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  • C++ Singleton design pattern

    - by Artem Barger
    Recently I've bumped into a realization/implementation of the Singleton design pattern for C++. It has looked like this (I have adopted it from the real life example): // a lot of methods are omitted here class Singleton { public: static Singleton* getInstance( ); ~Singleton( ); private: Singleton( ); static Singleton* instance; }; From this declaration I can deduce that the instance field is initiated on the heap. That means there is a memory allocation. What is completely unclear for me is when exactly the memory is going to be deallocated? Or is there a bug and memory leak? It seems like there is a problem in the implementation. My main question is, how do I implement it in the right way?

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  • Thread-safe use of a singleton's members

    - by Anthony Mastrean
    I have a C# singleton class that multiple classes use. Is access through Instance to the Toggle() method thread-safe? If yes, by what assumptions, rules, etc. If no, why and how can I fix it? public class MyClass { private static readonly MyClass instance = new MyClass(); public static MyClass Instance { get { return instance; } } private int value = 0; public int Toggle() { if(value == 0) { value = 1; } else if(value == 1) { value = 0; } return value; } }

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  • How do I convert a number (as a String) to an array of bytes in Java?

    - by user1795595
    I'm creating a method specific method for a java project i'm working on. The UML given specifies the return type to be of static byte[] that accepts the arguments (String, byte) So far, looks like this: public static byte[] convertNumToDigitArray(String number, byte numDigits) { } This method is supposed to convert a number (as a String) to an array of bytes. The ordering must go from most to least significant digits. For example, if the number String is “732” then index 0 of the array should contain 7. The last argument (numDigits) should match the length of the string passed in. How do I do this?

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  • Generating CMakeLists.txt

    - by vanna
    I got a bunch of C++ sources files and headers. They may use external libraries such as Boost e.g. I am interested in the process of building binaries for Windows and *nix. Makefiles (*nix) and .vcproj (Windows) call compilers with some specifications such as the order of compilation, compilation options and stuff. CMakeLists.txt can be used by CMake to build either makefiles or .vcproj and use very helpful commands such as recursive search of files, automatic linkage with known libraries, installers, variables that can be used in source files... Is there any existing tool that would generate a CMakeLists.txt from specified options ? Options could be like : scan this folder and make a library out of it, then scan this other folder and make an executable and automatically link both with Boost as well along with a user friendly installer with generated INSTALL.txt and README.txt. Something very powerful like that.

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  • CakePHP: How do I change page title from helper?

    - by Zeta Two
    Hello! I'm using a helper for static pages to add a part to the title on every page. Currently I have the following code at the top of every static page: <?php $this->set('title_for_layout', $title->output('Nyheter')); ?> The purpose of $title-output is to append " :: MY WEB SITE NAME". This works fine, but for simplicity I would rather just call: $title->title('Nyheter'); At the top of every page to set the title. The problem is that I can't call $this-set() from within the helper. Is there a way to something like this or am I completely on the wrong path here?

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  • How to find Key and IV value from .Net to PHP

    - by PHP-Prabhu
    Can any one please let me know is there any way to find a solution for the below stuffs. I need to find out the KEY and IV value from the below byte array. the byte array in .net and this has to be convert into KEY(string) and IV(string) via PHP. private static readonly byte[] Key = { 0xda, 0x3c, 0x35, 0x6f, 0xbd, 0xd, 0x87, 0xf0, 0x9a, 0x7, 0x6d, 0xab, 0x7e, 0x82, 0x36, 0xa, 0x1a, 0x5a, 0x77, 0xfe, 0x74, 0xf3, 0x7f, 0xa8, 0xaa, 0x4, 0x11, 0x46, 0x6b, 0x2d, 0x48, 0xa1 }; private static readonly byte[] IV = { 0x6d, 0x2d, 0xf5, 0x34, 0xc7, 0x60, 0xc5, 0x33, 0xe2, 0xa3, 0xd7, 0xc3, 0xf3, 0x39, 0xf2, 0x16 };

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  • How can I link two Java serialised objects back together?

    - by Kidburla
    Sometimes (quite a lot, actually) we get a situation in Java where two objects are pointing to the same thing. Now if we serialise these separately it is quite appropriate that the serialised forms have separate copies of the object as it should be possible to open one without the other. However if we now deserialise them both, we find that they are still separated. Is there any way to link them back together? Example follows. public class Example { private static class ContainerClass implements java.io.Serializable { private ReferencedClass obj; public ReferencedClass get() { return obj; } public void set(ReferencedClass obj) { this.obj = obj; } } private static class ReferencedClass implements java.io.Serializable { private int i = 0; public int get() { return i; } public void set(int i) { this.i = i; } } public static void main(String[] args) throws Exception { //Initialise the classes ContainerClass test1 = new ContainerClass(); ContainerClass test2 = new ContainerClass(); ReferencedClass ref = new ReferencedClass(); //Make both container class point to the same reference test1.set(ref); test2.set(ref); //This does what we expect: setting the integer in one (way of accessing the) referenced class sets it in the other one test1.get().set(1234); System.out.println(Integer.toString(test2.get().get())); //Now serialise the container classes java.io.ObjectOutputStream os = new java.io.ObjectOutputStream(new java.io.FileOutputStream("C:\\Users\\Public\\test1.ser")); os.writeObject(test1); os.close(); os = new java.io.ObjectOutputStream(new java.io.FileOutputStream("C:\\Users\\Public\\test2.ser")); os.writeObject(test2); os.close(); //And deserialise them java.io.ObjectInputStream is = new java.io.ObjectInputStream(new java.io.FileInputStream("C:\\Users\\Public\\test1.ser")); ContainerClass test3 = (ContainerClass)is.readObject(); is.close(); is = new java.io.ObjectInputStream(new java.io.FileInputStream("C:\\Users\\Public\\test2.ser")); ContainerClass test4 = (ContainerClass)is.readObject(); is.close(); //We expect the same thing as before, and would expect a result of 4321, but this doesn't happen as the referenced objects are now separate instances test3.get().set(4321); System.out.println(Integer.toString(test4.get().get())); } }

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  • ignore this test

    - by Name
    http://markitup.jaysalvat.com/downloads/markupsets/wiki/set.js Here is a useful construct when trying to hide variables from the parent namespace. All the code within the function is contained in the private scope of the function, meaning it is allowed. So you've become comfortable with jQuery and would like to learn how to write your own plugins. Great! You're in the right spot. Extending jQuery with plugins and methods is very powerful and can save you and your peers a lot of development time by abstracting your most clever functions into plugins. This post will outline the basics, best practices, and common pitfalls to watch out for as you begin writing your plugin.

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  • Sharing memory between modules

    - by John Holecek
    Hi, I was wondering how to share some memory between different program modules - lets say, I have a main application (exe), and then some module (dll). They both link to the same static library. This static library will have some manager, that provides various services. What I would like to achieve, is to have this manager shared between all application modules, and to do this transparently during the library initialization. Between processes I could use shared memory, but I want this to be shared in the current process only. Could you think of some cross-platform way to do this? Possibly using boost libraries, if they provide some facilities to do this. Only solution I can think of right now, is to use shared library of the respective OS, that all other modules will link to at runtime, and have the manager saved there.

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  • About Leader Board in Javascript (Array) Help Me Please

    - by raulcorrales
    Hi to all. I need help with a score table for my game. -1- I have 4 variables: var Player1Score= 44; var Player2Score= 12; var Player3Score= 45; var Player4Score= 26; --2-- i make a Array: var MyArray=[Player1Score,Player2Score,Player3Score,Player4Score]; --3-- sort the array: MyArray.Sort(); --4-- Print: ----------HIGHSCORES---------- 45 44 26 12 MY QUESTION IS: HOW I CAN PRINT THE NAME OF THE PLAYERS IN ORDER¿? LIKE THIS: ----------HIGHSCORES---------- PLAYER 3 45 PLAYER 1 44 PLAYER 4 26 PLAYER 2 12 THANKS IN ADVANCE. GREETINGS

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  • How to export user input data from python (Tkinter) to excel? [migrated]

    - by mrn
    I am trying to develop a user form in python 2.7.3. Please note that I am a python beginner. I am trying to use xlwt to export data to excel. I want to write values of following variables i.e. a (value to write:'x1') & d (value to write: be user defined information in text box), to an excel sheet, a=StringVar() checkBox1=Checkbutton(root, text="text1", variable=a, onvalue="x1", offvalue="N/A") checkBox1.place(relx=0., rely=0., relwidth=0., relheight=0.) checkBox1.pack() d=StringVar() atextBox1=Entry(root, textvariable=d, font = '{MS Sans Serif} 10') atextBox1.pack()

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  • Evaluation of (de)reference operators

    - by Micha
    I have an (uncommented...) source file which I'm trying to understand. static const Map *gCurMap; static std::vector<Map> mapVec; then auto e = mapVec.end(); auto i = mapVec.begin(); while(i!=e) { // ... const Map *map = gCurMap = &(*(i++)); // ... } I don't understand what &(*(i++)) does. It does not compile when just using i++, but to me it looks the same, because I'm "incrementing" i, then I'm requesting the value at the given address and then I'm requesting the address of this value?!

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  • Random List of numbers in C

    - by Ant
    I have just started a C programming course and so far have only done the basics like printf, read a little on variables etc on the course book. The teacher has tasked us with writing a program that will take a value entered by the user, this will be the number of students in the class (25 at the moment but can be variable). It will then list the number of students randomly and place them in 3 columns. The purpose is to sort students into groups of 3 randomly, then display on the screen in columns. Now my question is not for the code that defeats the object of me attempting the exercise, but how to structure it. I can see that using an array can be used to display the list, but really after some pointers on how best to approach the problem in blocks, then I can attempt to program each block.

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  • JAVA-SQL- Data Migration - ResultSets comparing Failing JUnit test

    - by user1865053
    I CANNOT get this JUnit Test to pass for the life of me. Can somebody point out where this has gone wrong. I am doing a data migration(MSSQL SERVER 2005), but I have the sourceDBUrl and the targetDCUrl the same URL so to narrow it down to syntax errors. So that is what I have, a syntax error. I am comparing the results of a table for the query SELECT programmeapproval, resourceapproval FROM tr_timesheet WHERE timesheetid = ? and the test always fails, but passes for other junit tests I have developed. I created 3 diffemt resultSetsEqual methods and none work. Yet, some other JUnit tests I have developed have PASSED. THE QUERY: SELECT timesheetid, programmeapproval, resourceapproval FROM tr_timesheet Returns three columns timesheetid (PK,int, not null) (populated with a range of numbers 2240 - 2282) programmeapproval (smallint,not null) (populated with the number 1 in every field) resourceapproval (smallint, not null) (populated with a number 1 in every field) When I run the query that is embedded in the code it only returns one row with the programmeapproval and resourceapproval columns and both field populated with the number 1. I have all jdbc drivers correctly installed and tested for connectivity. The JUnit Test is failing at this point according to the IDE. assertTrue(helper.resultSetsEqual2(sourceVal,targetVal)); This is the code: /*THIS IS A JUNIT CLASS****? package a7.unittests.dao; import static org.junit.Assert.assertTrue; import java.sql.Connection; import java.sql.PreparedStatement; import java.sql.ResultSet; import java.sql.Types; import org.junit.Test; import artemispm.tritonalerts.TimesheetAlert; public class UnitTestTimesheetAlert { @Test public void testQUERY_CHECKALERT() throws Exception{ UnitTestHelper helper = new UnitTestHelper(); Connection con = helper.getConnection(helper.sourceDBUrl); Connection conTarget = helper.getConnection(helper.targetDBUrl); PreparedStatement stmt = con.prepareStatement("select programmeapproval, resourceapproval from tr_timesheet where timesheetid = ?"); stmt.setInt(1, 2240); ResultSet sourceVal = stmt.executeQuery(); stmt = conTarget.prepareStatement("select programmeapproval, resourceapproval from tr_timesheet where timesheetid = ?"); stmt.setInt(1,2240); ResultSet targetVal = stmt.executeQuery(); assertTrue(helper.resultSetsEqual2(sourceVal,targetVal)); }} /*END**/ /*THIS IS A REGULAR CLASS**/ package a7.unittests.dao; import java.sql.Connection; import java.sql.DriverManager; import java.sql.ResultSet; import java.sql.ResultSetMetaData; import java.sql.SQLException; public class UnitTestHelper { static String sourceDBUrl = "jdbc:sqlserver://127.0.0.1:1433;databaseName=a7itm;user=a7user;password=a7user"; static String targetDBUrl = "jdbc:sqlserver://127.0.0.1:1433;databaseName=a7itm;user=a7user;password=a7user"; public Connection getConnection(String url)throws Exception{ return DriverManager.getConnection(url); } public boolean resultSetsEqual3 (ResultSet rs1, ResultSet rs2) throws SQLException { int col = 1; //ResultSetMetaData metadata = rs1.getMetaData(); //int count = metadata.getColumnCount(); while (rs1.next() && rs2.next()) { final Object res1 = rs1.getObject(col); final Object res2 = rs2.getObject(col); // Check values if (!res1.equals(res2)) { throw new RuntimeException(String.format("%s and %s aren't equal at common position %d", res1, res2, col)); } // rs1 and rs2 must reach last row in the same iteration if ((rs1.isLast() != rs2.isLast())) { throw new RuntimeException("The two ResultSets contains different number of columns!"); } } return true; } public boolean resultSetsEqual (ResultSet source, ResultSet target) throws SQLException{ while(source.next()) { target.next(); ResultSetMetaData metadata = source.getMetaData(); int count = metadata.getColumnCount(); for (int i =1; i<=count; i++) { if(source.getObject(i) != target.getObject(i)) { return false; } } } return true; } public boolean resultSetsEqual2 (ResultSet source, ResultSet target) throws SQLException{ while(source.next()) { target.next(); ResultSetMetaData metadata = source.getMetaData(); int count = metadata.getColumnCount(); for (int i =1; i<=count; i++) { if(source.getObject(i).equals(target.getObject(i))) { return false; } } } return true; } } /END***/ /*PASTED NEW CLASS - THIS IS A JUNIT TEST CLASS*/ package a7.unittests.dao; import static org.junit.Assert.*; import java.sql.Connection; import java.sql.DriverManager; import org.junit.Test; public class TestDatabaseConnection { @Test public void testConnection() throws Exception{ UnitTestHelper helper = new UnitTestHelper(); Connection con = helper.getConnection(helper.sourceDBUrl); Connection conTarget = helper.getConnection(helper.targetDBUrl); assertTrue(con != null && conTarget != null); } } /**END***/

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  • java graphics display help

    - by java
    I know that i am not calling the graphics paint command in the mainframe in order to display it. but i'm not sure how. thanks in advance import java.awt.*; import javax.swing.*; public class MainFrame extends JFrame { private static Panel panel = new Panel(); public MainFrame() { panel.setBackground(Color.white); Container c = getContentPane(); c.add(panel); } public void paint(Graphics g) { g.drawString("abc", 20, 20); } public static void main(String[] args) { MainFrame frame = new MainFrame(); frame.setVisible(true); frame.setSize(600, 400); frame.setResizable(false); frame.setLocationRelativeTo(null); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); } }

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  • Button to add value to array and then compare result with another array on IPhone.

    - by slickplaid
    I have ten buttons that each correspond to a different number. I'm looking to record the order that these buttons are pressed and enter them into an array and then compare it to another array that is static in the app. The check should be done on the Nth button press, where N equals the number of items in the other, static array. How do I A) have a button press add a value to an array B) stop after Nth button press equal to amount of numbers in the array I'm checking against and C) compare this array to the other array?

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  • How to determine IP used by client connecting to INADDR_ANY listener socket in C

    - by codebox_rob
    I have a network server application written in C, the listener is bound using INADDR_ANY so it can accept connections via any of the IP addresses of the host on which it is installed. I need to determine which of the server's IP addresses the client used when establishing its connection - actually I just need to know whether they connected via the loopback address 127.0.0.1 or not. Partial code sample as follows (I can post the whole thing if it helps): static struct sockaddr_in serverAddress; serverAddress.sin_family = AF_INET; serverAddress.sin_addr.s_addr = INADDR_ANY; serverAddress.sin_port = htons(port); bind(listener, (struct sockaddr *) &serverAddress, sizeof(serverAddress)); listen(listener, CONNECTION_BACKLOG); SOCKET socketfd; static struct sockaddr_in clientAddress; ... socketfd = accept(listener, (struct sockaddr *) &clientAddress, &length);

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  • isAlive problem..Help to understand how it works

    - by max
    I get this error: "non-static method isAlive() cannot be referenced from a static context" what's wrong with this code..please. I'd like to detect if the thread is alive... Any help in terms of code will be highly appreciated..thanks max class RecThread extends Thread { public void run() { recFile = new File("recorded_track.wav"); // Output file type AudioFileFormat.Type fileType = null; fileType = AudioFileFormat.Type.WAVE; // if rcOn =1 thread is alive int rcOn; try { // starts recording targetDataLine.open(audioFormat); targetDataLine.start(); AudioSystem.write(new AudioInputStream(targetDataLine), fileType, recFile); if (RecThread.isAlive() == true) { rcOn =1; } else { rcOn =0; } } catch (Exception e) { showException(e); } // update actions recAction.setEnabled(true); stopRecAction.setEnabled(false); } }

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  • Is there a simpliest way of doing this?

    - by Tom Brito
    Is there a simpler way of implement this? Or a implemented method in JDK or other lib? /** * Convert a byte array to 2-byte-size hexadecimal String. */ public static String to2DigitsHex(byte[] bytes) { String hexData = ""; for (int i = 0; i < bytes.length; i++) { int intV = bytes[i] & 0xFF; // positive int String hexV = Integer.toHexString(intV); if (hexV.length() < 2) { hexV = "0" + hexV; } hexData += hexV; } return hexData; } public static void main(String[] args) { System.out.println(to2DigitsHex(new byte[] {8, 10, 12})); } the output is: "08 0C 0A" (without the spaces)

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  • LNK2005: delete already defined error in VC++

    - by user333422
    Hi, I asked this question earlier as well: http://stackoverflow.com/questions/2773168/lnk2005-delete-already-defined-error-in-vc The answer I got was that I should be using dynamic version of DLLs. I did that and it compiled fine. Now, but when I gave the exe to one of my colleagues to run, they told me - they can't run it as it requires some shared dll, so they need a static one. When I try to do static build then I get the error as mentioned in my previous link. Do, I need to provide some other file as well with exe. I have got .lib file as well in the build directory. Shall I provide taht one as well? I can run it fine on my m/c in whichever directory I put it. Any help is much appreciated as I am really stuck. Thanks in advance, Suchita

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  • Generate a Constant expression from a function

    - by Lee
    For my Google Wave robot, on the onDocumentChanged event I want to apply a filter as follows: @Capability(filter = FILTER) @Override public void onDocumentChanged(DocumentChangedEvent event) { ... } I want the filter to be generated the first time the robot is run, which I'm trying to do as follows: private static final String FILTER = generateFilter(); private static final String generateFilter(){ ... } However, it complains FILTER isn't a constant expression when used within @Capability. generateFilter() will return the same string every time it is called, I'm only using it to create the string so that when I make changes, I don't need to worry about updating the filter. Now I could be going about this all wrong, so wondered if anyone knew what I'm doing wrong, or knew a better way in which I could generate a constant expression from the function.

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  • GlGenTextures keeps returing 0's

    - by user146780
    I'm trying to generate textures like so: #define checkImageWidth 64 #define checkImageHeight 64 static GLubyte checkImage[checkImageHeight][checkImageWidth][4]; static GLubyte otherImage[checkImageHeight][checkImageWidth][4]; static GLuint texName[2]; void makeCheckImages(void) { int i, j, c; for (i = 0; i < checkImageHeight; i++) { for (j = 0; j < checkImageWidth; j++) { c = ((((i&0x8)==0)^((j&0x8))==0))*255; checkImage[i][j][0] = (GLubyte) c; checkImage[i][j][1] = (GLubyte) c; checkImage[i][j][2] = (GLubyte) c; checkImage[i][j][3] = (GLubyte) 255; c = ((((i&0x10)==0)^((j&0x10))==0))*255; otherImage[i][j][0] = (GLubyte) c; otherImage[i][j][1] = (GLubyte) 0; otherImage[i][j][2] = (GLubyte) 0; otherImage[i][j][3] = (GLubyte) 255; } } } void init(void) { glClearColor (1.0, 0.0, 0.0, 0.0); glShadeModel(GL_FLAT); glEnable(GL_DEPTH_TEST); makeCheckImages(); glPixelStorei(GL_UNPACK_ALIGNMENT, 1); glGenTextures(2, texName); glBindTexture(GL_TEXTURE_2D, texName[0]); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST); glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, checkImageWidth, checkImageHeight, 0, GL_RGBA, GL_UNSIGNED_BYTE, checkImage); glBindTexture(GL_TEXTURE_2D, texName[1]); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST); glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_DECAL); glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, checkImageWidth, checkImageHeight, 0, GL_RGBA, GL_UNSIGNED_BYTE, otherImage); glEnable(GL_TEXTURE_2D); engineGL.current.tex = texName[1]; } But when I check the values of texName[0] and [1] they are both 0, I do not understand why, what am I doing wrong. Thanks.

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  • Special simple random number generator

    - by psihodelia
    How to create a function, which on every call generates a random integer number? This number must be most random as possible (according to uniform distribution). It is only allowed to use one static variable and at most 3 elementary steps, where each step consists of only one basic arithmetic operation of arity 1 or 2. Example: int myrandom(void){ static int x; x = some_step1; x = some_step2; x = some_step3; return x; } Basic arithmetic operations are +,-,%,and, not, xor, or, left shift, right shift, multiplication and division. Of course, no rand(), random() or similar staff is allowed.

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  • Sharing Code, Images and Core Data models across iPhone and Mac project

    - by Robert
    Hi, I am maintaining a fairly large mac project and an iphone client for this project. Some code as well as some images and core data models are shared between these two projects. I want to create a shared framework containing this shared components but to my surprise, frameworks like we cocoa developers known them are not supported on the iphone os. Currently I see the following options: a) Include the files in both projects (much tedious work) b) Create a static library for both projects and manually copying the images/core data models c) Create a static lib for iphone and a framework for mac Any suggestions?

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  • Parse boolean values in strings for use with Function.apply

    - by as3cmdline
    I'm using String.split to parse a command line string into an array of strings. The result is then used to call a function using the Function.apply API. If apply(null, ["17"]) is called with this function: static function test(foo:int):void { trace(foo, typeof(foo)); } it works as expected (output: 17 number). However, calling apply(null, ["false"]) or apply(null, ["0"]) with this function: static function test(foo:Boolean):void { trace(foo, typeof(foo)); } does not work (expected output: false Boolean; actual output: true Boolean). Is there a way to make it recognize "true" and "false" (or anything else) as Boolean values, just like it does with numerical strings? Ideally "true" and "false" should also remain valid string values.

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