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• Bitmap manipulation in C++ on Windows

  - by Oliver

  Hi, I have myself a handle to a bitmap, in C++, on Windows: HBITMAP hBitmap; On this image I want to do some Image Recognition, pattern analysis, that sort of thing. In my studies at University, I have done this in Matlab, it is quite easy to get at the individual pixels based on their position, but I have no idea how to do this in C++ under Windows - I haven't really been able to understand what I have read so far. I have seen some references to a nice looking Bitmap class that lets you setPixel() and getPixel() and that sort of thing, but I think this is with .net . How should I go about turning my HBITMAP into something I can play with easily? I need to be able to get at the RGBA information. Are there libraries that allow me to work with the data without having to learn about DCs and BitBlt and that sort of thing?

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• Difficulty porting raw PCM output code from Java to Android AudioTrack API.

  - by IndigoParadox

  I'm attempting to port an application that plays chiptunes (NSF, SPC, etc) music files from Java SE to Android. The Android API seems to lack the javax multimedia classes that this application uses to output raw PCM audio. The closest analog I've found in the API is AudioTrack and so I've been wrestling with that. However, when I try to run one of my sample music files through my port-in-progress, all I get back is static. My suspicion is that it's the AudioTrack I've setup which is at fault. I've tried various different constructors but it all just outputs static in the end. The DataLine setup in the original code is something like: AudioFormat audioFormat = new AudioFormat( AudioFormat.Encoding.PCM_SIGNED, 44100, 16, 2, 4, 44100, true ); DataLine.Info lineInfo = new DataLine.Info( SourceDataLine.class, audioFormat ); DataLine line = (SourceDataLine)AudioSystem.getLine( lineInfo ); The constructor I'm using right now is: AudioTrack = new AudioTrack( AudioManager.STREAM_MUSIC, 44100, AudioFormat.CHANNEL_CONFIGURATION_STEREO, AudioFormat.ENCODING_PCM_16BIT, AudioTrack.getMinBufferSize( 44100, AudioFormat.CHANNEL_CONFIGURATION_STEREO, AudioFormat.ENCODING_PCM_16BIT ), AudioTrack.MODE_STREAM ); I've replaced constants and variables in those so they make sense as concisely as possible, but my basic question is if there are any obvious problems in the assumptions I made when going from one format to the other.

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• How to get around DnsRecordListFree error in .NET Framework 4.0?

  - by Greg Finzer

  I am doing an MxRecordLookup. I am getting an error when calling the DnsRecordListFree in the .NET Framework 4.0. I am using Windows 7. How do I get around it? Here is the error: System.MethodAccessException: Attempt by security transparent method to call native code through method. Here is my code: [DllImport("dnsapi", EntryPoint = "DnsQuery_W", CharSet = CharSet.Unicode, SetLastError = true, ExactSpelling = true)] private static extern int DnsQuery([MarshalAs(UnmanagedType.VBByRefStr)]ref string pszName, QueryTypes wType, QueryOptions options, int aipServers, ref IntPtr ppQueryResults, int pReserved); [DllImport("dnsapi", CharSet = CharSet.Auto, SetLastError = true)] private static extern void DnsRecordListFree(IntPtr pRecordList, int FreeType); public List<string> GetMXRecords(string domain) { List<string> records = new List<string>(); IntPtr ptr1 = IntPtr.Zero; IntPtr ptr2 = IntPtr.Zero; MXRecord recMx; try { int result = DnsQuery(ref domain, QueryTypes.DNS_TYPE_MX, QueryOptions.DNS_QUERY_BYPASS_CACHE, 0, ref ptr1, 0); if (result != 0) { if (result == 9003) { //No Record Exists } else { //Some other error } } for (ptr2 = ptr1; !ptr2.Equals(IntPtr.Zero); ptr2 = recMx.pNext) { recMx = (MXRecord)Marshal.PtrToStructure(ptr2, typeof(MXRecord)); if (recMx.wType == 15) { records.Add(Marshal.PtrToStringAuto(recMx.pNameExchange)); } } } finally { DnsRecordListFree(ptr1, 0); } return records; }

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• What exactly is a reentrant function?

  - by eSKay

  Most of the times, the definition of reentrance is quoted from Wikipedia: A computer program or routine is described as reentrant if it can be safely called again before its previous invocation has been completed (i.e it can be safely executed concurrently). To be reentrant, a computer program or routine: Must hold no static (or global) non-constant data. Must not return the address to static (or global) non-constant data. Must work only on the data provided to it by the caller. Must not rely on locks to singleton resources. Must not modify its own code (unless executing in its own unique thread storage) Must not call non-reentrant computer programs or routines. How is safely defined? If a program can be safely executed concurrently, does it always mean that it is reentrant? What exactly is the common thread between the six points mentioned that I should keep in mind while checking my code for reentrant capabilities? Also, Are all recursive functions reentrant? Are all thread-safe functions reentrant? Are all recursive and thread-safe functions reentrant? While writing this question, one thing comes to mind: Are the terms like reentrance and thread safety absolute at all i.e. do they have fixed concrete definations? For, if they are not, this question is not very meaningful. Thanks!

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• Extend and Overload MS and Point Types

  - by dr d b karron

  Do I have make my own Point and Vector types to overload them ? Why does this not work ? namespace System . windows { public partial struct Point : IFormattable { public static Point operator * ( Point P , double D ) { Point Po = new Point ( ); return Po; } } } namespace SilverlightApplication36 { public partial class MainPage : UserControl { public static void ShrinkingRectangle ( WriteableBitmap wBM , int x1 , int y1 , int x2 , int y2 , Color C ) { wBM . DrawRectangle ( x1 , y1 , x2 , y2 , Colors . Red ); Point Center = Mean ( x1 , y1 , x2 , y2 ); wBM . SetPixel ( Center , Colors.Blue , 3 ); Point P1 = new Point ( x1 , y1 ); Point P2 = new Point ( x1 , y2 ); Point P3 = new Point ( x1 , y2 ); Point P4 = new Point ( x2 , y1 ); const int Steps = 10; for ( int i = 0 ; i < Steps ; i++ ) { double iF = (double)(i+1) / (double)Steps; double jF = ( 1.0 - iF ); Point P11 = **P1 * jF;** } }

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• XNA or C# Pop-up progress bar for the LoadContent() method

  - by Warlax

  Hey people, We wrote a small game using Microsoft's XNA Game Studio 3.1. The LoadContent() takes a long time because, other than loading models, and config files, we're also running some one-time (per run) terrain analysis. We are not C# or XNA programmers... we're Java programmers, and want to be able to give the user some feedback that the system is loading. Preferably, this will be through a simple pop-up with a progress bar that will say something simple like "loading please wait". The progress bar doesn't have to be a 0 to 1 progress bar, it can instead be one of those 'back and forth' progress bars. I was hoping for some quick copy-paste ready code to just do that - as it is not a central piece of our project, nor do we have a need to delve into too much documentation. I appreciate you time, effort, and possible donation. Thanks.

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• Leak caused by fread

  - by Jack

  I'm profiling code of a game I wrote and I'm wondering how it is possible that the following snippet causes an heap increase of 4kb (I'm profiling with Heapshot Analysis of Xcode) every time it is executed: u8 WorldManager::versionOfMap(FILE *file) { char magic[4]; u8 version; fread(magic, 4, 1, file); <-- this is the line fread(&version,1,1,file); fseek(file, 0, SEEK_SET); return version; } According to the profiler the highlighted line allocates 4.00Kb of memory with a malloc every time the function is called, memory which is never released. This thing seems to happen with other calls to fread around the code, but this was the most eclatant one. Is there anything trivial I'm missing? Is it something internal I shouldn't care about? Just as a note: I'm profiling it on an iPhone and it's compiled as release (-O2).

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• PDO using singleton stored as class properity

  - by Misiur

  Hi again. OOP drives me crazy. I can't move PDO to work. Here's my DB class: class DB extends PDO { public function &instance($dsn, $username = null, $password = null, $driver_options = array()) { static $instance = null; if($instance === null) { try { $instance = new self($dsn, $username, $password, $driver_options); } catch(PDOException $e) { throw new DBException($e->getMessage()); } } return $instance; } } It's okay when i do something like this: try { $db = new DB(DB_TYPE.':host='.DB_HOST.';dbname='.DB_NAME, DB_USER, DB_PASS); } catch(DBException $e) { echo $e->getMessage(); } But this: try { $db = DB::instance(DB_TYPE.':host='.DB_HOST.';dbname='.DB_NAME, DB_USER, DB_PASS); } catch(DBException $e) { echo $e->getMessage(); } Does nothing. I mean, even when I use wrong password/username, I don't get any exception. Second thing - I have class which is "heart" of my site: class Core { static private $instance; public $db; public function __construct() { if(!self::$instance) { $this->db = DB::instance(DB_TYPE.':hpost='.DB_HOST.';dbname='.DB_NAME, DB_USER, DB_PASS); } return self::$instance; } private function __clone() { } } I've tried to use "new DB" inside class, but this: $r = $core->db->query("SELECT * FROM me_config"); print_r($r->fetch()); Return nothing. $sql = "SELECT * FROM me_config"; print_r($core->db->query($sql)); I get: PDOStatement Object ( [queryString] => SELECT * FROM me_config ) I'm really confused, what am I doing wrong?

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• colorbox not displaying first caption from flickr gallery integration

  - by Mark

  I am pulling small thumbnails into my page from the flickr API, and using Colorbox to display larger thumbnails and captions from the title attribute. Using the API with C#. However, on the first instance of opening colorbox it does not display the caption from the anchors title attribute. If you click next or previous then it appears. The actual caption is physically there in the source code, just not getting put into the colorbox window. Demo here, if you click on a thumbnail you will see there is no caption, click next then prev and it will appear. Here's the code: <script type="text/javascript"> $(function() { $("a[rel='group']").colorbox({ opacity: 0.75 }); }); </script> <a href='http://farm6.static.flickr.com/5015/5511378425_e63d4a62f7.jpg' title='Little Hermit (Peter Dunn)' rel='group' class='tooltip'> <img src='http://farm6.static.flickr.com/5015/5511378425_e63d4a62f7_s.jpg' alt='Little Hermit (Peter Dunn)' /> </a> If i view source, the title attribute is populated with the caption, but if i ook in firebug it is not in the colorbox code. Any help on this would be great Ive ran out of ideas!

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• Qt application crashing immediately without debugging info. How do I track down the problem?

  - by jjacksonRIAB

  I run an Qt app I've built: ./App Segmentation fault I run it with strace: strace ./App execve("./App", ["./App"], [/* 27 vars */]) = 0 --- SIGSEGV (Segmentation fault) @ 0 (0) --- +++ killed by SIGSEGV +++ Process 868 detached Again, no useful info. I run it with gdb: (gdb) run Starting program: /root/test/App Reading symbols from shared object read from target memory...(no debugging symbols found)...done. Loaded system supplied DSO at 0xffffe000 Program received signal SIGSEGV, Segmentation fault. 0x00000001 in ?? () Again, nothing. I run it with valgrind: ==948== Process terminating with default action of signal 11 (SIGSEGV) ==948== Bad permissions for mapped region at address 0x0 ==948== at 0x1: (within /root/test/App) Even if I put in debugging symbols, it doesn't give any more useful info. ldd shows all libraries being linked properly. Is there any other way I can find out what's wrong? I can't even do standard printf, cout, etc debugging. The executable doesn't even seem to start running at all. I rebuilt with symbols, and tried the suggestion below (gdb) break main Breakpoint 1 at 0x45470 (gdb) run Starting program: /root/test/App Breakpoint 1 at 0x80045470 Reading symbols from shared object read from target memory...done. Loaded system supplied DSO at 0xffffe000 Program received signal SIGSEGV, Segmentation fault. 0x00000001 in ?? () I checked for static initializers and I don't seem to have any. Yep, I tried printf, cout, etc. It doesn't even make it into the main routine, so I'm looking for problems with static initializers in link libraries, adding them in one-by-one. I'm not getting any stack traces either.

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• User defined literal arguments are not constexpr?

  - by Pubby

  I'm testing out user defined literals. I want to make _fac return the factorial of the number. Having it call a constexpr function works, however it doesn't let me do it with templates as the compiler complains that the arguments are not and cannot be constexpr. I'm confused by this - aren't literals constant expressions? The 5 in 5_fac is always a literal that can be evaluated during compile time, so why can't I use it as such? First method: constexpr int factorial_function(int x) { return (x > 0) ? x * factorial_function(x - 1) : 1; } constexpr int operator "" _fac(unsigned long long x) { return factorial_function(x); // this works } Second method: template <int N> struct factorial { static const unsigned int value = N * factorial<N - 1>::value; }; template <> struct factorial<0> { static const unsigned int value = 1; }; constexpr int operator "" _fac(unsigned long long x) { return factorial_template<x>::value; // doesn't work - x is not a constexpr }

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• Android shared library which is not JNI based

  - by Mondain

  I am developing a library for Android applications which does not use native code (JNI). I have tried suppling the library as an external jar in my Android projects but this method does not include the library contents in the apk and thus throws class not found errors when run in the emulator or device. I have also tried creating the library as an Android project in itself and this does work, but only for public static properties (not methods). With the library and application both being in separate apk's I can see that the VM notices references to the library and can read some properties, but when an attempt to instantiate a class in the library is executed I get class not found even though I can read the public static properties from it (very frustrating!!). I realize that Davlik byte code is not the same as Java byte code but I am having trouble even finding good information about how to solve what would seem to be a very simple issue in Android. I am looking into the old PlatformLibrary stuff right now but I am not convinced this will work either since the sample has been removed from the Android site :( So help me out if you can, if I find the answer before this happens I will share it. viva la Android!

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• PHP OOP singleton doesn't return object

  - by Misiur

  Weird trouble. I've used singleton multiple times but this particular case just doesn't want to work. Dump says that instance is null. define('ROOT', "/"); define('INC', 'includes/'); define('CLS', 'classes/'); require_once(CLS.'Core/Core.class.php'); $core = Core::getInstance(); var_dump($core->instance); $core->settings(INC.'config.php'); $core->go(); Core class class Core { static $instance; public $db; public $created = false; private function __construct() { $this->created = true; } static function getInstance() { if(!self::$instance) { self::$instance = new Core(); } else { return self::$instance; } } public function settings($path = null) { ... } public function go() { ... } } Error code Fatal error: Call to a member function settings() on a non-object in path It's possibly some stupid typo, but I don't have any errors in my editor. Thanks for the fast responses as always.

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• Java source code generation frameworks

  - by Superfilin

  I have a set of Java 5 source files with old-style Doclet tags, comments and annotations. And based on that I would like to write a generator for another set of Java classes. What is the best way to do that? And are there any good standalone libraries for code analysis/generation in Java? Any shared exprience in this field is appreciated. So, far I have found these: JaxME's Java Source Reflection - seems good, but it does not seem to support annotations. Also it had no release since 2006. Annogen - uses JDK's Doclet generator, which has some bugs under 1.5 JDK. Also it had no releases for a long time. Javaparser - seems good as well and pretty recent, but only supports Visitor pattern for a single class i.e. no query mechanism like in the 2 above packages.

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• How can I pass in a params of Expression<Func<T, object>> to a method?

  - by Pure.Krome

  Hi folks, I have the following two methods :- public static IQueryable<T> IncludeAssociations<T>(this IQueryable<T> source, params string[] associations) { ... } public static IQueryable<T> IncludeAssociations<T>(this IQueryable<T> source, params Expression<Func<T, object>>[] expressions) { ... } Now, when I try and pass in a params of Expression<Func<T, object>>[], it always calls the first method (the string[]' and of course, that value isNULL`) Eg. Expression<Func<Order, object>> x1 = x => x.User; Expression<Func<Order, object>> x2 = x => x.User.Passport; var foo = _orderRepo .Find() .IncludeAssociations(new {x1, x2} ) .ToList(); Can anyone see what I've done wrong? Why is it thinking my params are a string? Can I force the type, of the 2x variables?

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• Applying the Decorator Pattern to Forms

  - by devoured elysium

  I am trying to apply the Decorator Design Pattern to the following situation: I have 3 different kind of forms: Green, Yellow, Red. Now, each of those forms can have different set of attributes. They can have a minimize box disabled, a maximized box disabled and they can be always on top. I tried to model this the following way: Form <---------------------------------------FormDecorator /\ /\ |---------|-----------| |----------------------|-----------------| GreenForm YellowForm RedForm MinimizeButtonDisabled MaximizedButtonDisabled AlwaysOnTop Here is my GreenForm code: public class GreenForm : Form { public GreenForm() { this.BackColor = Color.GreenYellow; } public override sealed Color BackColor { get { return base.BackColor; } set { base.BackColor = value; } } } FormDecorator: public abstract class FormDecorator : Form { private Form _decoratorForm; protected FormDecorator(Form decoratorForm) { this._decoratorForm = decoratorForm; } } and finally NoMaximizeDecorator: public class NoMaximizeDecorator : FormDecorator { public NoMaximizeDecorator(Form decoratorForm) : base(decoratorForm) { this.MaximizeBox = false; } } So here is the running code: static void Main() { Application.EnableVisualStyles(); Application.SetCompatibleTextRenderingDefault(false); Application.Run(CreateForm()); } static Form CreateForm() { Form form = new GreenForm(); form = new NoMaximizeDecorator(form); form = new NoMinimizeDecorator(form); return form; } The problem is that I get a form that isn't green and that still allows me to maximize it. It is only taking in consideration the NoMinimizeDecorator form. I do comprehend why this happens but I'm having trouble understanding how to make this work with this Pattern. I know probably there are better ways of achieving what I want. I made this example as an attempt to apply the Decorator Pattern to something. Maybe this wasn't the best pattern I could have used(if one, at all) to this kind of scenario. Is there any other pattern more suitable than the Decorator to accomplish this? Am I doing something wrong when trying to implement the Decorator Pattern? Thanks

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• What was that tutorial on pointers?

  - by pecker

  Hello, I once read a tutorial/article on Pointers somewhere. It was not a general tutorial but it explained how to clearly understand the complex & confusing pointers (especially like the ones that are usually asked in interview). It was more like http://www.codeweblog.com/right-left-rule-complex-pointer-analysis/ I'm unable to find it. Could any one post it here. PS: I did tried to google it but couldn't find. I'm asking it here because I thought it was popular.

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• Can this extension method be improved?

  - by Newbie

  I have the following extension method public static class ListExtensions { public static IEnumerable<T> Search<T>(this ICollection<T> collection, string stringToSearch) { foreach (T t in collection) { Type k = t.GetType(); PropertyInfo pi = k.GetProperty("Name"); if (pi.GetValue(t, null).Equals(stringToSearch)) { yield return t; } } } } What it does is by using reflection, it finds the name property and then filteres the record from the collection based on the matching string. This method is being called as List<FactorClass> listFC = new List<FactorClass>(); listFC.Add(new FactorClass { Name = "BKP", FactorValue="Book to price",IsGlobal =false }); listFC.Add(new FactorClass { Name = "YLD", FactorValue = "Dividend yield", IsGlobal = false }); listFC.Add(new FactorClass { Name = "EPM", FactorValue = "emp", IsGlobal = false }); listFC.Add(new FactorClass { Name = "SE", FactorValue = "something else", IsGlobal = false }); List<FactorClass> listFC1 = listFC.Search("BKP").ToList(); It is working fine. But a closer look into the extension method will reveal that Type k = t.GetType(); PropertyInfo pi = k.GetProperty("Name"); is actually inside a foreach loop which is actually not needed. I think we can take it outside the loop. But how? PLease help. (C#3.0)

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• Are these two functions the same?

  - by Ranhiru

  There is a function in the AES algorithm, to multiply a byte by 2 in Galois Field. This is the function given in a website private static byte gfmultby02(byte b) { if (b < 0x80) return (byte)(int)(b <<1); else return (byte)( (int)(b << 1) ^ (int)(0x1b) ); } This is the function i wrote. private static byte MulGF2(byte x) { if (x < 0x80) return (byte)(x << 1); else { return (byte)((x << 1) ^ 0x1b); } } What i need to know is, given any byte whether this will perform in the same manner. Actually I am worried about the extra conversion of to int and then again to byte. So far I have tested and it looks fine. Does the extra cast to int and then to byte make a difference?

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• When does the call() method get called in a Java Executor using Callable objects?

  - by MalcomTucker

  This is some sample code from an example. What I need to know is when call() gets called on the callable? What triggers it? public class CallableExample { public static class WordLengthCallable implements Callable { private String word; public WordLengthCallable(String word) { this.word = word; } public Integer call() { return Integer.valueOf(word.length()); } } public static void main(String args[]) throws Exception { ExecutorService pool = Executors.newFixedThreadPool(3); Set<Future<Integer>> set = new HashSet<Future<Integer>>(); for (String word: args) { Callable<Integer> callable = new WordLengthCallable(word); Future<Integer> future = pool.submit(callable); //**DOES THIS CALL call()?** set.add(future); } int sum = 0; for (Future<Integer> future : set) { sum += future.get();//**OR DOES THIS CALL call()?** } System.out.printf("The sum of lengths is %s%n", sum); System.exit(sum); } }

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• Do I really ned bindParam?

  - by sandelius

  Hi there! I'm trying to do a little PDO CRUD to learn some PDO. I have a question about bindParam. Here's my update method right now: public static function update($conditions = array(), $data = array(), $table = '') { self::instance(); // Late static bindings (PHP 5.3) $table = ($table === '') ? self::table() : $table; // Check which data array we want to use $values = (empty($data)) ? self::$_fields : $data; $sql = "UPDATE $table SET "; foreach ($values as $f => $v) { $sql .= "$f = ?, "; } // let's build the conditions self::build_conditions($conditions); // fix our WHERE, AND, OR, LIKE conditions $extra = self::$condition_string; // querystring $sql = rtrim($sql, ', ') . $extra; // let's merge the arrays into on $v_val = array_values($values); $c_val = array_values($conditions); $array = array_merge($v_val, self::$condition_array); $stmt = self::$db->prepare($sql); return $stmt->execute($array); } in my "self::$condition_array" I get all the right values from the ?. SO the query looks like this: UPDATE table SET this = ?, another = ? WHERE title = ? AND time = ? as you can see I dont use bindParams instead I pass the right values in the right order ($array) directly into the execute($array) method. This works like a charm BUT is it safe not use use bindParam here? If not then how can I do it? Thanks from Sweden Tobias

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• How can I get the type I want?

  - by Danny Chen

  There are a lot of such classes in my project (very old and stable code, I can't do many changes to them, maybe slight changes are OK) public class MyEntity { public long ID { get; set; } public string Name { get; set; } public decimal Salary { get; set; } public static GetMyEntity ( long ID ) { MyEntity e = new MyEntity(); // load data from DB and bind to this instance return e; } } For some reasons, now I need to do this: Type t = Type.GetType("XXX"); // XXX is one of the above classes' name MethodInfo staticM= t.GetMethods(BindingFlags.Public | BindingFlags.Static).FirstOrDefault();// I'm sure I can get the correct one var o = staticM.Invoke(...); //returns a object, but I want the type above! If I pass "MyEntity" at beginning, I hope I can get o as MyEntity! Please NOTE that I know the "name of the class" only. MyEntity e = staticM.Invoke(...) as MyEntity; can't be used here.

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• Most Elegant Way to write isPrime in java

  - by Anantha Kumaran

  public class Prime { public static boolean isPrime1(int n) { if (n <= 1) { return false; } if (n == 2) { return true; } for (int i = 2; i <= Math.sqrt(n) + 1; i++) { if (n % i == 0) { return false; } } return true; } public static boolean isPrime2(int n) { if (n <= 1) { return false; } if (n == 2) { return true; } if (n % 2 == 0) { return false; } for (int i = 3; i <= Math.sqrt(n) + 1; i = i + 2) { if (n % i == 0) { return false; } } return true; } } public class PrimeTest { public PrimeTest() { } @Test public void testIsPrime() throws IllegalArgumentException, IllegalAccessException, InvocationTargetException { Prime prime = new Prime(); TreeMap<Long, String> methodMap = new TreeMap<Long, String>(); for (Method method : Prime.class.getDeclaredMethods()) { long startTime = System.currentTimeMillis(); int primeCount = 0; for (int i = 0; i < 1000000; i++) { if ((Boolean) method.invoke(prime, i)) { primeCount++; } } long endTime = System.currentTimeMillis(); Assert.assertEquals(method.getName() + " failed ", 78498, primeCount); methodMap.put(endTime - startTime, method.getName()); } for (Entry<Long, String> entry : methodMap.entrySet()) { System.out.println(entry.getValue() + " " + entry.getKey() + " Milli seconds "); } } } I am trying to find the fastest way to check whether the given number is prime or not. This is what is finally came up with. Is there any better way than the second implementation(isPrime2).

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• Why is this linq extension method hit the database twice?

  - by Pure.Krome

  Hi folks, I have an extension method called ToListIfNotNullOrEmpty(), which is hitting the DB twice, instead of once. The first time it returns one result, the second time it returns all the correct results. I'm pretty sure the first time it hits the database, is when the .Any() method is getting called. here's the code. public static IList<T> ToListIfNotNullOrEmpty<T>(this IEnumerable<T> value) { if (value.IsNullOrEmpty()) { return null; } if (value is IList<T>) { return (value as IList<T>); } return new List<T>(value); } public static bool IsNullOrEmpty<T>(this IEnumerable<T> value) { if (value != null) { return !value.Any(); } return true; } I'm hoping to refactor it so that, before the .Any() method is called, it actually enumerates through the entire list. If i do the following, only one DB call is made, because the list is already enumerated. var pewPew = (from x in whatever select x) .ToList() // This enumerates. .ToListIsNotNullOrEmpty(); // This checks the enumerated result. I sorta don't really want to call ToList() then my extension method. Any ideas, folks?

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• What is the most useful R trick?

  - by Dirk Eddelbuettel

  In order to share some more tips and tricks for R, what is you single-most useful feature or trick? Clever vectorization? Data input/output? Visualization and graphics? Statistical analysis? Special functions? The interactive environment itself? One item per post, and we will see if we get a winner by means of votes. [Edit 25-Aug 2008]: So after one week, it seems that the simple str() won the poll. As I like to recommend that one myself, it is an easy answer to accept.

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