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• C#/.NET: Separation of multipage tiff with compression "CCITT T.6" very slow

  - by Alex B

  I need to separate multiframe tiff files, and use the following method: public static Image[] GetFrames(Image sourceImage) { Guid objGuid = sourceImage.FrameDimensionsList[0]; FrameDimension objDimension = new FrameDimension(objGuid); int frameCount = sourceImage.GetFrameCount(objDimension); Image[] images = new Image[frameCount]; for (int i = 0; i < frameCount; i++) { MemoryStream ms = new MemoryStream(); sourceImage.SelectActiveFrame(objDimension, i); sourceImage.Save(ms, ImageFormat.Tiff); images[i] = Image.FromStream(ms); } return images; } It works fine, butt if the source was encoded using the CCITT T.6 compression, separating a 20-frame-file takes up to 15 seconds on my 2,5ghz CPU. Saving the images afterwards to a single file using standard compression (LZW), the separation time is under 1 second. Is there a way to speed up the process?

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• query optimization

  - by Gaurav

  I have a query of the form SELECT uid1,uid2 FROM friend WHERE uid1 IN (SELECT uid2 FROM friend WHERE uid1='.$user_id.') and uid2 IN (SELECT uid2 FROM friend WHERE uid1='.$user_id.') The problem now is that the nested query SELECT uid2 FROM friend WHERE uid1='.$user_id.' returns a very large number of ids(approx. 5000). The table structure of the friend table is uid1(int), uid2(int). This table is used to determine whether two users are linked together as friends. Any workaround? Can I write the query in a different way? Or is there some other way to solve this issue. I'm sure I am not the first person to face such a problem. Any help would be greatly appreciated.

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• WPF: Binding with title and subitems

  - by John

  I am having some issues trying to learn WPF. What I am trying to do is to bind a class that has a string and an array of strings. I would like to bind the string as the title and array as the contents of an expander, but I am having difficulties. What am I missing to make this work? Any help would be appreciated, TIA. This is the code I have thus far: XAML <Window x:Class="WpfApplication1.Window1" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" Title="Window1" Height="300" Width="300"> <Grid> <ListBox Grid.Column="0" Name="lbTopics" ItemsSource="{Binding}"> <ListBox.ItemTemplate> <DataTemplate> <Expander Header="{Binding Path=TopicName}" > <Expander.Content> <ListBox> <ListBox.ItemTemplate> <DataTemplate> <Label Content="{Binding Path=(ItemName)}" Width="120px" Height="32px" Foreground="Black" /> </DataTemplate> </ListBox.ItemTemplate> </ListBox> </Expander.Content> </Expander> </DataTemplate> </ListBox.ItemTemplate> </ListBox> </Grid> C# namespace WpfApplication1 { public partial class Window1 : Window { public Window1() { InitializeComponent(); lbTopics.DataContext = new Topics(); } } public class Topics : ObservableCollection<Topic> { public Topics() { for (int i = 0; i < 10; i++) { this.Add(new Topic(i)); } } } public class Topic { public Topic(int i) { TopicName = "Topic " + i; ItemName = new List<string>(10); for (int j = 0; j < 10; j++) { ItemName.Add(i + " - Item " + j); } } public string TopicName { get; set; } public List<string> ItemName { get; set; } } }

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• InvalidOperationException When XML Serializing Inherited Class

  - by Nick

  I am having an issue serializing a c# class to an XML file that has a base class... here is a simple example: namespace Domain { [Serializable] public class ClassA { public virtual int MyProperty { get; set; } } } namespace Derived { public class ClassA : Domain.ClassA { public override int MyProperty { get { return 1; } set { /* Do Nothing */ } } } } When I attempt to serialize an instance of Derived.ClassA, I receive the following exception: InvalidOperationException(Types 'Domain.ClassA' and 'Derived.ClassA' both use the XML type name 'ClassA', from the namespace ". Use XML attributes to specify a unique XML name and/or namespace for the type.) The problem is that I want to create a single base class that simply defines the structure of the XML file, and then allow anyone else to derive from that class to insert business rules, but that the formatting will come through from the base. Is this possible, and if so, how do I attribute the base class to allow this?

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• [Java/Android] Multidimensional array to ListView.. how?

  - by Yverman

  I have a query result set which I like to edit first and then put it to my ListView. Without editing my data first, I could use SimpleCursorAdapter like that: ListAdapter adapter = new SimpleCursorAdapter( this, R.layout.list_item, mCursor, new String[] { "address", "city" }, new int[] { R.id.address, R.id.zip_city }); this.setListAdapter(adapter); But now, I put everything in a multidimensional array like that: if(mCursor.isFirst()) { //create a new array String[][] listData = new String[mCursor.getCount()][3]; int i = 0; do { listData[i] = new String[] { mCursor.getString(mCursor.getColumnIndex("address")), mCursor.getString(mCursor.getColumnIndex("zip")) + " " + mCursor.getString(mCursor.getColumnIndex("city")), calculateDistance(Double.parseDouble(mCursor.getString(mCursor.getColumnIndex("diff")))) }; i++; } while(mCursor.moveToNext()); } So my problem is now, I have no idea how to put this to my ListView. Could someone help me here? Sorry for my bad english and Java knowledge. :)

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• Constructor or Explicit cast

  - by Felan

  In working with Linq to Sql I create a seperate class to ferry data to a web page. To simplify creating these ferry objects I either use a specialized constructor or an explicit conversion operator. I have two questions. First which approach is better from a readibility perspective? Second while the clr code that is generated appeared to be the same to me, are there situations where one would be treated different than the other by the compiler (in lambda's or such). Example code (DatabaseFoo uses specialized constructor and BusinessFoo uses explicit operator): public class DatabaseFoo { private static int idCounter; // just to help with generating data public int Id { get; set; } public string Name { get; set; } public DatabaseFoo() { Id = idCounter++; Name = string.Format("Test{0}", Id); } public DatabaseFoo(BusinessFoo foo) { this.Id = foo.Id; this.Name = foo.Name; } } public class BusinessFoo { public int Id { get; set; } public string Name { get; set; } public static explicit operator BusinessFoo(DatabaseFoo foo) { return FromDatabaseFoo(foo); } public static BusinessFoo FromDatabaseFoo(DatabaseFoo foo) { return new BusinessFoo {Id = foo.Id, Name = foo.Name}; } } public class Program { static void Main(string[] args) { Console.WriteLine("Creating the initial list of DatabaseFoo"); IEnumerable<DatabaseFoo> dafoos = new List<DatabaseFoo>() { new DatabaseFoo(), new DatabaseFoo(), new DatabaseFoo(), new DatabaseFoo(), new DatabaseFoo(), new DatabaseFoo()}; foreach(DatabaseFoo dafoo in dafoos) Console.WriteLine(string.Format("{0}\t{1}", dafoo.Id, dafoo.Name)); Console.WriteLine("Casting the list of DatabaseFoo to a list of BusinessFoo"); IEnumerable<BusinessFoo> bufoos = from x in dafoos select (BusinessFoo) x; foreach (BusinessFoo bufoo in bufoos) Console.WriteLine(string.Format("{0}\t{1}", bufoo.Id, bufoo.Name)); Console.WriteLine("Creating a new list of DatabaseFoo by calling the constructor taking BusinessFoo"); IEnumerable<DatabaseFoo> fufoos = from x in bufoos select new DatabaseFoo(x); foreach(DatabaseFoo fufoo in fufoos) Console.WriteLine(string.Format("{0}\t{1}", fufoo.Id, fufoo.Name)); } }

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• [Hibernate Mapping] relationship set between table and mapping table to use joins.

  - by Matthew De'Loughry

  Hi guys, I have two table a "Module" table and a "StaffModule" I'm wanting to display a list of modules by which staff are present on the staffmodule mapping table. I've tried from Module join Staffmodule sm with ID = sm.MID with no luck, I get the following error Path Expected for join! however I thought I had the correct join too allow this but obviously not can any one help StaffModule HBM <?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd"> <!-- Generated Apr 26, 2010 9:50:23 AM by Hibernate Tools 3.2.1.GA --> <hibernate-mapping> <class name="Hibernate.Staffmodule" schema="WALK" table="STAFFMODULE"> <composite-id class="Hibernate.StaffmoduleId" name="id"> <key-many-to-one name="mid" class="Hibernate.Module"> <column name="MID"/> </key-many-to-one> <key-property name="staffid" type="int"> <column name="STAFFID"/> </key-property> </composite-id> </class> </hibernate-mapping> and Module.HBM <?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd"> <!-- Generated Apr 26, 2010 9:50:23 AM by Hibernate Tools 3.2.1.GA --> <hibernate-mapping> <class name="Hibernate.Module" schema="WALK" table="MODULE"> <id name="id" type="int"> <column name="ID"/> <generator class="assigned"/> </id> <property name="modulename" type="string"> <column length="50" name="MODULENAME"/> </property> <property name="teacherid" type="int"> <column name="TEACHERID" not-null="true"/> </property> </class> hope thats enough information! and thanks in advance.

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• Method hiding with interfaces

  - by fearofawhackplanet

  interface IFoo { int MyReadOnlyVar { get; } } class Foo : IFoo { int MyReadOnlyVar { get; set; } } public IFoo GetFoo() { return new Foo { MyReadOnlyVar = 1 }; } Is the above an acceptable way of implementing a readonly/immutable object? The immutability of IFoo can be broken with a temporary cast to Foo. In general (non-critical) cases, is hiding functionality through interfaces a common pattern? Or is it considered lazy coding? Or even an anti-pattern?

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• Why am I not getting the expected results with fread() in C?

  - by mauvehead

  Here is my code: #include <stdio.h> int main(void) { FILE *fp; unsigned int i; char bytes[512]; fp = fopen("myFile","r"); for(i = 0;i <= 512;i++) { fread(&bytes, sizeof(bytes), 1, fp); printf("bytes[%d]: %x\n", i, bytes[i]); } } Here is the expected output $ hexdump myFile 0000000 aa55 aa55 0060 0000 0a17 0000 b1a5 a2ea 0000010 0000 0000 614c 7563 616e 0000 0000 0000 0000020 0000 0000 0a68 0000 1001 421e 0000 0000 0000030 f6a0 487d ffff ffff 0040 0000 002f 0000 But here is what I see from my program bytes[0]: 55 bytes[1]: 8 bytes[2]: ffffffc8 bytes[3]: ffffffdd bytes[4]: 22 bytes[5]: ffffffc8 bytes[6]: ffffff91 bytes[7]: 63 bytes[8]: ffffff82 My obvious guess is that I'm either addressing something incorrectly and receiving the wrong data back or I am printing it incorrectly and viewing it the wrong way.

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• NSData release is not reclaiming memory

  - by ctpenrose

  iPhoneOS 3.2 I use NSKeyedUnarchiver's unarchiveObjectWithFile: to load a custom object that contains a single large NSData and another much smaller object. The dealloc method in my custom object gets called, the NSData object is released, its retainCount == 1 just before. Physical memory does not decrement by any amount, let alone a fraction of the NSData size, and with repetition memory warnings are reliably generated: I have test until I actually received level 2 warnings. =( NSString *archivePath = [[[NSBundle mainBundle] pathForResource:@"lingering"] ofType:@"data"] retain]; lingeringDataContainer = [[NSKeyedUnarchiver unarchiveObjectWithFile:archivePath] retain]; [archivePath release]; [lingeringDataContainer release]; and now the dealloc.... - (void) dealloc { [releasingObject release]; [lingeringData release]; [super dealloc]; } Before release: (gdb) p (int) [(NSData *) lingeringData retainCount] $1 = 1 After: (gdb) p (int) [(NSData *) lingeringData retainCount] Target does not respond to this message selector.

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• Help me understand this C code

  - by Benjamin

  INT GetTree (HWND hWnd, HTREEITEM hItem, HKEY *pRoot, TCHAR *pszKey, INT nMax) { TV_ITEM tvi; TCHAR szName[256]; HTREEITEM hParent; HWND hwndTV = GetDlgItem (hWnd, ID_TREEV); memset (&tvi, 0, sizeof (tvi)); hParent = TreeView_GetParent (hwndTV, hItem); if (hParent) { // Get the parent of the parent of the... GetTree (hWnd, hParent, pRoot, pszKey, nMax); // Get the name of the item. tvi.mask = TVIF_TEXT; tvi.hItem = hItem; tvi.pszText = szName; tvi.cchTextMax = dim(szName); TreeView_GetItem (hwndTV, &tvi); //send the TVM_GETITEM message? lstrcat (pszKey, TEXT ("\\")); lstrcat (pszKey, szName); } else { *pszKey = TEXT ('\0'); szName[0] = TEXT ('\0'); // Get the name of the item. tvi.mask = TVIF_TEXT | TVIF_PARAM; tvi.hItem = hItem; tvi.pszText = szName; tvi.cchTextMax = dim(szName); if (TreeView_GetItem (hwndTV, &tvi)) //*pRoot = (HTREEITEM)tvi.lParam; //original hItem = (HTREEITEM)tvi.lParam; else { INT rc = GetLastError(); } } return 0; } The block of code that begins with the comment "Get the name of the item" does not make sense to me. If you are getting the listview item why does the code set the parameters of the item being retrieved? If you already had the values there would be no need to retrieve them. Secondly near the comment "original" is the original line of code which will compile with a warning under embedded visual c++ 4.0, but if you copy the exact same code into visual studio 2008 it will not compile. Since I did not write any of this code, and am trying to learn, is it possible the original author made a mistake on this line? The *pRoot should point to HKEY type yet he is casting to an HTREEITEM type which should never work since the data types don't match?

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• referencing ints from other classes

  - by user357032

  if i wanted to reference an int from another class how would i go about doing that??? public class Zoom extends View { private Drawable image; public int zoomControler=20; public Zoom(Context context) { super(context); image=context.getResources().getDrawable(R.drawable.icon); setFocusable(true); } @Override protected void onDraw(Canvas canvas) { // TODO Auto-generated method stub super.onDraw(canvas); image.setBounds((getWidth()/2)-zoomControler, (getHeight()/2)-zoomControler, (getWidth()/2)+zoomControler, (getHeight()/2)+zoomControler); image.draw(canvas); } } class HelloOnTouchListener implements OnTouchListener{ @Override public boolean onTouch(View arg0, MotionEvent arg1) { return true; } } in this case i want to reference the zoomControler from the first class in the second helloontouchlistener class

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• MySQL - getting SUM of MAX results from 2 tables

  - by SODA

  Hi, Here's my problem: I have 2 identical tables (past month data, current month data) - data_2010_03, data_2010_04: Content_type (VARCHAR), content_id (INT), month_count (INT), pubDate (DATETIME) Data in month_count is updated hourly, so for each combination of content_type and content_id we insert new row, where value of month_count is incrementally updated. Now I try something like this: SELECT MAX(t1.month_count) AS max_1, MAX(t2.month_count) AS max_2, SUM(max_1 + max_2) AS result, t1.content_type, t1.content_id FROM data_2010_03 AS t1 JOIN data_2010_04 AS t2 ON t1.content_type = t2.content_type AND t1.content_id = t2.content_id WHERE t2.pubDate < '2010-04-08' AND t1.content_type = 'video' GROUP BY t1.content_id ORDER BY result desc, max_1 desc, max_2 desc LIMIT 0,10 I get an error "Unknown column 'max_1' in 'field list'. Please help.

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• What does the '&' operator do in C++?

  - by rascher

  n00b question. I am a C guy and I'm trying to understand some C++ code. I have the following function declaration: int foo(const string &myname) { cout << "called foo for: " << myname << endl; return 0; } How does the function signature differ from the equivalent C: int foo(const char *myname) Is there a difference between using string *myname vs string &myname? What is the difference between & in C++ and * in C to indicate pointers? Similarly: const string &GetMethodName() { ... } What is the & doing here? Is there some website that explains how & is used differently in C vs C++?

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• Retreive value from model into view ib MVC 3

  - by prerna

  public class HomeController : Controller { public ActionResult Index() { return View(); } /* public string Browse() { return "Hello from Browse"; public string Details(int id) { string message = "Store.Details, ID = " + id; return message; // return "Hello from Details"; }*/ public ActionResult Details(int id) { var album = new Album { Title = "Album " + id }; return View(album); } } I am new to MVC 3 ,My View is Details.aspx without Razor engine. <html> <head runat="server"> <title>Details</title> </head> <body> <div> </div> </body> </html> Can anyone help

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• Establishing a tcp connection from within a DLL

  - by Nicholas Hollander

  I'm trying to write a piece of code that will allow me to establish a TCP connection from within a DLL file. Here's my situation: I have a ruby application that needs to be able to send and receive data over a socket, but I can not access the native ruby socket methods because of the environment in which it will be running. I can however access a DLL file and run the functions within that, so I figured I would create a wrapper for winsock. Unfortunately, attempting to take a piece of code that should connect to a TCP socket in a normal C++ application throws a slew of LNK2019 errors that I can not for the life of me resolve. This is the method I'm using to connect: //Socket variable SOCKET s; //Establishes a connection to the server int server_connect(char* addr, int port) { //Start up Winsock WSADATA wsadata; int error = WSAStartup(0x0202, &wsadata); //Check if something happened if (error) return -1; //Verify Winock version if (wsadata.wVersion != 0x0202) { //Clean up and close WSACleanup(); return -2; } //Get the information needed to finalize a socket SOCKADDR_IN target; target.sin_family = AF_INET; //Address family internet target.sin_port = _WINSOCKAPI_::htons(port); //Port # target.sin_addr.s_addr = inet_addr(addr); //Create the socket s = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP); if (s == INVALID_SOCKET) { return -3; } //Try connecting if (connect(s, (SOCKADDR *)&target, sizeof(target)) == SOCKET_ERROR) { //Failed to connect return -4; } else { //Success return 1; } } The exact errors that I'm receiving are: Error 1 error LNK2019: unresolved external symbol _closesocket@4 referenced in function _server_disconnect [Project Path] Error 2 error LNK2019: unresolved external symbol _connect@12 referenced in function _server_connect [Project Path] Error 3 error LNK2019: unresolved external symbol _htons@4 referenced in function _server_connect [Project Path] Error 4 error LNK2019: unresolved external symbol _inet_addr@4 referenced in function _server_connect [Project Path] Error 5 error LNK2019: unresolved external symbol _socket@12 referenced in function _server_connect [Project Path] Error 6 error LNK2019: unresolved external symbol _WSAStartup@8 referenced in function _server_connect [Project Path] Error 7 error LNK2019: unresolved external symbol _WSACleanup@0 referenced in function _server_connect [Project Path] Error 8 error LNK1120: 7 unresolved externals [Project Path] 1 1 Many thanks!

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• argv[1] loadImage problem xcode 3.2 and snow leopard

  - by ignacionieto

  Hi Im on mac snow leopard and test these code on xcode3.2 of the Learning OpenCV everything works fine but the image doesnt appear and in the windows. I had try to understand searching for two days what does argv[1] means, but Im still no clear. Im a newbie en C++. I had the image in the same directory where the main.cpp is #include <OpenCV/cv.h> #include <OpenCV/highgui.h> int main(int argc, char** argv) { IplImage* interest_img; CvRect interest_rect; if( argc == 7 && ((interest_img= cvLoadImage( argv[1],1) ) != 0 )) { A more easy example is here: http://books.google.cl/books?id=seAgiOfu2EIC&pg=PA17&lpg=PA17&dq=cvLoadImage%28argv[1]&source=bl&ots=hRJ5bhkAOf&sig=gyYAqZBnS6lCCXJz9Fz7vzOsF-U&hl=es&ei=dvdvS-fWG8eWtgePy_WCBg&sa=X&oi=book_result&ct=result&resnum=6&ved=0CBwQ6AEwBTgK#v=onepage&q=cvLoadImage%28argv[1]&f=false both I have test it but they dont work. Please help me

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• How to get the running of time of my program with gettimeofday()

  - by Mechko

  So I get the time at the beginning of the code, run it, and then get the time. struct timeval begin, end; gettimeofday(&begin, NULL); //code to time gettimeofday(&end, NULL); //get the total number of ms that the code took: unsigned int t = end.tv_usec - begin.tv_usec; Now I want to print it out in the form "**code took 0.007 seconds to run" or something similar. So two problems: 1) t seems to contain a value of the order 6000, and I KNOW the code didn't take 6 seconds to run. 2) How can I convert t to a double, given that it's an unsigned int? Or is there an easier way to print the output the way I wanted to?

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• How to get distinct values from a column with all its corresponding values in another column

  - by Vishnu

  I know the question is bit confusing. Please read below. I have a table table_categories (id INT(11), cname VARCHAR(25),survey_id INT(11)) I want to retrieve the values for the column cname without duplication, that is distinct values but with all the values in the other column. id cname survey_id -- -------- --------- 1 Trader 2 2 Beginner 2 25 Human 1 26 Human 2 From the above example I want to retrieve distinct cnames with all the values of the survey_id. I don't want to use any programming language. Is there any way by using a single query. Please give me a solution in MySQL.

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• LINQ DefaultIfEmpty(), generating inferred argument error

  - by Refracted Paladin

  I am trying to get the below linq query to return -1 if there isn't any current value. I was looking at this article on MSDN, here, and it seemed that DefaultIfEmpty() was what I wanted. Unfortunately, I am getting a The type arguments cannot be inferred from the usage. Try specifying the type arguments explicitly. error. I guess I am not sure what that means or what it is telling me to do. Can someone explain, please. public static int CheckForDRIID(int personID) { using (var context = ConnectDataContext.Create()) { var masterIndex = (from applicationAssociation in context.tblApplicationAssociations where applicationAssociation.ApplicationID == 1 && applicationAssociation.PersonID == personID select applicationAssociation.PersonApplicationID).DefaultIfEmpty(-1).Single(); return Convert.ToInt32(masterIndex); } }

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• Core Animation performance on iphone

  - by nico

  I'm trying to do some animations using Core Animation on the iphone. I'm using CABasicAnimation on CALayer. It's a straight forward animation from a random place at the top of the screen to the bottom of the screen at random speed, I have 30 elements that doing the same animation continuously until another action happens. But the performance on the iPhone 3G is very sluggish when the animations start. The image is only 8k. Is this the right approach? How should I change so it performs better. // image cached somewhere else. CGImageRef imageRef = [[UIImage imageWithContentsOfFile:[[NSBundle mainBundle] pathForResource:name ofType:@"png"]] CGImage]; - (void)animate:(NSTimer *)timer { int startX = round(radom() % 320); float speed = 1 / round(random() % 100 + 2); CALayer *layer = [CALayer layer]; layer.name = @"layer"; layer.contents = imageRef; // cached image layer.frame = CGRectMake(0, 0, CGImageGetWidth(imageRef), CGImageGetHeight(imageRef)); int width = layer.frame.size.width; int height = layer.frame.size.height; layer.frame = CGRectMake(startX, self.view.frame.origin.y, width, height); [effectLayer addSublayer:layer]; CGPoint start = CGPointMake(startX, 0); CGPoint end = CGPointMake(startX, self.view.frame.size.height); float repeatCount = 1e100; CABasicAnimation *animation = [CABasicAnimation animationWithKeyPath:@"position"]; animation.delegate = self; animation.fromValue = [NSValue valueWithCGPoint:start]; animation.toValue = [NSValue valueWithCGPoint:end]; animation.duration = speed; animation.repeatCount = repeatCount; animation.autoreverses = NO; animation.removedOnCompletion = YES; animation.fillMode = kCAFillModeForwards; [layer addAnimation:animation forKey:@"position"]; } The animations are fired off using a NSTimer. animationTimer = [NSTimer timerWithTimeInterval:0.2 target:self selector:@selector(animate:) userInfo:nil repeats:YES]; [[NSRunLoop currentRunLoop] addTimer:animationTimer forMode:NSDefaultRunLoopMode];

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• pthread and recursively calling execvp in C

  - by eduke

  To begin I'm sorry for my english :) I looking for a way to create a thread each time my program finds a directory, in order to call the program itself but with a new argv[2] argument (which is the current dir). I did it successfully with fork() but with pthread I've some difficulties. I don't know if I can do something like that : #include <unistd.h> #include <stdlib.h> #include <stdio.h> #include <string.h> #include <sys/types.h> #include <sys/stat.h> #include <sys/wait.h> #include <dirent.h> int main(int argc, char **argv) { pthread_t threadID[10] = {0}; DIR * dir; struct dirent * entry; struct stat status; pthread_attr_t attr; pthread_attr_init(&attr); int i = 0; char *res; char *tmp; char *file; if(argc != 3) { printf("Usage : %s <file> <dir>\n", argv[0]); exit(EXIT_FAILURE); } if(stat(argv[2],&status) == 0) { dir = opendir(argv[2]); file = argv[1]; } else exit(EXIT_FAILURE); while ((entry = readdir(dir))) { if (strcmp(entry->d_name, ".") && strcmp(entry->d_name, "..")) { tmp = malloc(strlen(argv[2]) + strlen(entry->d_name) + 2); strcpy(tmp, argv[2]); strcat(tmp, "/"); strcat(tmp, entry->d_name); stat(tmp, &status); if (S_ISDIR(status.st_mode)) { argv[2] = tmp; pthread_create( &threadID[i], &attr, execvp(argv[0], argv), NULL); printf("New thread created : %d", i); i++; } else if (!strcmp(entry->d_name, file)) { printf(" %s was found - Thread number = %d\n",tmp, i); break; } free(tmp); } } pthread_join( threadID[i] , &res ); exit(EXIT_SUCCESS); } Actually it doesn't works : pthread_create( &threadID[i], &attr, execvp(argv[0], argv), NULL); I have no runtime error, but when the file to find is in another directory, the thread is not created and so execvp(argv[0], argv) is not called... Thank you for you help, Simon

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• std::map default value for build-in type

  - by Qifa Zhao

  Recently, I was confused by the std::map operator[] function. In the MSDN library, it says: "If the argument key value is not found, then it is inserted along with the default value of the data type." I tryed to search much more exactly explanation for this issue. For example here: std::map default value In this page, Michael Anderson said that "the default value is constructed by the default constructor(zero parameter constructor)". Now my quest comes to this:"what the default value for the build-in type?". Was it compiler related? Or is there a standard for this issue by the c++ stardard committee? I did a test on visual studio 2008 for the "int" type, and found the "int" type is construted with the value 0.

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• Array subscript is not an integer

  - by Dimitri

  Hello folks, following this previous question Malloc Memory Corruption in C, now i have another problem. I have the same code. Now I am trying to multiply the values contained in the arrays A * vc and store in res. Then A is set to zero and i do a second multiplication with res and vc and i store the values in A. (A and Q are square matrices and mc and vc are N lines two columns matrices or arrays). Here is my code : int jacobi_gpu(double A[], double Q[], double tol, long int dim){ int nrot, p, q, k, tid; double c, s; double *mc, *vc, *res; int i,kc; double vc1, vc2; mc = (double *)malloc(2 * dim * sizeof(double)); vc = (double *)malloc(2 * dim * sizeof(double)); vc = (double *)malloc(dim * dim * sizeof(double)); if( mc == NULL || vc == NULL){ fprintf(stderr, "pb allocation matricre\n"); exit(1); } nrot = 0; for(k = 0; k < dim - 1; k++){ eye(mc, dim); eye(vc, dim); for(tid = 0; tid < floor(dim /2); tid++){ p = (tid + k)%(dim - 1); if(tid != 0) q = (dim - tid + k - 1)%(dim - 1); else q = dim - 1; printf("p = %d | q = %d\n", p, q); if(fabs(A[p + q*dim]) > tol){ nrot++; symschur2(A, dim, p, q, &c, &s); mc[2*tid] = p; vc[2 * tid] = c; mc[2*tid + 1] = q; vc[2*tid + 1] = -s; mc[2*tid + 2*(dim - 2*tid) - 2] = p; vc[2*tid + 2*(dim - 2*tid) - 2 ] = s; mc[2*tid + 2*(dim - 2*tid) - 1] = q; vc[2 * tid + 2*(dim - 2*tid) - 1 ] = c; } } for( i = 0; i< dim; i++){ for(kc=0; kc < dim; kc++){ if( kc < floor(dim/2)) { vc1 = vc[2*kc + i*dim]; vc2 = vc[2*kc + 2*(dim - 2*kc) - 2]; }else { vc1 = vc[2*kc+1 + i*dim]; vc2 = vc[2*kc - 2*(dim - 2*kc) - 1]; } res[kc + i*dim] = A[mc[2*kc] + i*dim]*vc1 + A[mc[2*kc + 1] + i*dim]*vc2; } } zero(A, dim); for( i = 0; i< dim; i++){ for(kc=0; kc < dim; k++){ if( k < floor(dim/2)){ vc1 = vc[2*kc + i*dim]; vc2 = vc[2*kc + 2*(dim - 2*kc) - 2]; }else { vc1 = vc[2*kc+1 + i*dim]; vc2 = vc[2*kc - 2*(dim - 2*kc) - 1]; } A[kc + i*dim] = res[mc[2*kc] + i*dim]*vc1 + res[mc[2*kc + 1] + i*dim]*vc2; } } affiche(mc,dim,2,"Matrice creuse"); affiche(vc,dim,2,"Valeur creuse"); } free(mc); free(vc); free(res); return nrot; } When i try to compile, i have this error : jacobi_gpu.c: In function ‘jacobi_gpu’: jacobi_gpu.c:103: error: array subscript is not an integer jacobi_gpu.c:103: error: array subscript is not an integer jacobi_gpu.c:118: error: array subscript is not an integer jacobi_gpu.c:118: error: array subscript is not an integer make: *** [jacobi_gpu.o] Erreur 1 The corresponding lines are where I store the results in res and A : res[kc + i*dim] = A[mc[2*kc] + i*dim]*vc1 + A[mc[2*kc + 1] + i*dim]*vc2; and A[kc + i*dim] = res[mc[2*kc] + i*dim]*vc1 + res[mc[2*kc + 1] + i*dim]*vc2; Can someone explain me what is this error and how can i correct it? Thanks for your help. ;)

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• Python Beginner: Selective Printing in loops

  - by Jonathan Straus

  Hi there. I'm a very new python user (had only a little prior experience with html/javascript as far as programming goes), and was trying to find some ways to output only intermittent numbers in my loop for a basic bicycle racing simulation (10,000 lines of biker positions would be pretty excessive :P). I tried in this loop several 'reasonable' ways to communicate a condition where a floating point number equals its integer floor (int, floor division) to print out every 100 iterations or so: for i in range (0,10000): i = i + 1 t = t + t_step #t is initialized at 0 while t_step is set at .01 acceleration_rider1 = (power_rider1 / (70 * velocity_rider1)) - (force_drag1 / 70) velocity_rider1 = velocity_rider1 + (acceleration_rider1 * t_step) position_rider1 = position_rider1 + (velocity_rider1 * t_step) force_drag1 = area_rider1 * (velocity_rider1 ** 2) acceleration_rider2 = (power_rider2 / (70 * velocity_rider1)) - (force_drag2 / 70) velocity_rider2 = velocity_rider2 + (acceleration_rider2 * t_step) position_rider2 = position_rider2 + (velocity_rider2 * t_step) force_drag2 = area_rider1 * (velocity_rider2 ** 2) if t == int(t): #TRIED t == t // 1 AND OTHER VARIANTS THAT DON'T WORK HERE:( print t, "biker 1", position_rider1, "m", "\t", "biker 2", position_rider2, "m"

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