reference, and has no virtual functions (10.3) and no virtual base classes (10.1), and has the same access control (clause 11) for all non-static data members, and has no non-standard-layout base classes, and either has no non-static data member in the most-derived class and at most one base class with non-static data members, or has no base classes with non-static data members, and has no base classes of the same type as the first non-static data member. Sounds like working with something like this would tie my hands a bit with no virtual methods in the accessors or the node. Yet C++11 apparently has std::is_standard_layout to keep things checked. Can this be done safely? Appears to work in gcc-4.7, but I'd like to be sure I'm not invoking undefined behavior.

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• Defend PHP; convince me it isn't horrible

  - by Jason L

  I made a tongue-in-cheek comment in another question thread calling PHP a terrible language and it got down-voted like crazy. Apparently there are lots of people here who love PHP. So I'm genuinely curious. What am I missing? What makes PHP a good language? Here are my reasons for disliking it: PHP has inconsistent naming of built-in and library functions. Predictable naming patterns are important in any design. PHP has inconsistent parameter ordering of built-in functions, eg array_map vs. array_filter which is annoying in the simple cases and raises all sorts of unexpected behaviour or worse. The PHP developers constantly deprecate built-in functions and lower-level functionality. A good example is when they deprecated pass-by-reference for functions. This created a nightmare for anyone doing, say, function callbacks. A lack of consideration in redesign. The above deprecation eliminated the ability to, in many cases, provide default keyword values for functions. They fixed this in PHP 5, but they deprecated the pass-by-reference in PHP 4! Poor execution of name spaces (formerly no name spaces at all). Now that name spaces exist, what do we use as the dereference character? Backslash! The character used universally for escaping, even in PHP! Overly-broad implicit type conversion leads to bugs. I have no problem with implicit conversions of, say, float to integer or back again. But PHP (last I checked) will happily attempt to magically convert an array to an integer. Poor recursion performance. Recursion is a fundamentally important tool for writing in any language; it can make complex algorithms far simpler. Poor support is inexcusable. Functions are case insensitive. I have no idea what they were thinking on this one. A programming language is a way to specify behavior to both a computer and a reader of the code without ambiguity. Case insensitivity introduces much ambiguity. PHP encourages (practically requires) a coupling of processing with presentation. Yes, you can write PHP that doesn't do so, but it's actually easier to write code in the incorrect (from a sound design perspective) manner. PHP performance is abysmal without caching. Does anyone sell a commercial caching product for PHP? Oh, look, the designers of PHP do. Worst of all, PHP convinces people that designing web applications is easy. And it does indeed make much of the effort involved much easier. But the fact is, designing a web application that is both secure and efficient is a very difficult task. By convincing so many to take up programming, PHP has taught an entire subgroup of programmers bad habits and bad design. It's given them access to capabilities that they lack the understanding to use safely. This has led to PHP's reputation as being insecure. (However, I will readily admit that PHP is no more or less secure than any other web programming language.) What is it that I'm missing about PHP? I'm seeing an organically-grown, poorly-managed mess of a language that's spawning poor programmers. So convince me otherwise!

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• How do I learn algorithms?

  - by Panthe

  Brief History: Just graduated high school, learned a bit of python and C++, have no friends with any helpful computer knowledge at all. Out of anyone i met in my school years I was probably the biggest nerd, but no one really knew. I consider my self to have a vast amount of knowledge on computers and tech then the average person. built/fixed tons of computers, and ability to troubleshoot pretty much any problem I came across. Now that high school is over, Ive really been thinking about my career. Loving, living computers for the past 15 years of my life I decided to take my ability's and try to learn computer programming, why I didn't start earlier I don't know, seems to be big mistake on my part... Doing some research I concluded that Python was the first programming language I should learn, since it was high level and easier to understand then C++ and Java. I also knew that to become good at what I did I needed to know more then just 2 or 3 languages, which didn't seem like a big problem considering once I learned the way Python worked, mainly syntax changed, and the rest would come naturally. I watched a couple of youtube videos, downloaded some book pdf's and snooped around from some tutorials here and there to get the hang of what to do. A two solid weeks had passed of trying to understand the syntax, create small programs that used the basic functions and understanding how it worked, I think i have got the hang of it. It breaks down into what ive been dealing with all this time (although i kinda knew) is that, input,output, loops, functions and other things derived from 0's and 1's storing data and recalling it, ect. (A VERY BASIC IDEA). Ive been able to create small programs, Hangman, file storing, temperature conversion, Caeser Cipher decode/encoding, Fibonacci Sequence and more, which i can create and understand how each work. Being 2 weeks into this, I have learned alot. Nothing at all compared to what i should be lear ning in the years to come if i get a grip on what I'm doing. While doing these programs I wont stop untill I've done doing a practice problem on a book, which embarresing enough will take me a couple hour depending on the complexity of it. I absolutly will not put aside the challenge until its complete, WHICH CAN BE EXTREMELY DRAINING, ive tried most problems without cheating and reached success, which makes me feel extremely proud of my self after completing something after much trial and error. After all this I have met the demon, alogrithm's which seem to be key to effiecent code. I cant seem to rap my head around some of the computer codes people put out there using numbers, and sometimes even basic functions, I have been able to understand them after a while but i know there are alot more complex things to come, considering my self smart, functions that require complex codes, actually hurt my brain. NOTHING EVER IN LIFE HURT MY BRAIN....... not even math classes in highschool, trying to understand some of the stuff people put out there makes me feel like i have a mental disadvantage lol... i still walk forward though, crossing my fingers that the understanding will come with time. Sorry if is this is long i just wish someone takes all these things into consideration when answering my question. even through all these downsides im still pushing through and continuing to try and get good at this, i know reading these tutorials wont make me any good unless i can become creative and make my own, understand other peoples programs, so this leads me to the simple question i could have asked in the beginning..... WHERE IN THE WORLD DO I START ? Ive been trying to find out how to understand some of the open source projects, how i can work with experianced coders to learn from them and help them, but i dont think thats even possible by the way how far people's knowledge is compared to me, i have no freinds who i can learn from, can someone help me and guide me into the right direction.. i have a huge motivation to get good at coding, anything information would be extremely helpful

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• Converting OCaml to F#: F# equivelent of Pervasives at_exit

  - by Guy Coder

  I am converting the OCaml Format module to F# and tracked a problem back to a use of the OCaml Pervasives at_exit. val at_exit : (unit -> unit) -> unit Register the given function to be called at program termination time. The functions registered with at_exit will be called when the program executes exit, or terminates, either normally or because of an uncaught exception. The functions are called in "last in, first out" order: the function most recently added with at_exit is called first. In the process of conversion I commented out the line as the compiler did not flag it as being needed and I was not expecting an event in the code. I checked the FSharp.PowerPack.Compatibility.PervasivesModule for at_exit using VS Object Browser and found none. I did find how to run code "at_exit"? and How do I write an exit handler for an F# application? The OCaml line is at_exit print_flush with print_flush signature: val print_flush : (unit -> unit) Also in looking at the use of it during a debug session of the OCaml code, it looks like at_exit is called both at the end of initialization and at the end of each use of a call to the module. Any suggestions, hints on how to do this. This will be my first event in F#. EDIT Here is some of what I have learned about the Format module that should shed some light on the problem. The Format module is a library of functions for basic pretty printer commands of simple OCaml values such as int, bool, string. The format module has commands like print_string, but also some commands to say put the next line in a bounded box, think new set of left and right margins. So one could write: print_string "Hello" or open_box 0; print_string "<<"; open_box 0; print_string "p \/ q ==> r"; close_box(); print_string ">>"; close_box() The commands such as open_box and print_string are handled by a loop that interprets the commands and then decides wither to print on the current line or advance to the next line. The commands are held in a queue and there is a state record to hold mutable values such as left and right margin. The queue and state needs to be primed, which from debugging the test cases against working OCaml code appears to be done at the end of initialization of the module but before the first call is made to any function in the Format module. The queue and state is cleaned up and primed again for the next set of commands by the use of mechanisms for at_exit that recognize that the last matching frame for the initial call to the format modules has been removed thus triggering the call to at_exit which pushes out any remaining command in the queue and re-initializes the queue and state. So the sequencing of the calls to print_flush is critical and appears to be at more than what the OCaml documentation states.

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• Effective optimization strategies on modern C++ compilers

  - by user168715

  I'm working on scientific code that is very performance-critical. An initial version of the code has been written and tested, and now, with profiler in hand, it's time to start shaving cycles from the hot spots. It's well-known that some optimizations, e.g. loop unrolling, are handled these days much more effectively by the compiler than by a programmer meddling by hand. Which techniques are still worthwhile? Obviously, I'll run everything I try through a profiler, but if there's conventional wisdom as to what tends to work and what doesn't, it would save me significant time. I know that optimization is very compiler- and architecture- dependent. I'm using Intel's C++ compiler targeting the Core 2 Duo, but I'm also interested in what works well for gcc, or for "any modern compiler." Here are some concrete ideas I'm considering: Is there any benefit to replacing STL containers/algorithms with hand-rolled ones? In particular, my program includes a very large priority queue (currently a std::priority_queue) whose manipulation is taking a lot of total time. Is this something worth looking into, or is the STL implementation already likely the fastest possible? Along similar lines, for std::vectors whose needed sizes are unknown but have a reasonably small upper bound, is it profitable to replace them with statically-allocated arrays? I've found that dynamic memory allocation is often a severe bottleneck, and that eliminating it can lead to significant speedups. As a consequence I'm interesting in the performance tradeoffs of returning large temporary data structures by value vs. returning by pointer vs. passing the result in by reference. Is there a way to reliably determine whether or not the compiler will use RVO for a given method (assuming the caller doesn't need to modify the result, of course)? How cache-aware do compilers tend to be? For example, is it worth looking into reordering nested loops? Given the scientific nature of the program, floating-point numbers are used everywhere. A significant bottleneck in my code used to be conversions from floating point to integers: the compiler would emit code to save the current rounding mode, change it, perform the conversion, then restore the old rounding mode --- even though nothing in the program ever changed the rounding mode! Disabling this behavior significantly sped up my code. Are there any similar floating-point-related gotchas I should be aware of? One consequence of C++ being compiled and linked separately is that the compiler is unable to do what would seem to be very simple optimizations, such as move method calls like strlen() out of the termination conditions of loop. Are there any optimization like this one that I should look out for because they can't be done by the compiler and must be done by hand? On the flip side, are there any techniques I should avoid because they are likely to interfere with the compiler's ability to automatically optimize code? Lastly, to nip certain kinds of answers in the bud: I understand that optimization has a cost in terms of complexity, reliability, and maintainability. For this particular application, increased performance is worth these costs. I understand that the best optimizations are often to improve the high-level algorithms, and this has already been done.

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