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  • Properties are making trouble

    - by DhavalR
    In my application I have added a Properties.cs file which contains properties that I am would use through out the application. I am getting NullReferenceException = Object reference not set to an instance of an object. Here is the code for Properties.cs public class Properties { private static string type1; public static string Type1 { get { return type1; } set { type1= value; } } } And when I access this property in one of my form I am getting error. e.g. if (Properties.Type1.Equals(string.Empty) || Properties.Type1.Equals(null)) { //// Do something }

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  • Is extending a singleton class wrong?

    - by Anwar Shaikh
    I am creating a logger for an application. I am using a third party logger library. In which logger is implemented as singleton. I extended that logger class because I want to add some more static functions. In these static functions I internally use the instance (which is single) of Logger(which i inherited). I neither creates instance of MyLogger nor re-implemented the getInstance() method of super class. But I am still getting warnings like destructor of MyLogger can not be created as parent class (Loggger) destructor is not accessible. I want to know, I am I doing something wrong? Inheriting the singleton is wrong or should be avoided??

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  • How to test reliability of my own (small) embedded operating system ?

    - by TridenT
    I've written a small operating system for embedded project running on small to medium target. I added some automated unit test with a high test code coverage (95%), but the scope is only the static part. I got some code metrics as complexity and readability. I'm testing my code with a rule checker with MiSRA support, and of course fixed all warnings. I'm testing the code with a static analyzer and again fixed all warnings. What can I do now to test - and improve - the reliability of my OS ? How about the dynamic part ?

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  • How can I require an attribute on a class definition?

    - by spoulson
    Is there a way to enforce a compile requirement for certain attributes on a class or interface implementation? For example, let's say my application uses a series of static classes that contain const int resource values. I'd like to decorate the class in a Description attribute to describe its contents. In concept, I'd like to apply this attribute requirement to an interface, then each static class would implement it with its required Description. I could write a run-time check or a unit test to check compliance. But really a compile-time check would be best. Is there such a thing?

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  • How do I make a jumping dolphin rotate realistically?

    - by Johnny
    I want to program a dolphin that jumps and rotates like a real dolphin. Jumping is not the problem, but I don't know how to make the rotation. At the moment, my dolphin rotates a little weird. But I want that it rotates like a real dolphin does. How can I improve the rotation? public class Game1 : Microsoft.Xna.Framework.Game { GraphicsDeviceManager graphics; SpriteBatch spriteBatch; Texture2D image, water; float Gravity = 5.0F; float Acceleration = 20.0F; Vector2 Position = new Vector2(1200,720); Vector2 Velocity; float rotation = 0; SpriteEffects flip; Vector2 Speed = new Vector2(0, 0); public Game1() { graphics = new GraphicsDeviceManager(this); Content.RootDirectory = "Content"; graphics.PreferredBackBufferWidth = 1280; graphics.PreferredBackBufferHeight = 720; } protected override void Initialize() { base.Initialize(); } protected override void LoadContent() { spriteBatch = new SpriteBatch(GraphicsDevice); image = Content.Load<Texture2D>("cartoondolphin"); water = Content.Load<Texture2D>("background"); flip = SpriteEffects.None; } protected override void Update(GameTime gameTime) { float VelocityX = 0f; float VelocityY = 0f; float time = (float)gameTime.ElapsedGameTime.TotalSeconds; KeyboardState kbState = Keyboard.GetState(); if(kbState.IsKeyDown(Keys.Left)) { rotation = 0; flip = SpriteEffects.None; VelocityX += -5f; } if(kbState.IsKeyDown(Keys.Right)) { rotation = 0; flip = SpriteEffects.FlipHorizontally; VelocityX += 5f; } // jump if the dolphin is under water if(Position.Y >= 670) { if (kbState.IsKeyDown(Keys.A)) { if (flip == SpriteEffects.None) { rotation += 0.01f; VelocityY += 40f; } else { rotation -= 0.01f; VelocityY += 40f; } } } else { if (flip == SpriteEffects.None) { rotation -= 0.01f; VelocityY += -10f; } else { rotation += 0.01f; VelocityY += -10f; } } float deltaY = 0; float deltaX = 0; deltaY = Gravity * (float)gameTime.ElapsedGameTime.TotalSeconds; deltaX += VelocityX * (float)gameTime.ElapsedGameTime.TotalSeconds * Acceleration; deltaY += -VelocityY * (float)gameTime.ElapsedGameTime.TotalSeconds * Acceleration; Speed = new Vector2(Speed.X + deltaX, Speed.Y + deltaY); Position += Speed * (float)gameTime.ElapsedGameTime.TotalSeconds; Velocity.X = 0; if (Position.Y + image.Height/2 > graphics.PreferredBackBufferHeight) Position.Y = graphics.PreferredBackBufferHeight - image.Height/2; base.Update(gameTime); } protected override void Draw(GameTime gameTime) { GraphicsDevice.Clear(Color.CornflowerBlue); spriteBatch.Begin(); spriteBatch.Draw(water, new Rectangle(0, graphics.PreferredBackBufferHeight -100, graphics.PreferredBackBufferWidth, 100), Color.White); spriteBatch.Draw(image, Position, null, Color.White, rotation, new Vector2(image.Width / 2, image.Height / 2), 1, flip, 1); spriteBatch.End(); base.Draw(gameTime); } } I changed my code a little. But I still have some trouble with the rotation. Here's the entire code. The dolphin looks at the wrong direction if I press the left or right key. For example, it looks down if I press the left key. What is wrong with the rotation? At the beginning, the dolphin looks at the left side, but after I pressed a key it just looks down or up. I deleted the "rotation += 0.01f;" lines in the code. Is that correct? public class Game1 : Microsoft.Xna.Framework.Game { GraphicsDeviceManager graphics; SpriteBatch spriteBatch; Texture2D image, water; float Gravity = 5.0F; float Acceleration = 20.0F; Vector2 Position = new Vector2(1200,720); Vector2 Velocity; float rotation = 0; SpriteEffects flip; Vector2 Speed = new Vector2(0, 0); Vector2 prevPos; public Game1() { graphics = new GraphicsDeviceManager(this); Content.RootDirectory = "Content"; graphics.PreferredBackBufferWidth = 1280; graphics.PreferredBackBufferHeight = 720; } protected override void Initialize() { base.Initialize(); } protected override void LoadContent() { spriteBatch = new SpriteBatch(GraphicsDevice); image = Content.Load<Texture2D>("cartoondolphin"); water = Content.Load<Texture2D>("background"); flip = SpriteEffects.None; } protected override void Update(GameTime gameTime) { float VelocityX = 0f; float VelocityY = 0f; float time = (float)gameTime.ElapsedGameTime.TotalSeconds; KeyboardState kbState = Keyboard.GetState(); if(kbState.IsKeyDown(Keys.Left)) { flip = SpriteEffects.None; VelocityX += -5f; } if(kbState.IsKeyDown(Keys.Right)) { flip = SpriteEffects.FlipHorizontally; VelocityX += 5f; } rotation = (float)Math.Atan2(Position.X - prevPos.X, Position.Y - prevPos.Y); prevPos = Position; // jump if the dolphin is under water if(Position.Y >= 670) { if (kbState.IsKeyDown(Keys.A)) { if (flip == SpriteEffects.None) { VelocityY += 40f; } else { VelocityY += 40f; } } } else { if (flip == SpriteEffects.None) { VelocityY += -10f; } else { VelocityY += -10f; } } float deltaY = 0; float deltaX = 0; deltaY = Gravity * (float)gameTime.ElapsedGameTime.TotalSeconds; deltaX += VelocityX * (float)gameTime.ElapsedGameTime.TotalSeconds * Acceleration; deltaY += -VelocityY * (float)gameTime.ElapsedGameTime.TotalSeconds * Acceleration; Speed = new Vector2(Speed.X + deltaX, Speed.Y + deltaY); Position += Speed * (float)gameTime.ElapsedGameTime.TotalSeconds; Velocity.X = 0; if (Position.Y + image.Height/2 > graphics.PreferredBackBufferHeight) Position.Y = graphics.PreferredBackBufferHeight - image.Height/2; base.Update(gameTime); } protected override void Draw(GameTime gameTime) { GraphicsDevice.Clear(Color.CornflowerBlue); spriteBatch.Begin(); spriteBatch.Draw(water, new Rectangle(0, graphics.PreferredBackBufferHeight -100, graphics.PreferredBackBufferWidth, 100), Color.White); spriteBatch.Draw(image, Position, null, Color.White, rotation, new Vector2(image.Width / 2, image.Height / 2), 1, flip, 1); spriteBatch.End(); base.Draw(gameTime); } }

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  • Designing constructors around type erasure in Java

    - by Internet Friend
    Yesterday, I was designing a Java class which I wanted to be initalized with Lists of various generic types: TheClass(List<String> list) { ... } TheClass(List<OtherType> list) { ... } This will not compile, as the constructors have the same erasure. I just went with factory methods differentiated by their names instead: public static TheClass createWithStrings(List<String> list) public static TheClass createWithOtherTypes(List<OtherType> list) This is less than optimal, as there isn't a single obvious location where all the different options for creating instances are available. I tried to search for better design ideas, but found surprisingly few results. What other patterns exist for designing around this problem?

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  • HTML tables in JTextPane showing weird "form" boxes

    - by Ted
    import java.awt.BorderLayout; import java.awt.EventQueue; import javax.swing.JFrame; import javax.swing.JPanel; import javax.swing.JTextPane; import javax.swing.border.EmptyBorder; import javax.swing.text.Document; import javax.swing.text.html.HTMLEditorKit; import javax.swing.text.html.StyleSheet; public class htmlEditor2 extends JFrame { private JPanel contentPane; public static void main(String[] args) { EventQueue.invokeLater(new Runnable() { public void run() { try { htmlEditor2 frame = new htmlEditor2(); frame.setVisible(true); } catch (Exception e) { e.printStackTrace(); } } }); } public htmlEditor2() { setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); setBounds(100, 100, 450, 300); contentPane = new JPanel(); contentPane.setBorder(new EmptyBorder(5, 5, 5, 5)); contentPane.setLayout(new BorderLayout(0, 0)); setContentPane(contentPane); Foo f = new Foo(); f.setText("<html><body><table border=\"1\" width=\"985\" cellpadding=\"3\" cellspacing=\"0\" style=\"table-layout: fixed; border-collapse: collapse; border-width: 0px; border-color: #010101; \"><colgroup><col width=\"328\"></col> <col width=\"328\"></col> <col width=\"328\"></col> </colgroup><tr><td align=\"left\" valign=\"top\" width=\"321\" style=\"border: solid #010101 1px; \"><div align=\"left\"><font face=\"Arial\"><span style=\"font-size:8pt\">row 1</span></font></div></td><td align=\"left\" valign=\"top\" width=\"321\" style=\"border: solid #010101 1px; \"><div align=\"left\"><font face=\"Arial\"><span style=\"font-size:8pt\">row2</span></font></div></td><td align=\"left\" valign=\"top\" width=\"321\" style=\"border: solid #010101 1px; \"><div align=\"left\"><font face=\"Arial\"><span style=\"font-size:8pt\">row3</span></font></div></td></tr><tr><td align=\"left\" valign=\"top\" width=\"321\" style=\"border: solid #010101 1px; \"><div align=\"left\"><span style=\"font-size: 8pt;\">&nbsp;</span></div></td><td align=\"left\" valign=\"top\" width=\"321\" style=\"border: solid #010101 1px; \"><div align=\"left\"><span style=\"font-size: 8pt;\">&nbsp;</span></div></td><td align=\"left\" valign=\"top\" width=\"321\" style=\"border: solid #010101 1px; \"><div align=\"left\"><span style=\"font-size: 8pt;\">&nbsp;</span></div></td></tr><tr><td align=\"left\" valign=\"top\" width=\"321\" style=\"border: solid #010101 1px; \"><div align=\"left\"><span style=\"font-size: 8pt;\">&nbsp;</span></div></td><td align=\"left\" valign=\"top\" width=\"321\" style=\"border: solid #010101 1px; \"><div align=\"left\"><span style=\"font-size: 8pt;\">&nbsp;</span></div></td><td align=\"left\" valign=\"top\" width=\"321\" style=\"border: solid #010101 1px; \"><div align=\"left\"><span style=\"font-size: 8pt;\">&nbsp;</span></div></td></tr></table><div align=\"left\">&nbsp;&nbsp;</div></body></html>"); contentPane.add(f); } class Foo extends JTextPane { public Foo() { super(); HTMLEditorKit kit = new HTMLEditorKit(); setEditorKit(kit); StyleSheet styleSheet = kit.getStyleSheet(); styleSheet.addRule(""); //in case I need to add a CSS Document doc = kit.createDefaultDocument(); setDocument(doc); } } } I would paste a nicely formatted version of the html, but I'm not sure how to do it on here... So yeah.. I just want to know how to get rid of those weird colgroup and col boxes in my table and how to make the table work normally! Thanks yall!

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  • Embedding Python and adding C functions to the interpreter

    - by monoceres
    I'm currently writing an applications that embedds the python interpreter. The idea is to have the program call user specified scripts on certain events in the program. I managed this part but now I want the scripts to be able to call functions in my program. Here's my code so far: #include "python.h" static PyObject* myTest(PyObject* self,PyObject *args) { return Py_BuildValue("s","123456789"); } static PyMethodDef myMethods[] = {{"myTest",myTest},{NULL,NULL}}; int main() { Py_Initialize(); Py_InitModule("PROGRAM",myMethods); PyRun_SimpleString("print PROGRAM.myTest()"); Py_Finalize(); } Thanks!

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  • Problem in suspending 2 threads at the same time in MFC!

    - by kiddo
    I am learning about threading and multithreading..so i just created a small application in which i will update the progressbar and a static text using threading.I vl get two inputs from the user, start and end values for how long the loop should rotate.I have 2threads in my application. Thread1- to update the progressbar(according to the loop) the static text which will show the count(loop count). Thread2 - to update the another static text which will just diplay a name Basically if the user clicks start, the progressbar steps up and at the same time filecount and the name are displayed parallely. There's is another operation where if the user clicks pause it(thread) has to suspend until the user clicks resume. The problem is,the above will not work(will not suspend and resume) for both thread..but works for a singlw thread. Please check the code to get an idea and reply me what can done! on button click start void CThreadingEx3Dlg::OnBnClickedStart() { m_ProgressBar.SetRange(start,end); myThread1 = AfxBeginThread((AFX_THREADPROC)MyThreadFunction1,this); myThread2 = AfxBeginThread((AFX_THREADPROC)MyThreadFunction2,this); } thread1 UINT MyThreadFunction1(LPARAM lparam) { CThreadingEx3Dlg* pthis = (CThreadingEx3Dlg*)lparam; for(int intvalue =pthis->start;intvalue<=pthis->end; ++intvalue) { pthis->SendMessage(WM_MY_THREAD_MESSAGE1,intvalue); } return 0; } thread1 function LRESULT CThreadingEx3Dlg::OnThreadMessage1(WPARAM wparam,LPARAM lparam) { int nProgress= (int)wparam; m_ProgressBar.SetPos(nProgress); CString strStatus; strStatus.Format(L"Thread1:Processing item: %d", nProgress); m_Static.SetWindowText(strStatus); Sleep(100); return 0; } thread2 UINT MyThreadFunction2(LPARAM lparam) { CThreadingEx3Dlg* pthis = (CThreadingEx3Dlg*)lparam; for(int i =pthis->start;i<=pthis->end;i++) { pthis->SendMessage(WM_MY_THREAD_MESSAGE2,i); } return 0; } thread2 function LRESULT CThreadingEx3Dlg::OnThreadMessage2(WPARAM wparam,LPARAM lparam) { m_Static1.GetDlgItem(IDC_STATIC6); m_Static1.SetWindowTextW(L"Thread2 Running"); Sleep(100); m_Static1.SetWindowTextW(L""); Sleep(100); return TRUE; } void CThreadingEx3Dlg::OnBnClickedPause() { // TODO: Add your control notification handler code here if(!m_Track) { m_Track = TRUE; GetDlgItem(IDCANCEL)->SetWindowTextW(L"Resume"); myThread1->SuspendThread(); WaitForSingleObject(myThread1->m_hThread,INFINITE); myThread2->SuspendThread(); m_Static.SetWindowTextW(L"Paused.."); } else { m_Track = FALSE; GetDlgItem(IDCANCEL)->SetWindowTextW(L"Pause"); myThread1->ResumeThread(); myThread2->ResumeThread(); /*myEventHandler.SetEvent(); WaitForSingleObject(myThread1->m_hThread,INFINITE);*/ } }

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  • Is this a correct implementation of singleton C++?

    - by Kamal
    class A{ static boost::shared_ptr<A> getInstance(){ if(pA==NULL){ pA = new A(); } return boost::shared_ptr(pA); } //destructor ~A(){ delete pA; pA=NULL; } private: A(){ //some initialization code } //private assigment and copy constructors A(A const& copy); // Not Implemented A& operator=(A const& copy); // Not Implemented static A* pA; }; A* A::pA = NULL;

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  • Queue access to the database to avoid multiple cache items

    - by MikeJ
    I have a music related ASP.NET web site which caches a lot of static information from the database on the first request. Sometimes, the application is reset and cache is cleared while the application is on heavy load and then all http requests go to the database to retrieve that static data and cache it for other requests. How can I ensure that only one request go to the database and cache the results, so that other request simply read that info from cache and not needlessly retrieve the same info over and over again. Can I use thread locking? For example, can I do something like lock(this) { db access here }?

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  • Java RMI cannot connect to host from external client.

    - by Koe
    I've been using RMI in this project for a while. I've gotten the client program to connect (amongst other things) to the server when running it over my LAN, however when running it over the internet I'm running into the following exception: java.rmi.ConnectException: Connection refused to host: (private IP of host machine); nested exception is: java.net.ConnectException: Connection timed out: connect at sun.rmi.transport.tcp.TCPEndpoint.newSocket(Unknown Source) at sun.rmi.transport.tcp.TCPChannel.createConnection(Unknown Source) at sun.rmi.transport.tcp.TCPChannel.newConnection(Unknown Source) at sun.rmi.server.UnicastRef.invoke(Unknown Source) at java.rmi.server.RemoteObjectInvocationHandler.invokeRemoteMethod(Unknown Source) at java.rmi.server.RemoteObjectInvocationHandler.invoke(Unknown Source) at $Proxy1.ping(Unknown Source) at client.Launcher$PingLabel.runPing(Launcher.java:366) at client.Launcher$PingLabel.<init>(Launcher.java:353) at client.Launcher.setupContentPane(Launcher.java:112) at client.Launcher.<init>(Launcher.java:99) at client.Launcher.main(Launcher.java:59) Caused by: java.net.ConnectException: Connection timed out: connect at java.net.PlainSocketImpl.socketConnect(Native Method) at java.net.PlainSocketImpl.doConnect(Unknown Source) at java.net.PlainSocketImpl.connectToAddress(Unknown Source) at java.net.PlainSocketImpl.connect(Unknown Source) at java.net.SocksSocketImpl.connect(Unknown Source) at java.net.Socket.connect(Unknown Source) at java.net.Socket.connect(Unknown Source) at java.net.Socket.<init>(Unknown Source) at java.net.Socket.<init>(Unknown Source) at sun.rmi.transport.proxy.RMIDirectSocketFactory.createSocket(Unknown Source) at sun.rmi.transport.proxy.RMIMasterSocketFactory.createSocket(Unknown Source) ... 12 more This error is remeniscent of my early implementation of RMI and I can obtain the error verbatum if I run the client locally without the server program running as well. To me Connection Timed Out means a problem with the server's response. Here's the client initiation: public static void main(String[] args) { try { String host = "<WAN IP>"; Registry registry = LocateRegistry.getRegistry(host, 1099); Login lstub = (Login) registry.lookup("Login Server"); Information istub = (Information) registry.lookup("Game Server"); new Launcher(istub, lstub); } catch (RemoteException e) { System.err.println("Client exception: " + e.toString()); e.printStackTrace(); } catch (NotBoundException e) { System.err.println("Client exception: " + e.toString()); e.printStackTrace(); } } Interestingly enough no Remote Exception is thrown here. Here's the server initiation: public static void main(String args[]) { try { GameServer gobj = new GameServer(); Information gstub = (Information) UnicastRemoteObject.exportObject( gobj, 1099); Registry registry = LocateRegistry.createRegistry(1099); registry.bind("Game Server", gstub); LoginServer lobj = new LoginServer(gobj); Login lstub = (Login) UnicastRemoteObject.exportObject(lobj, 7099); // Bind the remote object's stub in the registry registry.bind("Login Server", lstub); System.out.println("Server ready"); } catch (Exception e) { System.err.println("Server exception: " + e.toString()); e.printStackTrace(); } } Bad practice with the catch(Exception e) I know but bear with me. Up to this stage I know it works fine over the LAN, here's where the exception occurs over the WAN and is the first place a method in the server is called: private class PingLabel extends JLabel { private static final long serialVersionUID = 1L; public PingLabel() { super(""); runPing(); } public void setText(String text) { super.setText("Ping: " + text + "ms"); } public void runPing() { try { PingThread pt = new PingThread(); gameServer.ping(); pt.setRecieved(true); setText("" + pt.getTime()); } catch (RemoteException e) { e.printStackTrace(); } } } That's a label placed on the launcher as a ping test. the method ping(), in gameserver does nothing, as in is a null method. It's worth noting also that ports 1099 and 7099 are forwarded to the server machine (which should be obvious from the stack trace). Can anyone see anyting I'm missing/doing wrong? If you need any more information just ask. EDIT: I'm practically certain the problem has nothing to do with my router settings. When disabling my port forwarding settings I get a slightly different error: Client exception: java.rmi.ConnectException: Connection refused to host: (-WAN IP NOT LOCAL IP-); but it appears both on the machine locally connected to the server and on the remote machine. In addition, I got it to work seamlessly when connecting the server straight tho the modem (cutting out the router. I can only conclude the problem is in my router's settings but can't see where (I've checked and double checked the port forwarding page). That's the only answer i can come up with.

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  • .NET SerialPort.Read skipps bytes

    - by Lukas Rieger
    Solution Reading the data byte wise via "port.ReadByte" is too slow, the problem is inside the SerialPort class. i changed it to reading bigger chunks via "port.Read" and there are now no buffer overruns. although i found the solution myself, writing it down helped me and maybe someone else has the same problem and finds this via google... (how can i mark it as answered?) EDIT 2 by setting port.ReadBufferSize = 2000000; i can delay the problem for ~30 seconds. so it seems, .Net really is too slow... since my application is not that critical, i just set the buffer to 20MB, but i am still interested in the cause. EDIT i just tested something i had not thought of before (shame on me): port.ErrorReceived += (object self, SerialErrorReceivedEventArgs se_arg) => { Console.Write("| Error: {0} | ", System.Enum.GetName(se_arg.EventType.GetType(), se_arg.EventType)); }; and it seems that i have an overrun. Is the .Net implementation too slow for 500k or is there an error on my side? Original Question i built a very primitive oszilloscope (avr, which sends adc data over uart to an ftdi chip). On the pc side i have a WPF Programm that displays this data. The Protokoll is: two sync bytes (0xaffe) - 14 data bytes - two sync bytes - 14 data bytes - ... i use 16bit values, so inside the 14 data bytes are 7 channels (lsb first). I verified the uC Firmware with hTerm, and it does send and receive everything correct. But, if i try to read the data with C#, sometimes some bytes are lost. The oszilloscop programm is a mess, but i created a small sample application, which has the same symptoms. I added two extension methods to a) read one byte from the COM Port and ignore -1 (EOF) and b) wait for the sync pattern. The sample programm first syncs onto the data stream by waiting for (0xaffe) and then compares the received bytes with the expected values. the loop runs a few times until an assert failed message pops up. I could not find anything about lost bytes via google, any help would be appreciated. Code using System; using System.Collections.Generic; using System.Diagnostics; using System.IO.Ports; using System.Linq; using System.Text; using System.Threading.Tasks; namespace SerialTest { public static class SerialPortExtensions { public static byte ReadByteSerial(this SerialPort port) { int i = 0; do { i = port.ReadByte(); } while (i < 0 || i > 0xff); return (byte)i; } public static void WaitForPattern_Ushort(this SerialPort port, ushort pattern) { byte hi = 0; byte lo = 0; do { lo = hi; hi = port.ReadByteSerial(); } while (!(hi == (pattern >> 8) && lo == (pattern & 0x00ff))); } } class Program { static void Main(string[] args) { //500000 8n1 SerialPort port = new SerialPort("COM3", 500000, Parity.None, 8, StopBits.One); port.Open(); port.DiscardInBuffer(); port.DiscardOutBuffer(); //Sync port.WaitForPattern_Ushort(0xaffe); byte hi = 0; byte lo = 0; int val; int n = 0; // Start Loop, the stream is already synced while (true) { //Read 7 16-bit values (=14 Bytes) for (int i = 0; i < 7; i++) { lo = port.ReadByteSerial(); hi = port.ReadByteSerial(); val = ((hi << 8) | lo); Debug.Assert(val != 0xaffe); } //Read two sync bytes lo = port.ReadByteSerial(); hi = port.ReadByteSerial(); val = ((hi << 8) | lo); Debug.Assert(val == 0xaffe); n++; } } } }

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  • How would you write this C# code succinctly in Ruby?

    - by Valentin Vasilyev
    Here is the code: using System; using System.Collections.Generic; using System.Linq; namespace cs2 { class Program { static void Main(string[] args) { var i=Fibs().TakeWhile(x=>x < 1000).Where(x=>x % 2==0).Sum(); } static IEnumerable<long> Fibs() { long a = 0, b = 1; while (true) { yield return b; b += a; a = b - a; } } } } If it is possible, please give an example.

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  • My own HtmlHelper don't work in Asp.Net MVC 2

    - by name1ess0ne
    I have HtmlHelper in ASP.NET MVC 1. Now I wont to migrate to ASP.NET MVC 2, but this helper don't work =( public static string Image(this HtmlHelper helper, string url, string alt) { return string.Format("<img src=\"{0}\" alt=\"{1}\" />", url, alt); } public static string ImageLink<T>(this HtmlHelper helper, Expression<Action<T>> linkUrlAction, string imageUrlPath, string altText) where T : Controller { string linkUrl = helper.BuildUrlFromExpression(linkUrlAction);//compile time error string img = helper.Image(imageUrlPath, altText); string outputUrl = string.Format(@"<a href='{0}'>{1}</a>", linkUrl, img); return outputUrl; } Error: 'System.Web.Mvc.HtmlHelper' does not contain a definition for 'BuildUrlFromExpression' How I can fix this error?

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  • C# Fake Enum TypeInitializationException

    - by userk
    I'm trying to create a class that works as a flexible enum. I came with this idea, with 2 additional static methods that allow me to add new members to that list and get only members from that list. public class LikeEnum { private static List<LikeEnum> list = new List<LikeEnum>() { new LikeEnum("One"), new LikeEnum("Two") }; private string value; private LikeEnum(string value) { this.value = value; } } Unfortunately the List list is only initialized as null so this doesn't work... Any ideas or suggestions?

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  • help me with xor encryption in c#

    - by x86shadow
    I wrote this code in c# to encrypt a text with a key : using System; using System.Linq; using System.Collections.Generic; using System.Text; namespace ENCRYPT { class XORENC { private static int Bin2Dec(string num) { int _num = 0; for (int i = 0; i < num.Length; i++) { _num += (int)Math.Pow(2, num.Length - i - 1) * int.Parse(num[i].ToString()); } return _num; } private static string Dec2Bin(int num) { if (num < 2) return num.ToString(); return Dec2Bin(num / 2) + (num % 2).ToString(); } public static string StrXor(string str, string key) { string _str = ""; string _key = ""; string _dec = ""; string _temp = ""; for (int i = 0; i < str.Length; i++) { _temp = Dec2Bin(str[i]); for (int j = 0; j < 8 - _temp.Length + 1; j++) { _temp = '0' + _temp; } _str += _temp; } for (int i = 0; i < key.Length; i++) { _temp = Dec2Bin(key[i]); for (int j = 0; j < 8 - _temp.Length + 1; j++) { _temp = '0' + _temp; } _key += _temp; } while (_key.Length < _str.Length) { _key += _key; } if (_key.Length > _str.Length) _key = _key.Substring(0, _str.Length); for (int i = 0; i < _str.Length; i++) { if (_str[i] == _key[i]) { _dec += '0'; } else { _dec += '1'; } } _str = ""; for (int i = 0; i < _dec.Length; i = i + 8) { char _chr = (char)0; _chr = (char)Bin2Dec(_dec.Substring(i, 8)); _str += _chr; } return _str; } } } the problem is that I always get error when I want to decrypt an encryted text with this code. see the example below for more info : string enc_text = ENCRYPT.XORENC("abc","a"); //enc_text = " ??" string dec_text = ENCRYPT.XORENC(enc_text,"a"); //ERROR any one can help ?

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  • Statement.RETURN_GENERATED_KEYS concept

    - by rits
    import java.sql.* ; import java.util.* ; import java.io.* ; class DataBaseFactory{ public static Connection getConnection(){ ... ... ... ... } } class Demo{ public static void main(String []args) throws SQLException{ Connection con = DataBaseFactory.getConnection() ; //This is throwing exception //PreparedStatement ps = con.prepareStatement("insert into user values(?,?)", Statement.RETURN_GENERATED_KEYS) ; //But this is working fine PreparedStatement ps = con.prepareStatement("insert into user values(?,?)") ; } } thnx in advance to all the java people here....

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  • Qt C++ signals and slots did not fire

    - by Xegara
    I have programmed Qt a couple of times already and I really like the signals and slots feature. But now, I guess I'm having a problem when a signal is emitted from one thread, the corresponding slot from another thread is not fired. The connection was made in the main program. This is also my first time to use Qt for ROS which uses CMake. The signal fired by the QThread triggered their corresponding slots but the emitted signal of my class UserInput did not trigger the slot in tflistener where it supposed to. I have tried everything I can. Any help? The code is provided below. Main.cpp #include <QCoreApplication> #include <QThread> #include "userinput.h" #include "tfcompleter.h" int main(int argc, char** argv) { QCoreApplication app(argc, argv); QThread *thread1 = new QThread(); QThread *thread2 = new QThread(); UserInput *input1 = new UserInput(); TfCompleter *completer = new TfCompleter(); QObject::connect(input1, SIGNAL(togglePause2()), completer, SLOT(toggle())); QObject::connect(thread1, SIGNAL(started()), completer, SLOT(startCounting())); QObject::connect(thread2, SIGNAL(started()), input1, SLOT(start())); completer->moveToThread(thread1); input1->moveToThread(thread2); thread1->start(); thread2->start(); app.exec(); return 0; } What I want to do is.. There are two seperate threads. One thread is for the user input. When the user enters [space], the thread emits a signal to toggle the boolean member field of the other thread. The other thread 's task is to just continue its process if the user wants it to run, otherwise, the user does not want it to run. I wanted to grant the user to toggle the processing anytime that he wants, that's why I decided to bring them into seperate threads. The following codes are the tflistener and userinput. tfcompleter.h #ifndef TFCOMPLETER_H #define TFCOMPLETER_H #include <QObject> #include <QtCore> class TfCompleter : public QObject { Q_OBJECT private: bool isCount; public Q_SLOTS: void toggle(); void startCounting(); }; #endif tflistener.cpp #include "tfcompleter.h" #include <iostream> void TfCompleter::startCounting() { static uint i = 0; while(true) { if(isCount) std::cout << i++ << std::endl; } } void TfCompleter::toggle() { // isCount = ~isCount; std::cout << "isCount " << std::endl; } UserInput.h #ifndef USERINPUT_H #define USERINPUT_H #include <QObject> #include <QtCore> class UserInput : public QObject { Q_OBJECT public Q_SLOTS: void start(); // Waits for the keypress from the user and emits the corresponding signal. public: Q_SIGNALS: void togglePause2(); }; #endif UserInput.cpp #include "userinput.h" #include <iostream> #include <cstdio> // Implementation of getch #include <termios.h> #include <unistd.h> /* reads from keypress, doesn't echo */ int getch(void) { struct termios oldattr, newattr; int ch; tcgetattr( STDIN_FILENO, &oldattr ); newattr = oldattr; newattr.c_lflag &= ~( ICANON | ECHO ); tcsetattr( STDIN_FILENO, TCSANOW, &newattr ); ch = getchar(); tcsetattr( STDIN_FILENO, TCSANOW, &oldattr ); return ch; } void UserInput::start() { char c = 0; while (true) { c = getch(); if (c == ' ') { Q_EMIT togglePause2(); std::cout << "SPACE" << std::endl; } c = 0; } } Here is the CMakeLists.txt. I just placed it here also since I don't know maybe the CMake has also a factor here. CMakeLists.txt ############################################################################## # CMake ############################################################################## cmake_minimum_required(VERSION 2.4.6) ############################################################################## # Ros Initialisation ############################################################################## include($ENV{ROS_ROOT}/core/rosbuild/rosbuild.cmake) rosbuild_init() set(CMAKE_AUTOMOC ON) #set the default path for built executables to the "bin" directory set(EXECUTABLE_OUTPUT_PATH ${PROJECT_SOURCE_DIR}/bin) #set the default path for built libraries to the "lib" directory set(LIBRARY_OUTPUT_PATH ${PROJECT_SOURCE_DIR}/lib) # Set the build type. Options are: # Coverage : w/ debug symbols, w/o optimization, w/ code-coverage # Debug : w/ debug symbols, w/o optimization # Release : w/o debug symbols, w/ optimization # RelWithDebInfo : w/ debug symbols, w/ optimization # MinSizeRel : w/o debug symbols, w/ optimization, stripped binaries #set(ROS_BUILD_TYPE Debug) ############################################################################## # Qt Environment ############################################################################## # Could use this, but qt-ros would need an updated deb, instead we'll move to catkin # rosbuild_include(qt_build qt-ros) rosbuild_find_ros_package(qt_build) include(${qt_build_PACKAGE_PATH}/qt-ros.cmake) rosbuild_prepare_qt4(QtCore) # Add the appropriate components to the component list here ADD_DEFINITIONS(-DQT_NO_KEYWORDS) ############################################################################## # Sections ############################################################################## #file(GLOB QT_FORMS RELATIVE ${CMAKE_CURRENT_SOURCE_DIR} ui/*.ui) #file(GLOB QT_RESOURCES RELATIVE ${CMAKE_CURRENT_SOURCE_DIR} resources/*.qrc) file(GLOB_RECURSE QT_MOC RELATIVE ${CMAKE_CURRENT_SOURCE_DIR} FOLLOW_SYMLINKS include/rgbdslam_client/*.hpp) #QT4_ADD_RESOURCES(QT_RESOURCES_CPP ${QT_RESOURCES}) #QT4_WRAP_UI(QT_FORMS_HPP ${QT_FORMS}) QT4_WRAP_CPP(QT_MOC_HPP ${QT_MOC}) ############################################################################## # Sources ############################################################################## file(GLOB_RECURSE QT_SOURCES RELATIVE ${CMAKE_CURRENT_SOURCE_DIR} FOLLOW_SYMLINKS src/*.cpp) ############################################################################## # Binaries ############################################################################## rosbuild_add_executable(rgbdslam_client ${QT_SOURCES} ${QT_MOC_HPP}) #rosbuild_add_executable(rgbdslam_client ${QT_SOURCES} ${QT_RESOURCES_CPP} ${QT_FORMS_HPP} ${QT_MOC_HPP}) target_link_libraries(rgbdslam_client ${QT_LIBRARIES})

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  • Accessing wrapped method attribute in C#

    - by prostynick
    I have following code: public static void ProcessStep(Action action) { //do something here if (Attribute.IsDefined(action.Method, typeof(LogAttribute))) { //do something here [1] } action(); //do something here } For easy use I have some similar methods using method above. For example: public static void ProcessStep(Action<bool> action) { ProcessStep(() => action(true)); //this is only example, don't bother about hardcoded true } But when I use the second method (the one above), even if original action had attribute, code [1] will not be executed. How can I find if method is only wrapper and underlying method contains attribute and how to access this attribute?

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  • Question regarding two dimensional array

    - by Sherwood Hu
    I have some problems using two dimensional array in the code and need some help. static const int PATTERNS[20][4]; static void init_PATTERN() { // problem #1 int (&patterns)[20][4] = const_cast<int[20][4]>(PATTERNS); ... } extern void UsePattern(int a, const int** patterns, int patterns_size); // problem #2 UsePattern(10, PATTERNS, sizeof(PATTERNS)/sizeof(PATTERNS[0])); in the first statement, I need to cast the const off the two dimensional array PATTERNS. The reason for this is that the init function is called only once, and in the remaining code, PATTERNS is strictly read-only. In the second statement, I need to pass PATTERNS array to the int** argument. Direct passing resulted a compile error. Thanks!

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  • jQuery Validation Plugin: Packer undefined error?

    - by Rosarch
    I'm using the jQuery validation plugin from bassistance.de. It works fine. From <head>: <script type="text/javascript" src="/static/JQuery.js"></script> <script type="text/javascript" src="/static/js-lib/jquery.validate.pack.js"></script> <script type="text/javascript" src="/static/js-lib/jquery.validate.additional-methods.js"></script> At first, this was the only validation code I had, and it worked: $("form").validate(); $("#form-username").rules("add", { required: true, email: true, }); It was validating this HTML: <form id="form-username-form" action="api/user_of_email" method="get"> <p> <label for="form-username">Email:</label> <input type="text" name="email" id="form-username" /> <input type="submit" value="Submit" id="form-submit" /> </p> </form> Great, everything works. But then I add this JS: $("#form-choose-options input[type='text']").rules("add", { number: true, }); to validate this markup: <form id="form-choose-options" action="api/set_options" method="get"> <p> <label for="form-min-credits">Min credits per term:</label><input type="text" name="min_credits" id="form-min-credits" /> <br /> <label for="form-optimal-credits">Optimal credits per term:</label><input type="text" name="optimal_credits" id="form-optimal-credits" /> <br /> <label for="form-max-credits">Max credits per term:</label><input type="text" name="max_credits" id="form-max-credits" /> <br /> <label for="form-low-GPA">Lowest acceptable GPA:</label><input type="text" name="low_GPA" id="form-low-GPA" /> <br /> <label for="form-high-GPA">Highest realistic GPA:</label><input type="text" name="high_GPA" id="form-high-GPA" /> <br /> <input type="hidden" class="user-pk" name="pk"/> <input type="submit" value="Submit" /> </p> </form> This causes a javascript error on document load: $.data(f.form, "validator") is undefined The error is from the packer function. What am I doing wrong?

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  • LinkDemand error on webserver when using TrackSource

    - by robertpnl
    Hi, On a webserver (shared hosting provider) I published a website with a ADO.Net Framework model in use with MySql Connector 6.3.1. When I request a page, a Security Exception will be happen with this error messages: "LinkDemand The type of the first permission that failed was: System.Security.Permissions.SecurityPermission The Zone of the assembly that failed was: MyComputer ". This exception raised when code collect the listeners of a tracksource: public class MySqlTrace { private static TraceSource source = new TraceSource("mysql"); static MySqlTrace() { foreach (TraceListener listener in source.Listeners) // <-- Exception throw here { // ... } } } The web.config doesn't have any trace data or system.diagnostics. My question is, why will a get a LinkDemand security exception during collecting the source listeners. What can maybe be wrong in here?

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