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  • why is this legal, c++ typedef func

    - by acidzombie24
    i did this in msvc 2005. typedef void (*cleanup_t)(); void func(cleanup_t clean) { cleanup_t(); } Why does this compile? and not give me a warning? ok, it gave me a unreferenced formal parameter warning but originally i did this when clean was in a class no there was no unreferenced formal parameter when this code gave me problems. What is cleanup_t(); really doing and what is the point? now for laughs i tried int() and that worked also.

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  • Subtype polymorphism and arrays

    - by user133466
    Computer[] labComputers = new Computer[10]; with public class Computer { ... void toString(){ // print computer specs } } public class Notebook extends Computer{ ... void toString(){ // print computer specs + laptop color } } each subscripted variable labComputers[i] can reference either a Computer object or a Notebook object because Notebook is a subclass of Computer. For the method call labComputers[i].toString(), polymorphism ensures that the correct toString method is called. I wonder what if we do Notebook[] labComputers = new Notebook[10]; what kind or error would I get if I reference with Computer object and a Notebook object

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  • jUnit same exception in different cases

    - by coubeatczech
    Hi, I'm writing a jUnit test for a constructor that parses a String and then check numerous things. When there's wrong data, for every thing, some IllegalArgumentException with different message is thrown. So I would like to write tests for it, but how can i recognize what error was thrown? This is how can I do it: @Test(expected=IllegalArgumentException.class) public void testRodneCisloRok(){ new RodneCislo("891415",dopocitej("891415")); } and this is how I would like to be, but I don't know if it is possible to write it somehow: @Test(expected=IllegalArgumentException.class("error1")) public void testRodneCisloRok(){ new RodneCislo("891415",dopocitej("891415")); }

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  • doubt in - Function Objects - c++

    - by Eternal Learner
    I have a class class fobj{ public: fobj(int i):id(i) {} void operator()() { std::cout<<"Prints"<<std::endl; } private: int id; }; template<typename T> void func(T type) { type(); } My Doubt is if I invoke func like Method 1: func(fobj(1); the message I wanted to print is printed. I was always thinking I needed to do something like Method 2: fobj Iobj(1); // create an instance of the fobj class func(Iobj); //call func by passing Iobj(which is a function object) How does Method 1 work? I mean what exactly happens? and how is a call made to the operator() in class fobj ?

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  • Why Timer does not work if we do not generate a window?

    - by Roman
    Here is the code: import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import javax.swing.JFrame; import javax.swing.Timer; public class TimerSample { public static void main(String args[]) { new JFrame().setVisible(true); ActionListener actionListener = new ActionListener() { public void actionPerformed(ActionEvent actionEvent) { System.out.println("Hello World Timer"); } }; Timer timer = new Timer(500, actionListener); timer.start(); } } It generates a window and then periodically prints "Hello World Timer" in the terminal (Command Prompt). If I comment this line new JFrame().setVisible(true); the application do not print anything to the command line. Why?

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  • asp.net C# variable as Image1.ImageUrl property

    - by ModS
    I would like to Click "buttonImage1" and have that store "photos/Image1.jpg" into a var called Photo. then have ButtonImage2.ImageUrl = (Photo). I am using an UpdatePanel to refresh the area with the images so the only problem is actually setting the variable correctly and then using it correctly. Reworded: how can I store a path to an image in a variable then set it correctly as a image's URL path? protected void Button2_Click(object sender, ImageClickEventArgs e) { Evt = ("~/events/ev2.jpg"); } protected void Image2_Click(object sender, ImageClickEventArgs e) { Image1.ImageUrl = (Evt); }

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  • C++ Static Array Initialization - Memory Issue

    - by donalmg
    Hi, I have a header file which contains a member variable declaration of a static char array: class ABC { public: static char newArray[4]; // other variables / functions private: void setArray(int i, char * ptr); } In the CPP file, I have the array initialized to NULL: char ABC::newArray[4] = {0}; In the ABC constructor, I need to overwrite this value with a value constructed at runtime, such as the encoding of an integer: ABC::ABC() { int i; //some int value defined at runtime memset(newArray, 0, 4); // not sure if this is necessary setArray(i,newArray); } ... void setArray(int i, char * value) { // encoding i to set value[0] ... value [3] } When I return from this function, and print the modified newArray value, it prints out many more characters than the 4 specified in the array declaration. Any ideas why this is the case. I just want to set the char array to 4 characters and nothing further. Thanks...

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  • Help moving multiple images at once with touches

    - by daveMac
    Here is my problem: I am trying to move a puzzle piece around the screen and then connect to the other piece if they are in close proximity. I have achieved this, though it is perhaps a little odd the way I did. My problem though is that once they have connected, I can't figure out how to move them as one image, instead of two separate entities. I would really appreciate any help or suggestions. Here is a sample of what I have been doing: (void)touchesMovedNSSet *)touches withEventUIEvent *)event{ UITouch *touch = [touches anyObject]; [self dispatchTouchEvent:[touch view] toPosition:[touch locationInView:self.view]]; } -(void)dispatchTouchEventUIView *)theView toPositionCGPoint)position{ if ((CGRectContainsPoint([picture frame], position))) { picture.center = position; } if (CGRectContainsPoint([picture2 frame], position)) { picture2.center = position; } }

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  • excplicitly casting constness in

    - by jimifiki
    With the following code void TestF(const double ** testv){;} void callTest(){ double** test; TestF(test); } I get this: error C2664: 'TestF' : cannot convert parameter 1 from 'double **' to 'const double **' I cannot understand why. Why test cannot be silently casted to const double**? Why should I do it explicitly? I know that TestF(const_cast<const double**>(test)) makes my code correct, but I feel this should be unnecessary. Are there some key concepts about const that I'm missing?

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  • How to set a value from another class

    - by Ram
    Its said that property should not be "Set" only and it should be "Get" as well. What should i do if I need to set value to a variable from some other class? The will keep changing so I cannot pass it through constructor. Shall I create a function for this as shown below? class A { public void SetValue() { b = new B(); b.SetTest(10); } } class B { int test; public void SetTest(int value) { test = value; } } What are the other alternatives?

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  • [GCC, linking] How to link app with static library + why this is not working

    - by user278799
    I have a problem. I wrote example code and I want to build it without the error: main.cpp.text+0x5): undefined reference to `test()' Library test1.c #include <stdlib.h> void test() { puts("Dziala"); } test1.h #ifndef TEST1_H #define TEST1_H extern void test(); #endif makefile all: gcc -c ./src/test1.c -o ./lib/test1.o ar rcs ./lib/libtest1.a ./lib/test1.o Program main.cpp #include <test1.h> int main() { test(); return 0; } makefile all: g++ -static -I../test1/include -L../test1/lib ./src/main.cpp -o ./build/MyApp -ltest1 What am I doing wrong?

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  • Thread won't stop when I want it to? (Java)

    - by Stuart
    I have a thread in my screen recording application that won't cooperate: package recorder; import java.awt.AWTException; import java.awt.Insets; import java.io.IOException; import javax.swing.JFrame; public class RepeatThread extends Thread { boolean stop; public volatile Thread recordingThread; JFrame frame; int count = 0; RepeatThread( JFrame myFrame ) { stop = false; frame = myFrame; } public void run() { while( stop == false ) { int loopDelay = 33; // 33 is approx. 1000/30, or 30 fps long loopStartTime = System.currentTimeMillis(); Insets insets = frame.getInsets(); // Get the shape we're recording try { ScreenRecorder.capture( frame.getX() + insets.left, frame.getY() + insets.top, frame.getWidth() - ( insets.left + insets.right ), frame.getHeight() - ( insets.top + insets.bottom ) ); } catch( AWTException e1 ) { // TODO Auto-generated catch block e1.printStackTrace(); } catch( IOException e1 ) { // TODO Auto-generated catch block e1.printStackTrace(); } // Add another picture long loopEndTime = System.currentTimeMillis(); int loopTime = (int )( loopEndTime - loopStartTime ); if( loopTime < loopDelay ) { try { sleep( loopDelay - loopTime ); // If we have extra time, // sleep } catch( Exception e ) { } // If something interrupts it, I don't give a crap; just // ignore it } } } public void endThread() { stop = true; count = 0; ScreenRecorder.reset(); // Once I get this annoying thread to work, I have to make the pictures // into a video here! } } It's been bugging me for ages. It periodically takes screenshots to the specified area. When you start recording, it hides (decativates) the window. On a Mac, when you give an application focus, any hidden windows will activate. In my class WListener (which I have confirmed to work), I have: public void windowActivated(WindowEvent e) { if(ScreenRecorder.recordingThread != null) { ScreenRecorder.recordingThread.endThread(); } } So what SHOULD happen is, the screenshot-taking thread stops when he clicks on the application. However, I must be brutally screwing something up, because when the thread is running, it won't even let the window reappear. This is my first thread, so I expected a weird problem like this. Do you know what's wrong?

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  • A strange error in java generic.

    - by ???
    This is ok: Class<? extends String> stringClass = "a".getClass(); But this gets error: <T> void f(T obj) { Class<? extends T> objClass = obj.getClass(); } I know I can cast it like: <T> void f(T obj) { @SuppressWarnings("unchecked") Class<? extends T> objClass = (Class<? extends T>) obj.getClass(); } But why the previous error? Will the next release of Java 7 will support such usage?

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  • C++ rvalue temporaries in template

    - by aaa
    hello. Can you please explain me the difference between mechanism of the following: int function(); template<class T> void function2(T&); void main() { function2(function()); // compiler error, instantiated as int & const int& v = function(); function2(v); // okay, instantiated as const int& } is my reasoning correct with respect to instantiation? why is not first instantiated as const T&? Thank you

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  • Two phase Construction in C++

    - by tommieb75
    I have as part of assignment to look into a development kit that uses the "two-phase" construction for C++ classes: // Include Header class someFubar{ public: someFubar(); bool Construction(void); ~someFubar(); private: fooObject _fooObj; } In the source // someFubar.cpp someFubar::someFubar : _fooObj(null){ } bool someFubar::Construction(void){ bool rv = false; this->_fooObj = new fooObject(); if (this->_fooObj != null) rv = true; return rv; } someFubar::~someFubar(){ if (this->_fooObj != null) delete this->_fooObj; } Why would this "two-phase" be used and what benefits are there? Why not just instantiate the object initialization within the actual constructor?

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  • including a string as a parameter to a function in a header file? c++

    - by Nara
    hello everyone, total newbie is here :) i have this header file, zeeheader.h, and i wrote some classes in it, i'm having problems giving a string as a parameter to one of the functions: class DeliTest { public: void DeliCheck(Stack*,string); void ComCheck (unsigned,string); bool EofCheck (unsigned,string); }; as i was implementinng it in the cpp file, i added #include to it, it seemed to be working, for example : as i was writing the "data." i got the "length()" appear by the intellisense, so i thought that it was working, but it wasn't. i got errors like: syntax error : identifier 'string' overloaded member function not found in 'DeliTest' this is one of the fucntions in the cpp file: bool DeliTest::EofCheck(unsigned i, string data) { if (i == data.length()-1) return 1; return 0; } am i supposed to be adding something to the header file??

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  • How to stable_sort without copying?

    - by Mehrdad
    Why does stable_sort need a copy constructor? (swap should suffice, right?) Or rather, how do I stable_sort a range without copying any elements? #include <algorithm> class Person { Person(Person const &); // Disable copying public: Person() : age(0) { } int age; void swap(Person &other) { using std::swap; swap(this->age, other.age); } friend void swap(Person &a, Person &b) { a.swap(b); } bool operator <(Person const &other) const { return this->age < other.age; } }; int main() { static size_t const n = 10; Person people[n]; std::stable_sort(people, people + n); }

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  • Xcode method navigation

    - by Bill
    In Xcode 4, I can press Ctrl-6 to get a list of all the methods in the current file. The problem is, if I have private methods declared at the top of my implementation file, say: @interface Foo () -(void)tap:(id)sender; @end @implementation Foo ... -(void)tap:(id)sender { ... } then starting to type "tap" while the method list is visible will just take me to the declaration, since it comes first in the file, when what I really want is the implementation. Is there any way to exclude these declarations from the method list or do I need to resort to separate Foo.h and Foo+Private.h headers? Thanks!

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  • fetching savedInstanceState values, nullpointerexception

    - by Johan
    @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main2); savedInstanceState.putString("foo", "bar"); } @Override public void onRestoreInstanceState(Bundle savedInstanceState) { super.onRestoreInstanceState(savedInstanceState); String myString = savedInstanceState.getString("foo"); Log.i("debug", "saved data: " + myString); } Im trying to preserve some values in an activity, but i recieve the following error: 06-23 23:09:44.038: E/AndroidRuntime(17584): java.lang.RuntimeException: Unable to start activity ComponentInfo{se.johanberntsson.activitytest/se.johanberntsson.activitytest.TestActivity}: java.lang.NullPointerException What did I miss here? Thanks

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  • this pointer to base class constructor?

    - by Rolle
    I want to implement a derived class that should also implement an interface, that have a function that the base class can call. The following gives a warning as it is not safe to pass a this pointer to the base class constructor: struct IInterface { void FuncToCall() = 0; }; struct Base { Base(IInterface* inter) { m_inter = inter; } void SomeFunc() { inter->FuncToCall(); } IInterface* m_inter; }; struct Derived : Base, IInterface { Derived() : Base(this) {} FuncToCall() {} }; What is the best way around this? I need to supply the interface as an argument to the base constructor, as it is not always the dervied class that is the interface; sometimes it may be a totally different class. I could add a function to the base class, SetInterface(IInterface* inter), but I would like to avoid that.

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  • Java generics: actual class as a generic parameter.

    - by user554916
    What do I write instead of "TheClass" to make this work? Or is there an alternative way to do it (possibly without making WithName and WithAge generic)? class Item { NeigborList<TheClass> neighbors; } class WithName extends Item { // here I want neighbors to be a NeighborList<WithName> String name; void someMethod() { System.out.println(neighbors.nearestTo(this).name); } } class WithAge extends Item { // here I want neighbors to be a NeighborList<WithAge> int age; void someOtherMethod() { System.out.println(neighbors.nearestTo(this).age); } }

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  • I know I'm doing something wrong with RaiseCanExecuteChanged and CanExecute

    - by Cowman
    Well after fiddling with MVVM light to get my button to enable and disable when I want it to... I sort of mashed things together until it worked. However, I just know I'm doing something wrong here. I have RaiseCanExecuteChanged and CanExecute in the same area being called. Surely this is not how it's done? Here's my xaml <Button Margin="10, 25, 10, 25" VerticalAlignment="Center" HorizontalAlignment="Center" Width="50" Height="50" Grid.Column="1" Grid.Row="3" Content="Host"> <i:Interaction.Triggers> <i:EventTrigger EventName="Click"> <mvvmLight:EventToCommand Command="{Binding HostChat}" MustToggleIsEnabled="True" /> </i:EventTrigger> </i:Interaction.Triggers> </Button> And here's my code public override void InitializeViewAndViewModel() { view = UnityContainer.Resolve<LoginPromptView>(); viewModel = UnityContainer.Resolve<LoginPromptViewModel>(); view.DataContext = viewModel; InjectViewIntoRegion(RegionNames.PopUpRegion, view, true); viewModel.HostChat = new DelegateCommand(ExecuteHostChat, CanHostChat); viewModel.PropertyChanged += new System.ComponentModel.PropertyChangedEventHandler(ViewModelPropertyChanged); } void ViewModelPropertyChanged(object sender, System.ComponentModel.PropertyChangedEventArgs e) { if (e.PropertyName == "Name" || e.PropertyName == "Port" || e.PropertyName == "Address") { (viewModel.HostChat as DelegateCommand).RaiseCanExecuteChanged(); (viewModel.HostChat as DelegateCommand).CanExecute(); } } public void ExecuteHostChat() { } public bool CanHostChat() { if (String.IsNullOrEmpty(viewModel.Address) || String.IsNullOrEmpty(viewModel.Port) || String.IsNullOrEmpty(viewModel.Name)) { return false; } else return true; } See how these two are together? Surely that can't be right. I mean... it WORKS for me... but something seems wrong about it. Shouldn't RaiseCanExecuteChanged call CanExecute? It doesn't... and so if I don't have that CanExecute in there, my control never toggles its IsEnabled like I need it to. (viewModel.HostChat as DelegateCommand).RaiseCanExecuteChanged(); (viewModel.HostChat as DelegateCommand).CanExecute();

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  • Passing values between pages in JavaScript

    - by buni
    using System; using System.Collections.Generic; using System.Linq; using System.Web; using System.Web.UI; using System.Web.UI.WebControls; using System.Data.SqlClient; using System.Configuration; using System.Text; using System.Web.Services; using System.IO; namespace T_Smade { public partial class ConferenceManagement : System.Web.UI.Page { volatile int i = 0; protected void Page_Load(object sender, EventArgs e) { GetSessionList(); } public void GetSessionList() { string secondResult = ""; string userName = ""; try { if (HttpContext.Current.User.Identity.IsAuthenticated) { userName = HttpContext.Current.User.Identity.Name; } SqlConnection thisConnection = new SqlConnection(@"data Source=ZOLA-PC;AttachDbFilename=D:\2\5.Devp\my DB\ASPNETDB.MDF;Integrated Security=True"); thisConnection.Open(); SqlCommand secondCommand = thisConnection.CreateCommand(); secondCommand.CommandText = "SELECT myApp_Session.session_id FROM myApp_Session, myApp_Role_in_Session where myApp_Role_in_Session.user_name='" + userName + "' and myApp_Role_in_Session.session_id=myApp_Session.session_id"; SqlDataReader secondReader = secondCommand.ExecuteReader(); while (secondReader.Read()) { secondResult = secondResult + secondReader["session_id"].ToString() + ";"; } secondReader.Close(); SqlCommand thisCommand = thisConnection.CreateCommand(); thisCommand.CommandText = "SELECT * FROM myApp_Session;"; SqlDataReader thisReader = thisCommand.ExecuteReader(); while (thisReader.Read()) { test.Controls.Add(GetLabel(thisReader["session_id"].ToString(), thisReader["session_name"].ToString())); string[] compare = secondResult.Split(';'); foreach (string word in compare) { if (word == thisReader["session_id"].ToString()) { test.Controls.Add(GetButton(thisReader["session_name"].ToString(), "Join Session")); } } } thisReader.Close(); thisConnection.Close(); } catch (SqlException ex) { } } private Button GetButton(string id, string name) { Button b = new Button(); b.Text = name; b.ID = "Button_" + id + i; b.Command += new CommandEventHandler(Button_Click); b.CommandArgument = id; i++; return b; } private Label GetLabel(string id, string name) { Label tb = new Label(); tb.Text = name; tb.ID = id; return tb; } protected void Button_Click(object sender, CommandEventArgs e) { Response.Redirect("EnterSession.aspx?session=" + e.CommandArgument.ToString()); } } I have this code when a user clicks a button www.mypage/EnterSession.aspx?session=session_name in the EnterSession.aspx i have used the code below to track the current URL _gaq.push(['pageTrackerTime._trackEvent', 'Category', 'Action', document.location.href, roundleaveSiteEnd]); Now I would also like to track in the Action parameter the session_name from the previous page.see the code below from the previous page test.Controls.Add(GetButton(thisReader["session_name"].ToString(), "Join Session")); Some idea how to do it? Thanx

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  • Break the limit of threading, segmentation fault

    - by user353573
    use pthread_create to create limited number of threads running concurrently Successfully compile and run However, after adding function pointer array to run the function, Segmentation fault Where is wrong? workserver number: 0 Segmentation fault void* workserver(void arg) { int status; while(true) { printf("workserver number: %d\n", (int)arg); ( job_queue[(int)arg])(); sleep(3); status = pthread_mutex_lock(&data.mutex); if(status != 0) printf("%d lock mutex", status); data.value = 1; status = pthread_cond_signal(&data.cond); if(status != 0) printf("%d signal condition", status); status = pthread_mutex_unlock(&data.mutex); if(status != 0) printf("%d unlock mutex", status); } }

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