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  • Java: What are the various available security settings for applets

    - by bguiz
    I have an applet that throws this exception when trying to communicate with the server (running on localhost). This problem is limited to Applets only - a POJO client is able to communicate with the exact same server without any problem. Exception in thread "AWT-EventQueue-1" java.security.AccessControlException: access denied (java.net .SocketPermission 127.0.0.1:9999 connect,resolve) at java.security.AccessControlContext.checkPermission(AccessControlContext.java:323) My applet.policy file's contents is: grant { permission java.security.AllPermission; }; My question is what are the other places where I need to modify my security settings to grant an Applet more security settings? Thank you. EDIT: Further investigation has lead me to find that this problem only occurs on some machines - but not others. So it could be a machine level (global) setting that is causing this, rather than a application-specific setting such as the one in the applet.policy file. EDIT: Another SO question: Socket connection to originating server of an unsigned Java applet This seems to describe the exact same problem, and Tom Hawtin - tackline 's answer provides the reason why (a security patch released that disallows applets from connecting to localhost). Bearing this in mind, how do I grant the applet the security settings such that in can indeed run on my machine. Also why does it run as-is on other machines but not mine?

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  • Measure heap used by each object in Java

    - by Fazal
    Can some suggest a good a free memory profiling tool which will show memory being used by each object in the heap separately. We are trying to profile our application and I used jconsole but its gives me total memory usage only. I am using Eclipse and OC4J

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  • An alternative to reading input from Java's System.in

    - by dvanaria
    I’m working on the UVa Online Judge problem set archive as a way to practice Java, and as a way to practice data structures and algorithms in general. They give an example input file to submit to the online judge to use as a starting point (it’s the solution to problem 100). Input from the standard input stream (java.lang.System.in) is required as part of any solution on this site, but I can’t understand the implementation of reading from System.in they give in their example solution. It’s true that the input file could consist of any variation of integers, strings, etc, but every solution program requires reading basic lines of text input from System.in, one line at a time. There has to be a better (simpler and more robust) method of gathering data from the standard input stream in Java than this: public static String readLn(int maxLg) { byte lin[] = new byte[maxLg]; int lg = 0, car = -1; String line = “”; try { while (lg < maxLg) { car = System.in.read(); if ((car < 0) || (car == ‘\n’)) { break; } lin[lg++] += car; } } catch (java.io.IOException e) { return (null); } if ((car < 0) && (lg == 0)) { return (null); // eof } return (new String(lin, 0, lg)); } I’m really surprised by this. It looks like something pulled directly from K&R’s “C Programming Language” (a great book regardless), minus the access level modifer and exception handling, etc. Even though I understand the implementation, it just seems like it was written by a C programmer and bypasses most of Java’s object oriented nature. Isn’t there a better way to do this, using the StringTokenizer class or maybe using the split method of String or the java.util.regex package instead?

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  • Connect to a site using proxy code in java

    - by Nithin
    I want to connect to as site through proxy in java.This is the code which I have written public class ConnectThroughProxy { Proxy proxy = new Proxy(Proxy.Type.HTTP, new InetSocketAddress("proxy ip", 8080)); public static void main(String[] args) { try{ URL url = new URL("http://www.rgagnon.com/javadetails/java-0085.html"); URLConnection connection=url.openConnection(); String encoded = new String(Base64.encode(new String("user_name:pass_word").getBytes())); connection.setDoOutput(true); connection.setRequestProperty("Proxy-Authorization","Basic "+encoded); String page=""; String line; StringBuffer tmp = new StringBuffer(); BufferedReader in = new BufferedReader(new InputStreamReader(connection.getInputStream())); while ((line=in.readLine()) != null){ page.concat(line + "\n"); } System.out.println(page); }catch(Exception ex){ ex.printStackTrace(); } } while trying to run this code it throws the following error java.lang.IllegalArgumentException: Illegal character(s) in message header value: Basic dXNlcl9uYW1lOnBhc3Nfd29yZA== at sun.net.www.protocol.http.HttpURLConnection.checkMessageHeader(HttpURLConnection.java:323) at sun.net.www.protocol.http.HttpURLConnection.setRequestProperty(HttpURLConnection.java:2054) at test.ConnectThroughProxy.main(ConnectThroughProxy.java:30) Any Idea how to do it.

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  • Trouble with Berkeley DB JE Base API Secondary Databases and Sequences

    - by milosz
    I have a class Document which consists of Id (int) and Url (String). I would like to have a primary index on Id and secondary index on Url. I would also like to have a sequence for Id auto-incrementation. So I create a SecondaryDatabase and then I create a Sequence. During initialisation of the Sequence I get an exception: Exception in thread "main" java.lang.IllegalArgumentException at com.sleepycat.util.UtfOps.getCharLength(UtfOps.java:137) at com.sleepycat.util.UtfOps.bytesToString(UtfOps.java:259) at com.sleepycat.bind.tuple.TupleInput.readString(TupleInput.java:152) at pl.edu.mimuw.zbd.berkeley.zadanie.rozwiazanie.MyDocumentBiding.entryToObject(MyDocumentBiding.java:12) at pl.edu.mimuw.zbd.berkeley.zadanie.rozwiazanie.MyDocumentBiding.entryToObject(MyDocumentBiding.java:1) at com.sleepycat.bind.tuple.TupleBinding.entryToObject(TupleBinding.java:76) at pl.edu.mimuw.zbd.berkeley.zadanie.rozwiazanie.UrlKeyCreator.createSecondaryKey(UrlKeyCreator.java:20) at com.sleepycat.je.SecondaryDatabase.updateSecondary(SecondaryDatabase.java:835) at com.sleepycat.je.SecondaryTrigger.databaseUpdated(SecondaryTrigger.java:42) at com.sleepycat.je.Database.notifyTriggers(Database.java:2004) at com.sleepycat.je.Cursor.putNotify(Cursor.java:1692) at com.sleepycat.je.Cursor.putInternal(Cursor.java:1616) at com.sleepycat.je.Cursor.putNoOverwrite(Cursor.java:663) at com.sleepycat.je.Sequence.<init>(Sequence.java:188) at com.sleepycat.je.Database.openSequence(Database.java:546) at pl.edu.mimuw.zbd.berkeley.zadanie.rozwiazanie.MyFullTextSearchEngine.init(MyFullTextSearchEngine.java:131) at pl.edu.mimuw.zbd.berkeley.zadanie.testy.MyFullTextSearchEngineTest.main(MyFullTextSearchEngineTest.java:18) It seems that during the initialisation of the sequence the secondary database is forced to update. When I debug the entryToObject method of MyDocumentBiding the bytes that it tries to convert to object seem random. What am I doing wrong?

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  • Switching from Java to .NET from a career change point of view

    - by Joe
    Could anyone share with me their experience with switching from Java to .NET from a career point of view? I've been a Java developer for 12 years and am just getting tired of how fragmented the Java world has become. For my liking, there's just too many frameworks, tools, application servers, etc.. And it seems each new tool just adds complexity and time to even the simplest of projects. I'm not trying to start any wars - I'm just giving you the reason I ask the main question. I've read a few books on .NET and have done one WebForms job. I love the integrated environment and would like to hear how others transitioned from Java to .NET. What I mean by that is did you do it somehow as a contractor or did you join a company as a beginner .NET developer with much Java experience? Personally, I'm ready to take the leap if I can figure out how to not lose too much income in the process (Senior Java developer to beginner .NET developer). I would really appreciate hearing your stories.

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  • java serialization problems with different JVMs

    - by Alberto
    I am having trouble using serialization in Java. I've searched the web for a solution but haven't found an answer yet. The problem is this - I have a Java library (I have the code and I export it to an archive prior to executing the code) which I need to use with two differents JVMs. One JVM is on the server (Ubuntu, running Java(TM) JRE SE Runtime Environment (build 1.7.0_09-b05)) and the other on Android 2.3.3. I compiled the library in Java 1.6. Now, I am trying to import to the client, an object exported from the server, but I receive this error: java.io.InvalidClassException: [Lweka.classifiers.functions.MultilayerPerceptron$NeuralEnd;; Incompatible class (SUID): [Lweka.classifiers.functions.MultilayerPerceptron$NeuralEnd;: static final long serialVersionUID =-359311387972759020L; but expected [Lweka.classifiers.functions.MultilayerPerceptron$NeuralEnd;: static final long serialVersionUID =1920571045915494592L; I do have an explicit serial version UID declared on the class MultilayerPerceptron$NeuralEnd, like this: protected class NeuralEnd extends NeuralConnection { private static final long serialVersionUID = 7305185603191183338L; } Where NeuralConnection implements the java.io.Serializable interface. If I do a serialver on MultilayerPerceptron$NeuralEnd I receive the serialVersionUID which I declared. So, why have both JVMs changed this value? Can you help me? Thanks, Alberto

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  • Singleton pattern and broken double checked locking in real world java application

    - by saugata
    I was reading the article Double-checked locking and the Singleton pattern, on how double checked locking is broken, and some related questions here on stackoverflow. I have used this pattern/idiom several times without any issues. Since I have been using Java 5, my first thought was that this has been rectified in Java 5 memory model. However the article says This article refers to the Java Memory Model before it was revised for Java 5.0; statements about memory ordering may no longer be correct. However, the double-checked locking idiom is still broken under the new memory model. I'm wondering if anyone has actually run into this problem in any application and under what conditions.

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  • Java JList model

    - by Alaa
    How can I make a list model from a JList in order to be able to insert an item into it. I want to use this method: addElement(java.lang.Object item) I found an explanation here, but the problem is that ListModel is an interface and even if I write an implementation and override its method, I can't use the addElement() method

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  • Android OutOfMemoryError - Loading JSON File

    - by jeremynealbrown
    The app I am working on needs to read a JSON file that may be anywhere from 1.5 to 3 MB in size. It seems to have no problem opening the file and converting the data to a string, but when it attempts to convert the string to a JSONArray, OutOfMemoryErrors are thrown. The exceptions look something like this: E/dalvikvm-heap( 5307): Out of memory on a 280-byte allocation. W/dalvikvm( 5307): Exception thrown (Ljava/lang/OutOfMemoryError;) while throwing internal exception (Ljava/lang/OutOfMemoryError;) One strange thing about this is that the crash only occurs every 2nd or 3rd time the app is run, leaving me to believe that the memory consumed by the app is not being garbage collected each time the app closes. Any insight into how I might get around this issue would be greatly appreciated. I am open to the idea of loading the file in chunks, but I'm not quite sure what the best approach is for such a task. Thank you

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  • Does Java Spring 3.0 MVC support annotation/attribute based client side validation like Asp.net MVC

    - by Athens
    In Asp.Net MVC 2.0, at least in the beta, you could decoration your model classes with data annotation attributes and enable client side validation that leverages that criteria defined in your model data annotation attibutes. Is there anything similar for Java Spring MVC 3.0? Is it possible to inject a component into the response pipeline that can inspect the model's annotated properties and render client side validation logic to complement the server side validation logic that is invoked prior to the controller handling the request?

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  • Android Keep Activity from Dieing

    - by GuyNoir
    The main Activity I use in my Android application uses a fair amount of memory, meaning that on a less powerful phone, it is susceptible to being killed off when not at the front. Normally this is fine, but it also happens when I am still inside my application, but have a different activity at the top of the stack (such as a preference activity). Obviously it's a problem if my application is killed while the user is still running it. Is there any way to disable the OS's ability to kill off the application for low memory problems? Thanks.

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  • Is 1/0 a legal Java expression?

    - by polygenelubricants
    The following compiles fine in my Eclipse: final int j = 1/0; // compiles fine!!! // throws ArithmeticException: / by zero at run-time Java prevents many "dumb code" from even compiling in the first place (e.g. "Five" instanceof Number doesn't compile!), so the fact this didn't even generate as much as a warning was very surprising to me. The intrigue deepens when you consider the fact that constant expressions are allowed to be optimized at compile time: public class Div0 { public static void main(String[] args) { final int i = 2+3; final int j = 1/0; final int k = 9/2; } } Compiled in Eclipse, the above snippet generates the following bytecode (javap -c Div0) Compiled from "Div0.java" public class Div0 extends java.lang.Object{ public Div0(); Code: 0: aload_0 1: invokespecial #8; //Method java/lang/Object."<init>":()V 4: return public static void main(java.lang.String[]); Code: 0: iconst_5 1: istore_1 // "i = 5;" 2: iconst_1 3: iconst_0 4: idiv 5: istore_2 // "j = 1/0;" 6: iconst_4 7: istore_3 // "k = 4;" 8: return } As you can see, the i and k assignments are optimized as compile-time constants, but the division by 0 (which must've been detectable at compile-time) is simply compiled as is. javac 1.6.0_17 behaves even more strangely, compiling silently but excising the assignments to i and k completely out of the bytecode (probably because it determined that they're not used anywhere) but leaving the 1/0 intact (since removing it would cause an entirely different program semantics). So the questions are: Is 1/0 actually a legal Java expression that should compile anytime anywhere? What does JLS say about it? If this is legal, is there a good reason for it? What good could this possibly serve?

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  • Some help required while working on Java and Cygwin together

    - by Hippo
    Hello .. I am new to java and also cygwin . I do not have in detailed knowledge of both . I need some help.. I simple steps i will try to explain my problem. 1) I am working on tinyOS . its open source OS , used for wireless sensor networks. It provides java libraries to work on communication (PC to sensor) 2) I am working on windows xp environment through cigwin. 3) I am developing an application . THis application requires one java interface called "Serial Forwarder" , which is readily available in libraries provided. Previously i used to start this interface manually (by entering command *"java net.tinyos.sf.SerialForwarder ")*and then my application which uses this interface. But now i want to make my application independent . User need know about this background cygwin commands . 4) So in my java application i used "Runtime.getRuntime().exec( "java net.tinyos.sf.SerialForwarder)" . 5) This i neither giving any error nor starting the interface. Am I going on right way ? When i am using runtime execute command , how can i make sure that this command is called through cigwin interface ? Also .. if i want to write .bat file .. i which i can give commands which will be executed .. how can i make sure that those commands are given through cigwin .. and not through cmd.exe .. Please help . me .

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  • Rhapsody TestConductor Experiences

    - by vaiomike
    I was wondering whether anybody out there is actively using Rhapsody TestConductor? Or has tried it for a while, but then decided to turn it down for a particular reason? If so, what are your experiences, in which field do you apply it, what are the shortcomings, or why did you turn it down? At the moment we're considering TestConductor as our tool of choice for testing as it's already integrated into Rhapsody, and would like to find out how applicable it is to our project (btw, we're using Rhapsody 7.4 in C). P.S: Recommendations on good books about Model Based Testing are also appreciated.

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  • What situations does a Monostate pattern model?

    - by devoured elysium
    I know what both a Singleton or a Monostate are and how to implement them. Although I can see many uses for a Singleton, I can't imagine a situation where I would want to let the user create as many instances of my class although in reality only one really exists behind the scenes. Can anybody help me here? I know that for several reasons one should stay away from both patterns, but in theory, what kind of problems does the Monostate model? Thanks

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  • Working with mongodb from Java

    - by demas
    I have launch mongodb server: [[email protected]][~]% mongod --dbpatmongod --dbpath /home/demas/temp/ Mon Apr 19 09:44:18 Mongo DB : starting : pid = 4538 port = 27017 dbpath = /home/demas/temp/ master = 0 slave = 0 32-bit ** NOTE: when using MongoDB 32 bit, you are limited to about 2 gigabytes of data ** see http://blog.mongodb.org/post/137788967/32-bit-limitations for more Mon Apr 19 09:44:18 db version v1.4.0, pdfile version 4.5 Mon Apr 19 09:44:18 git version: nogitversion Mon Apr 19 09:44:18 sys info: Linux arch.local.net 2.6.33-ARCH #1 SMP PREEMPT Mon Apr 5 05:57:38 UTC 2010 i686 BOOST_LIB_VERSION=1_41 Mon Apr 19 09:44:18 waiting for connections on port 27017 Mon Apr 19 09:44:18 web admin interface listening on port 28017 I have created documents by console client: [[email protected]][~]% mongo MongoDB shell version: 1.4.0 url: test connecting to: test type "help" for help > db.some.find(); { "_id" : ObjectId("4bcbef3c3be43e9b7e04ef3d"), "name" : "mongo" } { "_id" : ObjectId("4bcbef423be43e9b7e04ef3e"), "x" : 3 } Now I am trying to work with MongoDb from Java: import com.mongodb.*; import java.net.UnknownHostException; public class test1 { public static void main(String[] args) { System.out.println("Start"); try { Mongo m = new Mongo("localhost", 27017); DB db = m.getDB("test"); DBCollection coll = db.getCollection("some"); coll.insert(makeDocument(10, "James", "male")); System.out.println("Finish"); } catch (UnknownHostException ex) { ex.printStackTrace(); } catch (MongoException ex) { ex.printStackTrace(); } } public static BasicDBObject makeDocument(int id, String name, String gender) { BasicDBObject doc = new BasicDBObject(); doc.put("id", id); doc.put("name", name); doc.put("gender", gender); return doc; } } But execution stops on line coll.insert(): [[email protected]][~/dev/study/java/mongodb]% javac test1.java [[email protected]][~/dev/study/java/mongodb]% java test1 Start There are not messages from mogodb server regarding accepted connection. Why?

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  • Calling Java classes from IzPack

    - by bguiz
    I am trying to write an IzPack installer which is able to detect a previously installed version of the application. After finding out that it doesn't really support this feature, I think the only way to do this is through writing a Java class and calling it from IzPack. Tim Williscroft has previously suggested this method: <condition type="java" id="jbossEnv"> <java> <class>au.com.codarra.ela.installer.JBossChecker</class <field>hasJBossEnv</field> </java> <returnvalue type="boolean">true</returnvalue> </condition> However, is it possible to call <java> from somewhere other than a <condition> tag? I want to be able to call it from a <variable> tag. Also, is it possible to call a method from a Java class instead of reading a value of a field? I want to be able to pass parameters to my class. Thank you!

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  • MySQL create memory leak in Tomcat

    - by mabuzer
    I have set a JDBCRealm for web-app inside tomcat, and when I reload it I got this from tomcat: SEVERE: A web application registered the JBDC driver [com.mysql.jdbc.Driver] but failed to unregister it when the web application was stopped. To prevent a memory leak, the JDBC Driver has been forcibly unregistered. I use tomcat 6.0.24, with MySQL Connector 5.1.10,,,

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  • Performance of Java matrix math libraries?

    - by dfrankow
    We are computing something whose runtime is bound by matrix operations. (Some details below if interested.) This experience prompted the following question: Do folk have experience with the performance of Java libraries for matrix math (e.g., multiply, inverse, etc.)? For example: JAMA: http://math.nist.gov/javanumerics/jama/ COLT: http://acs.lbl.gov/~hoschek/colt/ Apache commons math: http://commons.apache.org/math/ I searched and found nothing. Details of our speed comparison: We are using Intel FORTRAN (ifort (IFORT) 10.1 20070913). We have reimplemented it in Java (1.6) using Apache commons math 1.2 matrix ops, and it agrees to all of its digits of accuracy. (We have reasons for wanting it in Java.) (Java doubles, Fortran real*8). Fortran: 6 minutes, Java 33 minutes, same machine. jvisualm profiling shows much time spent in RealMatrixImpl.{getEntry,isValidCoordinate} (which appear to be gone in unreleased Apache commons math 2.0, but 2.0 is no faster). Fortran is using Atlas BLAS routines (dpotrf, etc.). Obviously this could depend on our code in each language, but we believe most of the time is in equivalent matrix operations. In several other computations that do not involve libraries, Java has not been much slower, and sometimes much faster.

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  • ClassNotFoundException com.mysql.jdbc.Driver

    - by Dusk
    This question might have asked here number of times . After doing some google search for the above error and doing some update, I can't understand why I'm still getting that error. I've already put my driver-- mysql-connector-java-5.1.5-bin in the classpath: Java_Home\jre\lib\ Java_Home\jre\lib\ext\ Java_Home\lib and the code which I'm using to connect to mysql database is: try{ Class.forName("com.mysql.jdbc.Driver"); Connection con=DriverManager.getConnection("jdbc:mysql://localhost:3306/mail","root",""); Statement stmt = con.createStatement(); ResultSet rs = stmt.executeQuery("select message_body from deadletter"); String dbtime; while (rs.next()) { dbtime = rs.getString(1); System.out.println(dbtime); } con.close(); } catch (SQLException e) { System.out.println("Connection Failed! Check output console"); e.printStackTrace(); } } and the complete stacktrace of the above exception is: java.lang.ClassNotFoundException: com.mysql.jdbc:Driver at java.net.URLClassLoader$1.run(URLClassLoader.java:200) at java.security.AccessController.doPrivileged(Native Method) at java.net.URLClassLoader.findClass(URLClassLoader.java:307) at java.lang.ClassLoader.loadClass(ClassLoader.java:307) at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301) at java.lang.ClassLoader.loadClass(ClassLoader.java:252) at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:320) at java.lang.Class.forName0(Native Method) at java.lang.Class.forName(Class.java:169) at mail.main(mail.java:114) Now, what's wrong I'm doing here?

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  • Can a variable bu used 2nd time after releasing it?

    - by Jakub
    Hello, I try to understand the memory management in ObjectiveC and still some things are a misery for me. I've got an instance variable: NSMutableArray *postResultsArray; when a button is clicked in the UI I create new array: self.postResultsArray = [NSMutableArray array]; then I add some objects to the array and when the whole operation is done I would like to release the array: [self.postResultsArray release]; (I assume that all the objects stoed in the array will be released along with the array). The problem appears when I click the button again and in the code I want to create the array again with: self.postResultsArray = [NSMutableArray array]; I get: [CFArray release]: message sent to deallocated instance 0x3d9e390 Can't I initialize the same instance variable for the second time? or maybe I should not release it? and if so, why? Thanks!

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  • Memory allocation in java

    - by Girish
    class Someobject { int i=10; } public class OtherObject { public static void main(String args[]) { Someobject obj=new Someobject(); System.out.println(obj.i); } } Please tell me in which section of the memory: This entire code will load. Where will someobject will be stored. Where will obj will be stored Where will i be stored. Thanks every one in advance.

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  • _CrtDumpMemoryLeaks truncated output??

    - by Marin
    Hello, I am trying to use Visual Studio's capability to detect memory leaks, but I keep getting truncated output, like: Dumping objects -> {174} normal block at 0x0099ADB8, 48 bytes long. Data: <h:\najnovije\tru> 68 3A 5C 6E 61 6A 6E 6F 76 69 6A 65 5C 74 72 75 {170} normal block at 0x0099AD58, 32 bytes long. Data: <h:\najnovije\tru> 68 3A 5C 6E 61 6A 6E 6F 76 69 6A 65 5C 74 72 75 Object dump complete. What am I doing wrong? I added #define _CRTDBG_MAP_ALLOC #include <stdlib.h> #include <crtdbg.h> to the beginning of my code. Thank you.

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