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  • static thread function access non-static class member in C++

    - by user397390
    Class Test{ int value; static void* thread_func(void* args){ value++; } void newthread(){ pthread_create(&thread_func,...); } } I'm trying to create a thread in Class Test. Therefore compiler forces me to make thread_func static. However I cannot access the non-static member "value" anymore. It says: invalid use of member 'Class::value' in static member function Is there a way around it?

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  • C++ Dynamic object construction

    - by Rajesh Subramanian
    I have a base class, class Msg { ParseMsg() { ParseMsgData(); ParseTrailer(); } virtual void ParseMsgData() = 0; ParseTrailer(); }; and derived classes, class InitiateMsg { void ParseMsgData() { ... } }; class ReadOperationMsg { void ParseMsgData() { ... } }; class WriteOperationMsg { void ParseMsgData() { ... } }; and the scenario is below, void UsageFunction(string data) { Msg* msg = ParseHeader(data); ParseMsg } Msg* ParseHeader(string data) { Msg *msg = NULL; .... switch() { case 1: msg = new InitiateMsg(); break; case 2: msg = new ReadOperationMsg{(); break; case 3: msg = new WriteOperationMsg{(); break; .... } return msg; } based on the data ParseHeader method will decide which object has to be created, So I have implemented ParseHeader function outside the class where I am using. How can I make the ParseHeader function inside the Msg class and then use it? In C# the same is achieved by defining ParseHeader method as static with in class and use it from outside,

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  • Events convention - I don't get it

    - by bobjink
    My class with an event: public class WindowModel { public delegate void WindowChangedHandler(object source, WindowTypeEventArgs e); public event WindowChangedHandler WindowChanged; public void GotoWindow(WindowType windowType) { this.currentWindow = windowType; this.WindowChanged.Invoke(this, new WindowTypeEventArgs(windowType)); } } Derived event class: public class WindowTypeEventArgs : EventArgs { public readonly WindowType windowType; public WindowTypeEventArgs(WindowType windowType) { this.windowType = windowType; } } Some other class that register it to the event: private void SetupEvents() { this.WindowModel.WindowChanged += this.ChangeWindow; } private void ChangeWindow(object sender, WindowTypeEventArgs e) { //change window } What have I gained from following the .Net convention? It would make more sense to have a contract like this public delegate void WindowChangedHandler(WindowType windowType); public event WindowChangedHandler WindowChanged; Doing it this way, I don't need to create a new class and is easier to understand. I am not coding a .Net library. This code is only going to be used in this project. I like conventions but am I right when I say that in this example it does not make sense or have i missunderstood something?

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  • NDK app onDestroy cleanup - how to DetachCurrentThread

    - by Aristarhys
    So if we attach we must detach thread after after it finish, right? JNIEnv* get_jni_env() { JNIEnv* res; JAVA_VM->GetEnv((void**) &res, JNI_VERSION_1_6);//Using cached JavaVM JAVA_VM->AttachCurrentThread(&res, NULL); return res; } I call next native method from @Override protected void onDestroy() of my Activity class void free_jni_manager() { JNIEnv* env = get_jni_env(); ... //Here i delete global refs (jclass) //JAVA_VM->DetachCurrentThread(); } ERROR: detaching thread with interp frames (count=16) - main thread still running and we try to detach it. Even if we take any function that use JNIEnv (for example calling java methods), putting DetachCurrentThread will cause same error. DetachCurrentThread works flawlessly if used in pthread function static void* thread_func(void* arg) { get_jni_env(); // attach new thread //Do thread stuff JAVA_VM->DetachCurrentThread();//thread done detached it with ok return NULL; } Do we need detach main thread then we done with JNI, there do it? Or then activity will be destroyed, it will freed itself with JavaVM? Do we need do call DestroyJavaVM() (just doing crash if use onDestroy), how free cached JavaVM or garbage cleaner will handle this? P.S. What benefits of using AttachCurrentThreadAsDaemon()

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  • maximum of given function

    - by davit-datuashvili
    first of all i am doing programs in java language this code is merely taken from web site i have not question about divide and conqurer but about function and it's argument here is code of ternary search def ternarySearch(f, left, right, absolutePrecision): #left and right are the current bounds; the maximum is between them if (right - left) < absolutePrecision: return (left + right)/2 leftThird = (2*left + right)/3 rightThird = (left + 2*right)/3 if f(leftThird) < f(rightThird): return ternarySearch(f, leftThird, right, absolutePrecision) return ternarySearch(f, left, rightThird, absolutePrecision) i am not asking once again how implement it in java i am asking for example how define function?for example let y=x^+3 yes we can determine it as public static int y(int x){ return x*x+3; } but here return ternarySearch(f, leftThird, right, absolutePrecision) function f does not have argument and how do such?please help me

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  • How to control manager class in Blackberry

    - by Keng
    Dear All, I have a problem when creating a UI on Blackberry. First, i try to create a ChatLayoutManager class extended from Manager class. My layout has three component: topfield, mainfield and bottom field. public class ChatLayoutManager extends Manager { private Field bottomField; private Field mainField; private Field titleField; public ChatLayoutManager(long style) { super(style); } protected void sublayout(int width, int height) { setExtent(width, height); int y = 0; if (bottomField != null) { layoutChild(bottomField, width, height); // This goes at the bottom of the screen setPositionChild(bottomField, 0, height-bottomField.getHeight()); height -= bottomField.getHeight(); } if (titleField != null) { layoutChild(titleField, width, height); // This goes at the top of the screen setPositionChild(titleField, 0, 0); height -= titleField.getHeight(); y += titleField.getHeight(); } if (mainField != null) { layoutChild(mainField, width, height); // This goes just below the title field (if any) setPositionChild(mainField, 0, y); } } public void setMainField(Field f) { mainField = f; add(f); } public void setBottomField(Field f) { bottomField = f; add(f); } public void setTitleField(Field f) { titleField = f; add(f); } Then i create another field (ChatField) extended from manager to add to mainfield in the ChatLayoutManager class which i have created above. public class ChatField extends Manager{ private Field _contentField[]; protected ChatField(){ super(Manager.HORIZONTAL_SCROLL | Manager.VERTICAL_SCROLL); } // TODO Auto-generated constructor stub} protected synchronized void sublayout(int width, int height) { // TODO Auto-generated method stub setExtent(width, height); int x = 0; int y = 0; if(_contentField.length > 0){ for(int i = 0 ;i<_contentField.length; i++){ //if(getManager() == this){ this.layoutChild(_contentField[i], _contentField[i].getWidth(), _contentField[i].getHeight()); this.setPositionChild(_contentField[i], x, y); if(_contentField[i++]!= null){ if ((_contentField[i].getWidth() + _contentField[i].getWidth()) >= width){ x = 0; y += _contentField[i].getHeight(); } else{ x += _contentField[i].getWidth(); } } //} } } } public void setContentField(Field field[]){ _contentField = field; } } And now, when i create some fields(such as TextField, BitmapField ...) added to ChatField, the program has an error "Field is not a child of this manager". The reason is when the framework invokes the sublayout function of the ChatField class , when sublayout starts calling layoutChild function the manager of field is not ChatField but ChatlayoutManager. I've experience hard time trying to resolve this problem, still I have no solution. Anybody can give me some suggestions? I really appreciate.

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  • Pointer inside a struct / thread

    - by bruno
    Hi! I have this warning "warning: assignment from incompatible pointer type " in this line: data1->transformed_block[l] = &transformed_block[l]; - void print_message_function ( void *ptr ) { dt *data; data = (dt *) ptr; printf("Dentro da thread Numero0: %ld\n", data->L_norm_NewBlock); pthread_exit(0); } typedef struct data_thread { long L_norm_NewBlock; int Bsize_X; int Bsize_Y; int *transformed_block[MAX_LEVEL]; long L_norm_OrigBlock; } dt; void function() { int *transformed_block[MAX_LEVEL]; pthread_t thread1; dt *data1; pthread_attr_t attr; pthread_attr_init(&attr); //Fills structure data1 = (dt *) malloc(sizeof(dt)); data1->transformed_block[l] = &transformed_block[l]; data1->L_norm_NewBlock=0; data1->Bsize_Y = Bsize_Y; data1->Bsize_X = Bsize_X; pthread_create(&thread1, &attr, (void *) &print_message_function, (void *) &data1); } I want to get rid of that warning, and the values i get inside the thread are wrong. For example data1-L_norm_NewBlock=0; in the thread guives me a differente value (not 0 like it should be).

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  • Combining the value of GetLastError and a custom error message

    - by Jessica
    I have a function that returns a different DWORD value for each case there is an error. So I have the following defines: #define ERR_NO_DB_CONNECTION 0x90000 #define ERR_DB_NOT_OPEN 0x90001 #define ERR_DB_LOCKED 0x90002 #define ERR_DB_CONN_LOST 0x90003 Now, I return those values when an error occurs. I need to also return the value of GetLastError in the same return. No, I can't read it later. I tried combining it different ways, eg: return ERR_DB_NOT_OPEN + GetLastError(); and then extract the error by subtracting the value of ERR_DB_NOT_OPEN but since I need to use this in functions where there can be several return values it can get quite complex to do that. Is there any way to achieve this? I mean, combine the value + GetLastError and extract them later? Code is appreciated. Thanks Jess.

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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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  • 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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  • C# Design Reduce a Long List of Methods

    - by guazz
    I have a simple application that loads data from an XML file to a database. public class EmployeeLoader() { public void LoadEmpoyees() {...} public void LoadSalaries() {...} public void LoadRegistrationData() {...} public void LoadTaxData() {...} } Is it a good idea to have multiple "Load" methods as this looks like a code smell as I have about tweney Load methods? If so, how do I make my code more readable? Each Load method loads data to the corresponding table in the database via a repository?

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  • How to call a method after asynchronous task is complete

    - by doctordoder
    I have a class called WikiWebView which is a subclass of UIWebView which loads Wikipedia subjects and is designed to fetch all the links of the webpage, in order to create a sort of site map for the subject. My problem is that I can only create the links once the web page has loaded, but the loading isn't done right after [self loadRequest:requestObj] is called. - (void)loadSubject:(NSString *)subject { // load the actual webpage NSString *wiki = @"http://www.wikipedia.org/wiki/"; NSString *fullURL = [wiki stringByAppendingString:subject]; NSURL *url = [NSURL URLWithString:fullURL]; NSURLRequest *requestObj = [NSURLRequest requestWithURL:url]; [self loadRequest:requestObj]; // [self createLinks]; // need this to be called after the view has loaded } - (void)createLinks { NSString *javascript = @"var string = \"\";" "var arr = document.getElementsByClassName(\"mw-redirect\");" "for (var i = 0; i < arr.length; ++i)" "{" "var redirectLink = arr[i].href;" "string = string + redirectLink + \" \";" "}" "string;"; NSString *links = [self stringByEvaluatingJavaScriptFromString:javascript]; self.links = [links componentsSeparatedByString:@" "]; } I tried the normal delegation technique, which lead to this code being added: - (id)init { if (self = [super init]) { self.delegate = self; // weird } return self; } #pragma mark - UIWebViewDelegate - (void)webViewDidStartLoad:(UIWebView *)webView { ++_numProcesses; } - (void)webView:(UIWebView *)webView didFailLoadWithError:(NSError *)error { --_numProcesses; } - (void)webViewDidFinishLoad:(UIWebView *)webView { --_numProcesses; if (_numProcesses == 0) { [self createLinks]; } } However, the delegate methods are never called.. I've seen similar questions where the answers are to use blocks, but how would I do that in this case?

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  • Android: Unable to access a local website over HTTPS

    - by user1253789
    I am trying to access a locally hosted website and get its HTML source to parse. I have few questions: 1) Can I use "https://An IP ADDRESS HERE" as a valid URL to try and access. I do not want to make changes in the /etc/hosts file so I want to do it this way. 2) I cannot get the html, since it is giving me Handshake exceptions and Certificate issues. I have tried a lot of help available over the web , but am not successful. Here is the code I am using: public class MainActivity extends Activity { private TextView textView; String response = ""; String finalresponse=""; /** Called when the activity is first created. */ @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); textView = (TextView) findViewById(R.id.TextView01); System.setProperty("javax.net.ssl.trustStore","C:\\User\\*" ); System.setProperty("javax.net.ssl.trustStorePassword", "" ); } private class DownloadWebPageTask extends AsyncTask<String, Void, String> { @Override protected String doInBackground(String... urls) { TrustManager[] trustAllCerts = new TrustManager[] { new X509TrustManager() { public java.security.cert.X509Certificate[] getAcceptedIssuers() { return null; } public void checkClientTrusted(java.security.cert.X509Certificate[] certs, String authType) { } public void checkServerTrusted(java.security.cert.X509Certificate[] certs, String authType) { } } }; try { SSLContext sc = SSLContext.getInstance("SSL"); sc.init(null, trustAllCerts, new java.security.SecureRandom()); HttpsURLConnection.setDefaultSSLSocketFactory(sc.getSocketFactory()); } catch (Exception e) { } try { URL url = new URL("https://172.27.224.133"); HttpsURLConnection con =(HttpsURLConnection)url.openConnection(); con.setHostnameVerifier(new AllowAllHostnameVerifier()); finalresponse=readStream(con.getInputStream()); } catch (Exception e) { e.printStackTrace(); } return finalresponse; } private String readStream(InputStream in) { BufferedReader reader = null; try { reader = new BufferedReader(new InputStreamReader(in)); String line = ""; while ((line = reader.readLine()) != null) { response+=line; } } catch (IOException e) { e.printStackTrace(); } finally { if (reader != null) { try { reader.close(); } catch (IOException e) { e.printStackTrace(); } } } return response; } @Override protected void onPostExecute(String result) { textView.setText(finalresponse); } } public void readWebpage(View view) { DownloadWebPageTask task = new DownloadWebPageTask(); task.execute(new String[] { "https://172.27.224.133" }); } }

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  • Java AD Authentication across Trusted Domains

    - by benjiisnotcool
    I am trying to implement Active Directory authentication in Java which will be ran from a Linux machine. Our AD set-up will consist of multiple servers that share trust relationships with one another so for our test environment we have two domain controllers: test1.ad1.foo.com who trusts test2.ad2.bar.com. Using the code below I can successfully authenticate a user from test1 but not on test2: public class ADDetailsProvider implements ResultSetProvider { private String domain; private String user; private String password; public ADDetailsProvider(String user, String password) { //extract domain name if (user.contains("\\")) { this.user = user.substring((user.lastIndexOf("\\") + 1), user.length()); this.domain = user.substring(0, user.lastIndexOf("\\")); } else { this.user = user; this.domain = ""; } this.password = password; } /* Test from the command line */ public static void main (String[] argv) throws SQLException { ResultSetProvider res = processADLogin(argv[0], argv[1]); ResultSet results = null; res.assignRowValues(results, 0); System.out.println(argv[0] + " " + argv[1]); } public boolean assignRowValues(ResultSet results, int currentRow) throws SQLException { // Only want a single row if (currentRow >= 1) return false; try { ADAuthenticator adAuth = new ADAuthenticator(); LdapContext ldapCtx = adAuth.authenticate(this.domain, this.user, this.password); NamingEnumeration userDetails = adAuth.getUserDetails(ldapCtx, this.user); // Fill the result set (throws SQLException). while (userDetails.hasMoreElements()) { Attribute attr = (Attribute)userDetails.next(); results.updateString(attr.getID(), attr.get().toString()); } results.updateInt("authenticated", 1); return true; } catch (FileNotFoundException fnf) { Logger.getAnonymousLogger().log(Level.WARNING, "Caught File Not Found Exception trying to read cris_authentication.properties"); results.updateInt("authenticated", 0); return false; } catch (IOException ioe) { Logger.getAnonymousLogger().log(Level.WARNING, "Caught IO Excpetion processing login"); results.updateInt("authenticated", 0); return false; } catch (AuthenticationException aex) { Logger.getAnonymousLogger().log(Level.WARNING, "Caught Authentication Exception attempting to bind to LDAP for [{0}]", this.user); results.updateInt("authenticated", 0); return true; } catch (NamingException ne) { Logger.getAnonymousLogger().log(Level.WARNING, "Caught Naming Exception performing user search or LDAP bind for [{0}]", this.user); results.updateInt("authenticated", 0); return true; } } public void close() { // nothing needed here } /** * This method is called via a Postgres function binding to access the * functionality provided by this class. */ public static ResultSetProvider processADLogin(String user, String password) { return new ADDetailsProvider(user, password); } } public class ADAuthenticator { public ADAuthenticator() throws FileNotFoundException, IOException { Properties props = new Properties(); InputStream inStream = this.getClass().getClassLoader(). getResourceAsStream("com/bar/foo/ad/authentication.properties"); props.load(inStream); this.domain = props.getProperty("ldap.domain"); inStream.close(); } public LdapContext authenticate(String domain, String user, String pass) throws AuthenticationException, NamingException, IOException { Hashtable env = new Hashtable(); this.domain = domain; env.put(Context.INITIAL_CONTEXT_FACTORY, com.sun.jndi.ldap.LdapCtxFactory); env.put(Context.PROVIDER_URL, "ldap://" + test1.ad1.foo.com + ":" + 3268); env.put(Context.SECURITY_AUTHENTICATION, simple); env.put(Context.REFERRAL, follow); env.put(Context.SECURITY_PRINCIPAL, (domain + "\\" + user)); env.put(Context.SECURITY_CREDENTIALS, pass); // Bind using specified username and password LdapContext ldapCtx = new InitialLdapContext(env, null); return ldapCtx; } public NamingEnumeration getUserDetails(LdapContext ldapCtx, String user) throws NamingException { // List of attributes to return from LDAP query String returnAttributes[] = {"ou", "sAMAccountName", "givenName", "sn", "memberOf"}; //Create the search controls SearchControls searchCtls = new SearchControls(); searchCtls.setReturningAttributes(returnAttributes); //Specify the search scope searchCtls.setSearchScope(SearchControls.SUBTREE_SCOPE); // Specify the user to search against String searchFilter = "(&(objectClass=*)(sAMAccountName=" + user + "))"; //Perform the search NamingEnumeration answer = ldapCtx.search("dc=dev4,dc=dbt,dc=ukhealth,dc=local", searchFilter, searchCtls); // Only care about the first tuple Attributes userAttributes = ((SearchResult)answer.next()).getAttributes(); if (userAttributes.size() <= 0) throw new NamingException(); return (NamingEnumeration) userAttributes.getAll(); } From what I understand of the trust relationship, if trust1 receives a login attempt for a user in trust2, then it should forward the login attempt on to it and it works this out from the user's domain name. Is this correct or am I missing something or is this not possible using the method above? --EDIT-- The stack trace from the LDAP bind is {java.naming.provider.url=ldap://test1.ad1.foo.com:3268, java.naming.factory.initial=com.sun.jndi.ldap.LdapCtxFactory, java.naming.security.authentication=simple, java.naming.referral=follow} 30-Oct-2012 13:16:02 ADDetailsProvider assignRowValues WARNING: Caught Authentication Exception attempting to bind to LDAP for [trusttest] Auth error is [LDAP: error code 49 - 80090308: LdapErr: DSID-0C0903A9, comment: AcceptSecurityContext error, data 52e, v1db0]

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  • How solve consumer/producer task using semaphores

    - by user1074896
    I have SimpleProducerConsumer class that illustrate consumer/producer problem (I am not sure that it's correct). public class SimpleProducerConsumer { private Stack<Object> stack = new Stack<Object>(); private static final int STACK_MAX_SIZE = 10; public static void main(String[] args) { SimpleProducerConsumer pc = new SimpleProducerConsumer(); new Thread(pc.new Producer(), "p1").start(); new Thread(pc.new Producer(), "p2").start(); new Thread(pc.new Consumer(), "c1").start(); new Thread(pc.new Consumer(), "c2").start(); new Thread(pc.new Consumer(), "c3").start(); } public synchronized void push(Object d) { while (stack.size() >= STACK_MAX_SIZE) try { wait(); } catch (InterruptedException e) { e.printStackTrace(); } try { Thread.sleep(1000); } catch (InterruptedException e) { e.printStackTrace(); } stack.push(new Object()); System.out.println("push " + Thread.currentThread().getName() + " " + stack.size()); notify(); } public synchronized Object pop() { while (stack.size() == 0) try { wait(); } catch (InterruptedException e) { e.printStackTrace(); } try { Thread.sleep(50); } catch (InterruptedException e) { e.printStackTrace(); } stack.pop(); System.out.println("pop " + Thread.currentThread().getName() + " " + stack.size()); notify(); return null; } class Consumer implements Runnable { @Override public void run() { while (true) { pop(); } } } class Producer implements Runnable { @Override public void run() { while (true) { push(new Object()); } } } } I found simple realization of semaphore(here:http://docs.oracle.com/javase/tutorial/essential/concurrency/guardmeth.html I know that there is concurrency package) How I need to change code to exchange java objects monitors to my custom semaphore. (To illustrate C/P problem using semaphores) Semaphore: class Semaphore { private int counter; public Semaphore() { this(0); } public Semaphore(int i) { if (i < 0) throw new IllegalArgumentException(i + " < 0"); counter = i; } public synchronized void release() { if (counter == 0) { notify(); } counter++; } public synchronized void acquire() throws InterruptedException { while (counter == 0) { wait(); } counter--; } }

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  • DoWork of BackgroundWorker is called twice when RunWorkerAsync is called once?

    - by Power-Mosfet
    I have create a backgroundworker in an class it works, but if i call and wait until the end run, call it for the second time it will do the same process twice i thinks there is somthing wrong with bw.DoWork += private void button1_Click(object sender, EventArgs e) { nptest.test.start("null", "null"); } namespace nptest { class test { public static void start(string str, string strb) { if (bw.IsBusy != true) { bw.WorkerSupportsCancellation = true; bw.DoWork += (obj, e) => bw_DoWork(str, strb); bw.RunWorkerCompleted += new RunWorkerCompletedEventHandler(bw_RunWorkerCompleted); bw.RunWorkerAsync(); } } private static BackgroundWorker bw = new BackgroundWorker(); private static void bw_DoWork(string str, string strb) { System.Windows.Forms.MessageBox.Show("initializing BackgroundWorker"); } private static void bw_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e) { if ((e.Cancelled == true)) { Console.WriteLine("Canceled"); } else if (!(e.Error == null)) { Console.WriteLine("Error: " + e.Error.Message); } bw.Dispose(); } } }

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  • Question about C++ inner class

    - by michael
    HI, In C++ inner class, class A { public: void f1(); private: void f2(); class B { private void f3(); }; } Does an inner class (B) has a pointer to its parent class (A)? (like it does in Java). And can B calls its parent class public/private method (like it does in Java). Thank you.

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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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  • Best ways to write a method that updates two objects in a multithreaded java environment?

    - by DanielHonig
    Suppose we have a class called AccountService that manages the state of accounts. AccountService is defined as interface AccountService{ public void debit(account); public void credit(account); public void transfer(Account account, Account account1); } Given this definition, what is the best way to implement transfer() so that you can guarantee that transfer is an atomic operation. I'm interested in answers that reference Java 1.4 code as well as answers that might use resources from java.util.concurrent in Java 5

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  • How do I add a function to an element via jQuery?

    - by Chad Johnson
    I want to do something like this: $('.dynamicHtmlForm').validate = function() { return true; } $('.dynamicHtmlForm .saveButton').click(function() { if (!$(this).closest('.dynamicHtmlForm').validate()) { return false; } return true; }); And then when I have a form of class dynamicHtmlForm, I want to be able to provide a custom validate() function: $('#myDynamicHtmlForm').validate = function() { // do some validation if (there are errors) { return false; } return true; } But I get this when I do this: $(this).closest(".dynamicHtmlForm").validate is not a function Is what I've described even possible? If so, what am I doing wrong?

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  • Win32 reset event like synchronization class with boost C++

    - by fgungor
    I need some mechanism reminiscent of Win32 reset events that I can check via functions having the same semantics with WaitForSingleObject() and WaitForMultipleObjects() (Only need the ..SingleObject() version for the moment) . But I am targeting multiple platforms so all I have is boost::threads (AFAIK) . I came up with the following class and wanted to ask about the potential problems and whether it is up to the task or not. Thanks in advance. class reset_event { bool flag, auto_reset; boost::condition_variable cond_var; boost::mutex mx_flag; public: reset_event(bool _auto_reset = false) : flag(false), auto_reset(_auto_reset) { } void wait() { boost::unique_lock<boost::mutex> LOCK(mx_flag); if (flag) return; cond_var.wait(LOCK); if (auto_reset) flag = false; } bool wait(const boost::posix_time::time_duration& dur) { boost::unique_lock<boost::mutex> LOCK(mx_flag); bool ret = cond_var.timed_wait(LOCK, dur) || flag; if (auto_reset && ret) flag = false; return ret; } void set() { boost::lock_guard<boost::mutex> LOCK(mx_flag); flag = true; cond_var.notify_all(); } void reset() { boost::lock_guard<boost::mutex> LOCK(mx_flag); flag = false; } }; Example usage; reset_event terminate_thread; void fn_thread() { while(!terminate_thread.wait(boost::posix_time::milliseconds(10))) { std::cout << "working..." << std::endl; boost::this_thread::sleep(boost::posix_time::milliseconds(1000)); } std::cout << "thread terminated" << std::endl; } int main() { boost::thread worker(fn_thread); boost::this_thread::sleep(boost::posix_time::seconds(1)); terminate_thread.set(); worker.join(); return 0; } EDIT I have fixed the code according to Michael Burr's suggestions. My "very simple" tests indicate no problems. class reset_event { bool flag, auto_reset; boost::condition_variable cond_var; boost::mutex mx_flag; public: explicit reset_event(bool _auto_reset = false) : flag(false), auto_reset(_auto_reset) { } void wait() { boost::unique_lock<boost::mutex> LOCK(mx_flag); if (flag) { if (auto_reset) flag = false; return; } do { cond_var.wait(LOCK); } while(!flag); if (auto_reset) flag = false; } bool wait(const boost::posix_time::time_duration& dur) { boost::unique_lock<boost::mutex> LOCK(mx_flag); if (flag) { if (auto_reset) flag = false; return true; } bool ret = cond_var.timed_wait(LOCK, dur); if (ret && flag) { if (auto_reset) flag = false; return true; } return false; } void set() { boost::lock_guard<boost::mutex> LOCK(mx_flag); flag = true; cond_var.notify_all(); } void reset() { boost::lock_guard<boost::mutex> LOCK(mx_flag); flag = false; } };

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  • how to exit recursive math formula and still get an answer

    - by calccrypto
    i wrote this python code, which from wolfram alpha says that its supposed to return the factorial of any positive value (i probably messed up somewhere), integer or not: from math import * def double_factorial(n): if int(n) == n: n = int(n) if [0,1].__contains__(n): return 1 a = (n&1) + 2 b = 1 while a<=n: b*=a a+= 2 return float(b) else: return factorials(n/2) * 2**(n/2) *(pi/2)**(.25 *(-1+cos(n * pi))) def factorials(n): return pi**(.5 * sin(n*pi)**2) * 2**(-n + .25 * (-1 + cos(2*n*pi))) * double_factorial(2*n) the problem is , say i input pi to 6 decimal places. 2*n will not become a float with 0 as its decimals any time soon, so the equation turns out to be pi**(.5 * sin(n*pi)**2) * 2**(-n + .25 * (-1 + cos(2*n*pi))) * double_factorial(loop(loop(loop(...))))) how would i stop the recursion and still get the answer? ive had suggestions to add an index to the definitions or something, but the problem is, if the code stops when it reaches an index, there is still no answer to put back into the previous "nests" or whatever you call them

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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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  • 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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