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  • How can I tell if an ADODB::_RecordsetPtr has already been created?

    - by scottm
    I am trying to write a class that uses ADO to retrieve SQL records. The intent is for the class to maintain one private recordset an other methods move forward, retrieve fields, etc. This is a basic example of my class: class SqlADO { private: ADODB::_RecordsetPtr m_recordset; public: void Open(); //open the connection void Execute(const char* sql); // creates or replaces current recordset void Next(); //moves recordset cursor forward void Field(const char* fieldName); //retrieves field name from current record of the recordset }; My Questions: In the Execute method, how can I check to see that the recordset instance has been created (or do I need to) so that I can close it first? Do you know of any good ADO COM Interop references?

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  • C++ Constructor With Parameters Won't Initialize, Errors C2059 and C2228

    - by Some Girl
    I'm a C# programmer trying to muddle through C++ to create a Windows Forms Application. I have a Windows Form that makes use of a user-created class. Basically I'm trying to use a constructor that takes parameters, but my form won't let me initialize the object with parameter. Here's the code, hopefully somebody can explain the problem to me because I'm completely baffled... Here's my header file: BankAcct.h public ref class BankAcct { private: int money; public: BankAcct(); BankAcct(int); void Deposit(int); void GetBalance(int&); }; And my definition file: BankAcct.cpp #include "StdAfx.h" #include "BankAcct.h" BankAcct::BankAcct() { money = 0; } BankAcct::BankAcct(int startAmt) { money = startAmt; } void BankAcct::Deposit(int depAmt) { money += depAmt; } void BankAcct::GetBalance(int& balance) { balance = money; } And finally my main form. Won't copy the whole thing, of course, but I'm trying to declare the new bank account object, and start it with a balance of say $50. private: BankAcct myAccount(50); //does not work! WHY?? //private: //BankAcct myAccount; //works then in the form constructor my code is this: public: frmBank(void) { InitializeComponent(); int bal; myAccount.GetBalance(bal); lblBankBalance->Text += Convert::ToString(bal); } I've included the BankAcct.h file at the top of my frmBank.h, what else am I doing wrong here? It works great if I use the default constructor (the one that starts the bank balance at zero). I get the following error messages: error C2059: syntax error: 'constant' and error C2228: left of '.GetBalance' must have class/struct/union Thank you for any and all help on this one!!

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  • Command Not working in separate thread in J2me.

    - by RishiPatel
    I am creating a bluetooth application. I created a simple midlet with a exit command and i create a thread for finding the service and discovering the device. While doing so it displays a animated screen on which i added the parent commandListener for exit command. After successful connection both user is represented with greetings(Current screen calls the parent Display method setCurrent for displaying itself). This screen also have CommandListener set to the parent. Now i want to add few more commands. I Implemented the CommandLIstener Interface in this class, added few commands but the commands are not working. I dont whats wen wrong. I am giving u Code snippets to fully describle my issue : - package name Imports here public class MyMidlet extends MIDlet implements CommandListener { public CommandListener theListener; public Display theDisplay; public Command exitCommand; public MyMidlet() { // Retrieve the display for this MIDlet //Create the initial screen } public void startApp() throws MIDletStateChangeException { } public void pauseApp() { } public void destroyApp(boolean unconditional) { } public void commandAction(Command c, Displayable d) { // Determine if the exit command was selected if (c == exitCommand) { //End application here notifyDestroyed(); } else { //Start the new thread here } } } Now here is the code for the class which is invoked by the above midlet in a separate thread; package here; imports here public class MyService implements Runnable, CommandListener { private MyMidlet parent; private StreamConnection conn; private OutputStream output; private InputStream input; public Command sendCommand; private TextField messageToSend Form form; public BChatService(boolean isServer, BChatMidlet parent) { //some stuff here this.parent = parent; } public void run() { //functino for showing animation here try { input = conn.openInputStream(); output = conn.openOutputStream(); } catch (IOException e) { displayError("IO Error", "An error occurred while opening " + "the input and output streams" + "(IOException: " + e.getMessage() + ")"); try { conn.close(); } catch (Exception ex) { } return; } // Create the Form here when service is discoverd and greets the users Command sendCommand = new Command("Send", Command.ITEM, 2); exitCommand = new Command("Exit", Command.EXIT, 1); form.addCommand(exitCommand); form.addCommand(sendCommand); parent.theDisplay.setCurrent(form); form.setCommandListener(this); public void commandAction(Command c, Displayable d) { if (c == exitCommand) { // End the game parent.destroyApp(true); parent.notifyDestroyed(); } if(c == sendCommand) { form.append("SOme text here"); } } } When i select the Send command, the string doesnt append in form neither exit command works. What can be the possible cause for it?? I need to implement this functionality...Is there any other way to achieve this??

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  • CoreData, transient atribute and EXC_BAD_ACCESS.

    - by Lukasz
    I'm trying to build simple file browser and i'm stuck. I defined classes, build window, add controllers, views.. Everything works but only ONE time. Selecting again Folder in NSTableView or trying to get data from Folder.files causing silent EXC_BAD_ACCESS (code=13, address0x0) from main. Info about files i keep outside of CoreData, in simple class, I don't want to save them: #import <Foundation/Foundation.h> @interface TPDrawersFileInfo : NSObject @property (nonatomic, retain) NSString * filename; @property (nonatomic, retain) NSString * extension; @property (nonatomic, retain) NSDate * creation; @property (nonatomic, retain) NSDate * modified; @property (nonatomic, retain) NSNumber * isFile; @property (nonatomic, retain) NSNumber * size; @property (nonatomic, retain) NSNumber * label; +(TPDrawersFileInfo *) initWithURL: (NSURL *) url; @end @implementation TPDrawersFileInfo +(TPDrawersFileInfo *) initWithURL: (NSURL *) url { TPDrawersFileInfo * new = [[TPDrawersFileInfo alloc] init]; if (new!=nil) { NSFileManager * fileManager = [NSFileManager defaultManager]; NSError * error; NSDictionary * infoDict = [fileManager attributesOfItemAtPath: [url path] error:&error]; id labelValue = nil; [url getResourceValue:&labelValue forKey:NSURLLabelNumberKey error:&error]; new.label = labelValue; new.size = [infoDict objectForKey: @"NSFileSize"]; new.modified = [infoDict objectForKey: @"NSFileModificationDate"]; new.creation = [infoDict objectForKey: @"NSFileCreationDate"]; new.isFile = [NSNumber numberWithBool:[[infoDict objectForKey:@"NSFileType"] isEqualToString:@"NSFileTypeRegular"]]; new.extension = [url pathExtension]; new.filename = [[url lastPathComponent] stringByDeletingPathExtension]; } return new; } Next I have class Folder, which is NSManagesObject subclass // Managed Object class to keep info about folder content @interface Folder : NSManagedObject { NSArray * _files; } @property (nonatomic, retain) NSArray * files; // Array with TPDrawersFileInfo objects @property (nonatomic, retain) NSString * url; // url of folder -(void) reload; //if url changed, load file info again. @end @implementation Folder @synthesize files = _files; @dynamic url; -(void)awakeFromInsert { [self addObserver:self forKeyPath:@"url" options:NSKeyValueObservingOptionNew context:@"url"]; } -(void)awakeFromFetch { [self addObserver:self forKeyPath:@"url" options:NSKeyValueObservingOptionNew context:@"url"]; } -(void)prepareForDeletion { [self removeObserver:self forKeyPath:@"url"]; } -(void) observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context { if (context == @"url") { [self reload]; } } -(void) reload { NSMutableArray * result = [NSMutableArray array]; NSError * error = nil; NSFileManager * fileManager = [NSFileManager defaultManager]; NSString * percented = [self.url stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding]; NSArray * listDir = [fileManager contentsOfDirectoryAtURL: [NSURL URLWithString: percented] includingPropertiesForKeys: [NSArray arrayWithObject: NSURLCreationDateKey ] options:NSDirectoryEnumerationSkipsHiddenFiles error:&error]; if (error!=nil) {NSLog(@"Error <%@> reading <%@> content", error, self.url);} for (id fileURL in listDir) { TPDrawersFileInfo * fi = [TPDrawersFileInfo initWithURL:fileURL]; [result addObject: fi]; } _files = [NSArray arrayWithArray:result]; } @end In app delegate i defined @interface TPAppDelegate : NSObject <NSApplicationDelegate> { IBOutlet NSArrayController * foldersController; Folder * currentFolder; } - (IBAction)chooseDirectory:(id)sender; // choose folder and - (Folder * ) getFolderObjectForPath: path { //gives Folder object if already exist or nil if not ..... } - (IBAction)chooseDirectory:(id)sender { //Opens panel, asking for url NSOpenPanel * panel = [NSOpenPanel openPanel]; [panel setCanChooseDirectories:YES]; [panel setCanChooseFiles:NO]; [panel setMessage:@"Choose folder to show:"]; NSURL * currentDirectory; if ([panel runModal] == NSOKButton) { currentDirectory = [[panel URLs] objectAtIndex:0]; } Folder * folderObject = [self getFolderObjectForPath:[currentDirectory path]]; if (folderObject) { //if exist: currentFolder = folderObject; } else { // create new one Folder * newFolder = [NSEntityDescription insertNewObjectForEntityForName:@"Folder" inManagedObjectContext:self.managedObjectContext]; [newFolder setValue:[currentDirectory path] forKey:@"url"]; [foldersController addObject:newFolder]; currentFolder = newFolder; } [foldersController setSelectedObjects:[NSArray arrayWithObject:currentFolder]]; } Please help ;)

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  • Cannot compute equation, always gives zero

    - by user1738391
    Did i miss something? The variable percentage_ always equals 0. I've checked nTimes and winnings, they give the correct values as what is being input. Even when I test out a simple equation like, percentage_=1+1, percentage_ will give 0. Can someone help? #pragma once #include <iostream> #include <string> #include <cstdlib> #include <iomanip> using namespace std; class GuessMachine { private: int nTimes; int winnings; string nM[6]; public: GuessMachine(); void displayPrizes(); void displayMenu(); int getInput(); void checkNumber(); void checkPrize(); }; void GuessMachine::checkPrize() { MagicNumber mn; int prize_=mn.generateNumber(); float percentage_; percentage_ = float (winnings/nTimes*100); //<--On this line percentage is always 0 no matter what winnings and nTimes are cout<<"Percentage is "<<percentage_<<endl; if(percentage_ >= 50) { cout<<"You have scored "<<percentage_<<"% and won "<<nM[prize_]; } else { cout<<"You have scored "<<percentage_<<"%. You lose!!"; } cin.ignore(); cin.ignore(); }

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  • Functioning Socket read no longer works when called in AsyncTask

    - by bibismcbryde
    I'm making an app that sends a string to a server over a socket and then reads the output after the server has processed that data. It worked perfectly when it was my foreground task, but I have since used AsyncTask to show a process dialog while the socket communication runs in the background, and things start breaking after I read the output from the server and then try to close the socket. private class Progressor extends AsyncTask<String, Void, Void> { ProgressDialog dialog; protected void onPreExecute() { dialog = ProgressDialog.show(ClearTalkInputActivity.this, "Loading..", "Analyzing Text", true, false); } protected Void doInBackground(String... strings) { String language = strings[0].toLowerCase(); String the_text = strings[1]; Socket socket = null; DataOutputStream dos = null; DataInputStream dis = null; try { socket = new Socket(my_ip, port); dos = new DataOutputStream(socket.getOutputStream()); dis = new DataInputStream(socket.getInputStream()); dos.writeUTF(language+"****"+the_text); String in = ""; while (in.indexOf("</content>") < 0) { in += dis.readUTF(); } socket.close(); save_str(OUTPUT_KEY, in); } catch (UnknownHostException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } finally { if (socket != null) { try { socket.close(); } catch (IOException e) { e.printStackTrace(); } } } if (dos != null) { try { dos.close(); } catch (IOException e) { e.printStackTrace(); } } if (dis != null) { try { dis.close(); } catch (IOException e) { e.printStackTrace(); } } return null; } protected void onPostExecute() { if (dialog.isShowing()) dialog.dismiss(); startActivity(new Intent (output_intent)); } }

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  • Is it safe to use a boolean flag to stop a thread from running in C#

    - by Lirik
    My main concern is with the boolean flag... is it safe to use it without any synchronization? I've read in several places that it's atomic. class MyTask { private ManualResetEvent startSignal; private CountDownLatch latch; private bool running; MyTask(CountDownLatch latch) { running = false; this.latch = latch; startSignal = new ManualResetEvent(false); } // A method which runs in a thread public void Run() { startSignal.WaitOne(); while(running) { startSignal.WaitOne(); //... some code } latch.Signal(); } public void Stop() { running = false; startSignal.Set(); } public void Start() { running = true; startSignal.Set(); } public void Pause() { startSignal.Reset(); } public void Resume() { startSignal.Set(); } } Is this a safe way to design a task? Any suggestions, improvements, comments? Note: I wrote my custom CountDownLatch class in case you're wondering where I'm getting it from.

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  • How to run an async task afor every x mins in android?

    - by Shan
    how to run the async task at specific time? (I want to run it every 2 mins) I tried using post delayed but it's not working? tvData.postDelayed(new Runnable(){ @Override public void run() { readWebpage(); }}, 100); In the above code readwebpage is function which calls the async task for me.. Right now below is the method which I am using public void onCreate(Bundle savedInstanceState) { readwebapage(); } public void readWebpage() { DownloadWebPageTask task = new DownloadWebPageTask(); task.execute("http://www.google.com"); } private class DownloadWebPageTask extends AsyncTask<String, Void, String> { @Override protected String doInBackground(String... urls) { String response1 = ""; response1=read(); //read is my another function which does the real work response1=read(); super.onPostExecute(response1); return response1; } protected void onPostExecute(String result) { try { Thread.sleep(100); } catch (InterruptedException e) { // TODO Auto-generated catch block e.printStackTrace(); } TextView tvData = (TextView) findViewById(R.id.TextView01); tvData.setText(result); DownloadWebPageTask task = new DownloadWebPageTask(); task.execute(new String[] { "http://www.google.com" }); } } This is what I my code is and it works perfectly fine but the big problem I drains my battery?

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  • Android - dialer icon gets placed in recently used apps after finish()

    - by Donal Rafferty
    In my application I detect the out going call when a call is dialled from the dialer or contacts. This works fine and I then pop up a dialog saying I have detected the call and then the user presses a button to close the dialog which calls finish() on that activity. It all works fine except that when I then hold the home key to bring up the recently used apps the dialer icon is there. And when it is clicked the dialog is brought back into focus in the foreground when the dialog activity should be dead and gone and not be able to be brought back to the foreground. Here is a picture of what I mean. So two questions arise, why would the dialer icon be getting placed there and why would it be recalling my activity to the foreground? Here is the code for that Activity which has a dialog theme: public class CallDialogActivity extends Activity{ boolean isRecording; AudioManager audio_service; public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.dialog); audio_service = (AudioManager) getSystemService(Context.AUDIO_SERVICE); getWindow().addFlags(WindowManager.LayoutParams.FLAG_BLUR_BEHIND); Bundle b = this.getIntent().getExtras(); String number = b.getString("com.networks.NUMBER"); String name = b.getString("com.networks.NAME"); TextView tv = (TextView) findViewById(R.id.voip) ; tv.setText(name); Intent service = new Intent(CallAudio.CICERO_CALL_SERVICE); startService(service); final Button stop_Call_Button = (Button) findViewById(R.id.widget35); this.setVolumeControlStream(AudioManager.STREAM_VOICE_CALL); stop_Call_Button.setOnClickListener(new View.OnClickListener(){ public void onClick(View v){ Intent service = new Intent(CallAudio._CALL_SERVICE); //this is for Android 1.5 (sets speaker going for a few seconds before shutting down) stopService(service); Intent setIntent = new Intent(Intent.ACTION_MAIN); setIntent.addCategory(Intent.CATEGORY_HOME); setIntent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP); startActivity(setIntent); finish(); isRecording = false; } }); final Button speaker_Button = (Button) findViewById(R.id.widget36); speaker_Button.setOnClickListener(new View.OnClickListener(){ public void onClick(View v){ if(true){ audio_service.setSpeakerphoneOn(false); } else{ audio_service.setSpeakerphoneOn(true); } } }); } @Override protected void onResume() { super.onResume(); } @Override protected void onPause() { super.onPause(); } public void onCofigurationChanged(Configuration newConfig) { super.onConfigurationChanged(newConfig); } } It calls a service that uses AudioRecord to record from the Mic and AudioTrack to play it out the earpiece, nothing in the service to do with the dialler. Has anyone any idea why this might be happening?

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  • Windows opaque UserControl not refreshing any graphical changes made on it

    - by Debajyoti Das
    I have created a Windows UserControl. It actually paints a Grid (i.e. vertical and horizontal lines) using Graphics. User can change each cell height and width, and according to that Grid is refreshed. Overriding the OnPaint event I have created the grid. I used SetStyle(ControlStyles.Opaque, true) to make it transparent. I used this control on a form and from there I change the values of the cell height and width but due to Opaque the new grid is overlapping on the previous one and making it clumsy. How do I resolve this? UserControl Code: public partial class Grid : UserControl { public Grid() { InitializeComponent(); SetStyle(ControlStyles.Opaque, true); } private float _CellWidth = 10, _CellHeight = 10; private Color _GridColor = Color.Black; public float CellWidth { get { return this._CellWidth; } set { this._CellWidth = value; } } public float CellHeight { get { return this._CellHeight; } set { this._CellHeight = value; } } public Color GridColor { get { return this._GridColor; } set { this._GridColor = value; } } protected override void OnPaint(PaintEventArgs e) { base.OnPaint(e); Graphics g; float iHeight = this.Height; float iWidth = this.Width; g = e.Graphics; Pen myPen = new Pen(GridColor); myPen.Width = 1; if (this.CellWidth > 0 && this.CellHeight > 0) { for (float X = 0; X <= iWidth; X += this.CellWidth) { g.DrawLine(myPen, X, 0, X, iHeight); } for (float Y = 0; Y <= iHeight; Y += this.CellHeight) { g.DrawLine(myPen, 0, Y, iWidth, Y); } } } public override void Refresh() { base.ResumeLayout(true); base.Refresh(); ResumeLayout(true); } } Form Code: public partial class Form1 : Form { public Form1() { InitializeComponent(); } private void Form1_Load(object sender, EventArgs e) { } private void btnBrowse_Click(object sender, EventArgs e) { try { if (ofdImage.ShowDialog() == System.Windows.Forms.DialogResult.OK) { pbImage.Image = Image.FromFile(ofdImage.FileName); } } catch (Exception ex) { MessageBox.Show(ex.Message); } } private void btnShowGrid_Click(object sender, EventArgs e) { if (grid1.Visible) { grid1.Visible = false; btnShowGrid.Text = "Show"; } else { grid1.Visible = true; btnShowGrid.Text = "Hide"; } } private void btnGridCellMaximize_Click(object sender, EventArgs e) { grid1.CellHeight += 1; grid1.CellWidth += 1; grid1.Refresh(); } private void btnGridCellMinimize_Click(object sender, EventArgs e) { grid1.CellHeight -= 1; grid1.CellWidth -= 1; grid1.Refresh(); } }

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  • Problem in calling a function from different class using protocols-iphone

    - by Muniraj
    I use cocos2d for my game. In which I play a movie and have a separate overlay view for controls.The touches are detected in the overlay view. Now when the touches are detected the function in the game code has to be invoked. But the function is not detected and there is no error. I dont know what has gone wrong. Someone please help me. The code are as follows The protocol part is @protocol Protocol @required -(void) transition1:(id) sender; @end The function which is to be invoked in the game code is (void) transition1:(id) sender { [[Director sharedDirector] replaceScene: [ [Scene node] addChild: [Layer4 node] z:0] ]; } The code in the overlay view in MovieOverlayViewController.h import "Protocol.h" @interface MovieOverlayViewController : UIViewController { UIImageView *overlay; NSObject <Protocol> *transfer; } @end The code in the overlay view in MovieOverlayViewController.m @implementation MovieOverlayViewController (id)init { if ((self = [super init])) self.view = [[[UIView alloc] initWithFrame:[[UIScreen mainScreen] applicationFrame]] autorelease]; return self; } -(void) viewWillAppear:(BOOL)animated { overlay = [[[UIImageView alloc] initWithImage:[UIImage imageNamed:@"overlay.png"]] autorelease]; [self.view addSubview:overlay]; } (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event { UITouch *touch = [touches anyObject]; CGPoint point = [touch locationInView:self.view]; NSLog(@"pointx: %f pointy:%f", point.x, point.y); if (CGRectContainsPoint(CGRectMake(1, 440, 106, 40), point)) { // the function is called here [transfer transition1: nil]; } else if (CGRectContainsPoint(CGRectMake(107, 440, 106, 40), point)) NSLog(@"tab 2 touched"); } (void)dealloc { [overlay release]; [super dealloc]; } @end

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  • Reusable non generic method for generic methods

    - by Jehof
    I have the following base interface public interface IHandler{ void Handle(IMessage message); } and an generic interface inheriting the base interface public interface IHandler<TMessage> : IHandler where TMessage : IMessage{ void Handle(TMessage message); } My classes can implement the interface IHandler<TMessage> mutiple times. IMessage is an base interface for messages and isn´t relevant here. Currently i´m implementing the interfaces as follows. public class ExampleHandler : IHandler<ExampleMessage>, IHandler<OtherExampleMessag>{ void IHandler.Handle(IMessage message){ ExampleMessage example = message as ExampleMessage; if (example != null) { Handle(example); } else { OtherExampleMessage otherExample = message as OtherExampleMessage; if (otherExample != null) { Handle(otherExample); } } public void Handle(ExampleMessage) { //handle message; } public void Handle(OtherExampleMessage) { //handle message; } } What bothers me is the way i have to implement the Handle(IMessage) method, cause in my opinion its many redundant code, and i have to extend the method each time when i implement a new IHandler<TMessage> interface on my class. What i´m looking for is a more generic way to implement the Handle(IMessage) method (maybe in a base class for Handlers), but i´m currently stuck how to do that.

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  • View isn't scrolling back down after I dismiss the keyboard

    - by fmi
    I have a Tab Bar app. One of the views has a UITextView that is hidden by the keyboard when touched. I've set the view to scroll to account for the keyboard but it the view doesn't always return to it's original position after I dismiss the keyboard. Here is my code: //Scroll the view for keyboard - (void)viewWillAppear:(BOOL)animated { void (^keyBoardWillShow) (NSNotification *)= ^(NSNotification * notif) { NSDictionary* info = [notif userInfo]; NSValue* aValue = [info objectForKey:UIKeyboardFrameEndUserInfoKey]; CGSize keyboardSize = [aValue CGRectValue].size; float bottomPoint = (additionalView.frame.origin.y + additionalView.frame.size.height + 10); scrollAmount = keyboardSize.height - (self.view.frame.size.height - bottomPoint); if (scrollAmount > 0) { moveViewUp =YES; [self scrollTheView:YES]; } else moveViewUp = NO; }; [[NSNotificationCenter defaultCenter] addObserverForName:UIKeyboardWillShowNotification object:self.view.window queue:nil usingBlock:keyBoardWillShow]; void (^keyBoardWillHide) (NSNotification *)= ^(NSNotification * notif) { if (moveViewUp) [self scrollTheView:NO]; }; [[NSNotificationCenter defaultCenter] addObserverForName:UIKeyboardWillHideNotification object:self.view.window queue:nil usingBlock:keyBoardWillHide]; [super viewWillAppear:animated]; } - (void)viewWillDisappear:(BOOL)animated { [[NSNotificationCenter defaultCenter] removeObserver:self name:UIKeyboardWillShowNotification object:nil]; [super viewWillDisappear:animated]; } (void)scrollTheView:(BOOL)movedUp { [UIView beginAnimations:nil context:NULL]; [UIView setAnimationDuration:0.3]; CGRect rect = self.view.frame; if (movedUp){ rect.origin.y -= scrollAmount; } else { rect.origin.y += scrollAmount; } self.view.frame = rect; [UIView commitAnimations]; }

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  • Which way is preferred when doing asynchronous WCF calls?

    - by Mikael Svenson
    When invoking a WCF service asynchronous there seems to be two ways it can be done. 1. public void One() { WcfClient client = new WcfClient(); client.BegindoSearch("input", ResultOne, null); } private void ResultOne(IAsyncResult ar) { WcfClient client = new WcfClient(); string data = client.EnddoSearch(ar); } 2. public void Two() { WcfClient client = new WcfClient(); client.doSearchCompleted += TwoCompleted; client.doSearchAsync("input"); } void TwoCompleted(object sender, doSearchCompletedEventArgs e) { string data = e.Result; } And with the new Task<T> class we have an easy third way by wrapping the synchronous operation in a task. 3. public void Three() { WcfClient client = new WcfClient(); var task = Task<string>.Factory.StartNew(() => client.doSearch("input")); string data = task.Result; } They all give you the ability to execute other code while you wait for the result, but I think Task<T> gives better control on what you execute before or after the result is retrieved. Are there any advantages or disadvantages to using one over the other? Or scenarios where one way of doing it is more preferable?

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  • Difference between var and Class class in object creation

    - by Divine
    Its a silly question, however shocked to see different behaviors. Learning a lot. Lets say I have two classes below Class A { public void Display() { } } Class B : A { public void Display() { } } Class C : B { public void Display() { } } Class Final { static void Main() { var c = new C(); // B c = new C(); //My doubt is, both of the above gives different results. May I know B c = new C() creates object of B or C? What I understood is, it creates object of B. Then why we say "new C()"? I agree with C c = new C(); But I thought, B b = new C(); creates object of B. Where we use this style? Only when utilizing runtime polymorphism? (Overriding methods)? } }

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  • Why doesn't g++ pay attention to __attribute__((pure)) for virtual functions?

    - by jchl
    According to the GCC documentation, __attribute__((pure)) tells the compiler that a function has no side-effects, and so it can be subject to common subexpression elimination. This attribute appears to work for non-virtual functions, but not for virtual functions. For example, consider the following code: extern void f( int ); class C { public: int a1(); int a2() __attribute__((pure)); virtual int b1(); virtual int b2() __attribute__((pure)); }; void test_a1( C *c ) { if( c->a1() ) { f( c->a1() ); } } void test_a2( C *c ) { if( c->a2() ) { f( c->a2() ); } } void test_b1( C *c ) { if( c->b1() ) { f( c->b1() ); } } void test_b2( C *c ) { if( c->b2() ) { f( c->b2() ); } } When compiled with optimization enabled (either -O2 or -Os), test_a2() only calls C::a2() once, but test_b2() calls b2() twice. Is there a reason for this? Is it because, even though the implementation in class C is pure, g++ can't assume that the implementation in every subclass will also be pure? If so, is there a way to tell g++ that this virtual function and every subclass's implementation will be pure?

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  • Memory leak with objective-c on alloc

    - by Grunzig
    When I use Instruments to find memory leaks, a leak is detected on Horaires *jour; jour= [[Horaires alloc] init]; // memory leak reported here by Instruments self.lundi = jour; [jour release]; and I don't know why there is a leak at this point. Does anyone can help me? Here's the code. // HorairesCollection.h #import <Foundation/Foundation.h> #import "Horaires.h" @interface HorairesCollection : NSObject < NSCopying > { Horaires *lundi; } @property (nonatomic, retain) Horaires *lundi; -init; -(void)dealloc; @end // HorairesCollection.m #import "HorairesCollection.h" @implementation HorairesCollection @synthesize lundi; -(id)copyWithZone:(NSZone *)zone{ DefibHoraires *another = [[DefibHoraires alloc] init]; another.lundi = [lundi copyWithZone: zone]; [another autorelease]; return another; } -init{ self = [super init]; Horaires *jour; jour= [[Horaires alloc] init]; // memory leak reported here by Instruments self.lundi = jour; [jour release]; return self; } - (void)dealloc { [lundi release]; [super dealloc]; } @end // Horaires.h #import <Foundation/Foundation.h> @interface Horaires : NSObject <NSCopying>{ BOOL ferme; BOOL h24; NSString *h1; } @property (nonatomic, assign) BOOL ferme; @property (nonatomic, assign) BOOL h24; @property (nonatomic, retain) NSString *h1; -init; -(id)copyWithZone:(NSZone *)zone; -(void)dealloc; @end // Horaires.m #import "Horaires.h" @implementation Horaires -(BOOL) ferme { return ferme; } -(void)setFerme:(BOOL)bFerme{ ferme = bFerme; if (ferme) { self.h1 = @""; self.h24 = NO; } } -(BOOL) h24 { return h24; } -(void)setH24:(BOOL)bH24{ h24 = bH24; if (h24) { self.h1 = @""; self.ferme = NO; } } -(NSString *) h1 { return h1; } -(void)setH1:(NSString *)horaire{ [horaire retain]; [h1 release]; h1 = horaire; if (![h1 isEqualToString:@""]) { self.h24 = NO; self.ferme = NO; } } -(id)copyWithZone:(NSZone *)zone{ Horaires *another = [[Horaires alloc] init]; another.ferme = self.ferme; another.h24 = self.h24; another.h1 = self.h1; [another autorelease]; return another; } -init{ self = [super init]; return self; } -(void)dealloc { [h1 release]; [super dealloc]; } @end

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  • difference in using virtual and not using virtual

    - by numerical25
    In C++, whether you choose to use virtual or not, you can still override the base class function. The following compiles just fine... class Enemy { public: void SelectAnimation(); void RunAI(); void Interact() { cout<<"Hi I am a regular Enemy"; } private: int m_iHitPoints; }; class Boss : public Enemy { public: void Interact() { cout<<"Hi I am a evil Boss"; } }; So my question is what is the difference in using or not using the virtual function. And what is the disadvantage.

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  • How to implement a private virtual function within derived classes?

    - by Dane
    Hi, I know why I want to use private virtual functions, but how exactly can I implement them? For example: class Base{ [...] private: virtual void func() = 0; [...] } class Derived1: puplic Base{ void func() { //short implementation is ok here } } class Derived2: puplic Base{ void func(); //long implementation elsewhere (in cpp file) } [...] void Derived2::func() { //long implementation } The first version is ok but not always possible. Isn't the second version simply name hiding? How do you define the Base::func() of Derived2, if you cannot do it within the class declaration of Dereived2? Thanks

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  • c++ protected pointer member to the same class and access privileges

    - by aajmakin
    Hi, Example code is included at the bottom of the message. I'm puzzled about the protected access specifier in a class. I have define a class node which has a protected string member name string name; and a vector of node pointers vector args; Before I thought that a member function of node could not do args[0]-name but a program that does just this does compile and run. However, now I would like to inherit this class and access the name field in one of the args array pointers from this derived class args[0]-name but this does not compile. When I compile the example code below with the commented sections uncommented, the compiler reports: Compiler output: g++ test.cc -o test test.cc: In member function 'void foo::newnode::print_args2()': test.cc:22: error: 'std::string foo::node::name' is protected test.cc:61: error: within this context Compilation exited abnormally with code 1 at Thu Jun 17 12:40:12 Questions: Why can I access the name field of the node pointers in args in class node, because this is what I would excpect from a similarly defined private field in Java. How can I access those fields from the derived class. Example code: #include <iostream> #include <vector> using namespace std; namespace foo { class node; typedef std::vector<node*> nodes; class node { public: node (string _name); void print_args (); void add_node (node* a); protected: nodes args; string name; }; } foo::node::node (string _name) : args(0) { name = _name; } void foo::node::add_node (node* a) { args.push_back(a); } void foo::node::print_args () { for (int i = 0; i < args.size(); i++) { cout << "node " << i << ": " << args[i]->name << endl; } } // namespace foo // { // class newnode : public node // { // public: // newnode (string _name) : node(_name) {} // void print_args2 (); // protected: // }; // } // void foo::newnode::print_args2 () // { // for (int i = 0; i < args.size(); i++) // { // cout << "node " << i << ": " << args[i]->name << endl; // } // } int main (int argc, char** argv) { foo::node a ("a"); foo::node b ("b"); foo::node c ("c"); a.add_node (&b); a.add_node (&c); a.print_args (); // foo::newnode newa ("newa"); // foo::newnode newb ("newb"); // foo::newnode newc ("newc"); // newa.add_node (&newb); // newa.add_node (&newc); // newa.print_args2 (); return 0; }

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  • problem with threads

    - by Nadeem
    i want to be done for 10 times!!, to scan teh number and print it again!!, how i can do that #include <stdio.h> #include <pthread.h> #include <semaphore.h> sem_t m; int n; void *readnumber(void *arg) { scanf("%d",&n); sem_post(&m); } void *writenumber(void *arg) { //int x =3; //while(x>0) //{ //x = x-1; sem_wait(&m); printf("%d",n); //} } int main(){ pthread_t t1, t2; sem_init(&m, 0, 0); pthread_create(&t2, NULL, writenumber, NULL); pthread_create(&t1, NULL, readnumber, NULL); pthread_join(t2, NULL); pthread_join(t1, NULL); sem_destroy(&m); return 0; }

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  • Trouble calling a method from an external class

    - by Bradley Hobbs
    Here is my employee database program: import java.util.*; import java.io.*; import java.io.File; import java.io.FileReader; import java.util.ArrayList; public class P { //Instance Variables private static String empName; private static String wage; private static double wages; private static double salary; private static double numHours; private static double increase; // static ArrayList<String> ARempName = new ArrayList<String>(); // static ArrayList<Double> ARwages = new ArrayList<Double>(); // static ArrayList<Double> ARsalary = new ArrayList<Double>(); static ArrayList<Employee> emp = new ArrayList<Employee>(); public static void main(String[] args) throws Exception { clearScreen(); printMenu(); question(); exit(); } public static void printArrayList(ArrayList<Employee> emp) { for (int i = 0; i < emp.size(); i++){ System.out.println(emp.get(i)); } } public static void clearScreen() { System.out.println("\u001b[H\u001b[2J"); } private static void exit() { System.exit(0); } private static void printMenu() { System.out.println("\t------------------------------------"); System.out.println("\t|Commands: n - New employee |"); System.out.println("\t| c - Compute paychecks |"); System.out.println("\t| r - Raise wages |"); System.out.println("\t| p - Print records |"); System.out.println("\t| d - Download data |"); System.out.println("\t| u - Upload data |"); System.out.println("\t| q - Quit |"); System.out.println("\t------------------------------------"); System.out.println(""); } public static void question() { System.out.print("Enter command: "); Scanner q = new Scanner(System.in); String input = q.nextLine(); input.replaceAll("\\s","").toLowerCase(); boolean valid = (input.equals("n") || input.equals("c") || input.equals("r") || input.equals("p") || input.equals("d") || input.equals("u") || input.equals("q")); if (!valid){ System.out.println("Command was not recognized; please try again."); printMenu(); question(); } else if (input.equals("n")){ System.out.print("Enter the name of new employee: "); Scanner stdin = new Scanner(System.in); empName = stdin.nextLine(); System.out.print("Hourly (h) or salaried (s): "); Scanner stdin2 = new Scanner(System.in); wage = stdin2.nextLine(); wage.replaceAll("\\s","").toLowerCase(); if (!(wage.equals("h") || wage.equals("s"))){ System.out.println("Input was not h or s; please try again"); } else if (wage.equals("h")){ System.out.print("Enter hourly wage: "); Scanner stdin4 = new Scanner(System.in); wages = stdin4.nextDouble(); Employee emp1 = new HourlyEmployee(empName, wages); emp.add(emp1); printMenu(); question();} else if (wage.equals("s")){ System.out.print("Enter annual salary: "); Scanner stdin5 = new Scanner(System.in); salary = stdin5.nextDouble(); Employee emp1 = new SalariedEmployee(empName, salary); printMenu(); question();}} else if (input.equals("c")){ for (int i = 0; i < emp.size(); i++){ System.out.println("Enter number of hours worked by " + emp.get(i) + ":"); } Scanner stdin = new Scanner(System.in); numHours = stdin.nextInt(); System.out.println("Pay: " + emp1.computePay(numHours)); System.out.print("Enter number of hours worked by " + empName); Scanner stdin2 = new Scanner(System.in); numHours = stdin2.nextInt(); System.out.println("Pay: " + emp1.computePay(numHours)); printMenu(); question();} else if (input.equals("r")){ System.out.print("Enter percentage increase: "); Scanner stdin = new Scanner(System.in); increase = stdin.nextDouble(); System.out.println("\nNew Wages"); System.out.println("---------"); // System.out.println(Employee.toString()); printMenu(); question(); } else if (input.equals("p")){ printArrayList(emp); printMenu(); question(); } else if (input.equals("q")){ exit(); } } } Here is one of the class files: public abstract class Employee { private String name; private double wage; protected Employee(String name, double wage){ this.name = name; this.wage = wage; } public String getName() { return name; } public double getWage() { return wage; } public void setName(String name) { this.name = name; } public void setWage(double wage) { this.wage = wage; } public void percent(double wage, double percent) { wage *= percent; } } And here are the errors: P.java:108: cannot find symbol symbol : variable emp1 location: class P System.out.println("Pay: " + emp1.computePay(numHours)); ^ P.java:112: cannot find symbol symbol : variable emp1 location: class P System.out.println("Pay: " + emp1.computePay(numHours)); ^ 2 errors I'm trying to the get paycheck to print out but i'm having trouble with how to call the method. It should take the user inputed numHours and calculate it then print on the paycheck for each employee. Thanks!

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  • Could someone explain __declspec(naked) please?

    - by Scott
    I'm looking into porting a script engine written for Windows to Linux; it's for Winamp's visualization platform AVS. I'm not sure if it's even possible at the moment. From what I can tell the code is taking the addresses of the C functions nseel_asm_atan and nseel_asm_atan_end and storing them inside a table that it can reference during code execution. I've looked at MS's documentation, but I'm unsure what __declspec(naked) really does. What is prolog and epilog code mentioned in the documentation? Is that related to Windows calling conventions? Is this portable? Know of any Linux-based examples using similar techniques? static double (*__atan)(double) = &atan; __declspec ( naked ) void nseel_asm_atan(void) { FUNC1_ENTER *__nextBlock = __atan(*parm_a); FUNC_LEAVE } __declspec ( naked ) void nseel_asm_atan_end(void) {}

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  • Explain the code: c# locking feature and threads

    - by Mendy
    I used this pattern in a few projects, (this snipped of code is from CodeCampServer), I understand what it does, but I'm really interesting in an explanation about this pattern. Specifically: Why is the double check of _dependenciesRegistered. Why to use lock (Lock){}. Thanks. public class DependencyRegistrarModule : IHttpModule { private static bool _dependenciesRegistered; private static readonly object Lock = new object(); public void Init(HttpApplication context) { context.BeginRequest += context_BeginRequest; } public void Dispose() { } private static void context_BeginRequest(object sender, EventArgs e) { EnsureDependenciesRegistered(); } private static void EnsureDependenciesRegistered() { if (!_dependenciesRegistered) { lock (Lock) { if (!_dependenciesRegistered) { new DependencyRegistrar().ConfigureOnStartup(); _dependenciesRegistered = true; } } } } }

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  • Update NSView in function of events

    - by Forchita
    Hi everyone! I have a main view (subclass of NSView) and as i'm new to cocoa, i'd like to know how to update the view in function of events. I know there are many methods that take events such as -(void)mouseMoved:(NSEvent*)event or - (void)mouseClicked:(NSEvent*)event My algorithm to determine what to do is ready. I want to know where I should update the main view: is it in the -(void)mouseMoved:(NSEvent*)event or in the - (void)drawRect:(NSRect)dirtyRect. And if it is in drawRect, then how should i pass the information to it? Thanks in advance!

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