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• What sorting algorithm is this?

  - by Mike

  Hi, I have a sorting algorithm as follows. My question is, which sorting algorithm is this? I thought it was bubble sort, but it does not do multiple runs. Any idea? Thanks! //sorting in descending order struct node { int value; node* NEXT; } //Assume HEAD pointer denotes the first element in the //linked list // only change the values…don’t have to change the //pointers Sort( Node *Head) { node* first,second,temp; first= Head; while(first!=null) { second=first->NEXT; while(second!=null) { if(first->value < second->value) { temp = new node(); temp->value=first->value; first->value=second->value; second->value=temp->value; delete temp; } second=second->NEXT; } first=first->NEXT; } }

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• realloc() & ARC

  - by RynoB

  How would I be able to rewrite the the following utility class to get all the class string values for a specific type - using the objective-c runtime functions as shown below? The ARC documentation specifically states that realloc should be avoided and I also get the following compiler error on this this line: classList = realloc(classList, sizeof(Class) * numClasses); "Implicit conversion of a non-Objective-C pointer type 'void *' to '__unsafe_unretained Class *' is disallowed with ARC" The the below code is a reference to the original article which can be found here. + (NSArray *)classStringsForClassesOfType:(Class)filterType { int numClasses = 0, newNumClasses = objc_getClassList(NULL, 0); Class *classList = NULL; while (numClasses < newNumClasses) { numClasses = newNumClasses; classList = realloc(classList, sizeof(Class) * numClasses); newNumClasses = objc_getClassList(classList, numClasses); } NSMutableArray *classesArray = [NSMutableArray array]; for (int i = 0; i < numClasses; i++) { Class superClass = classList[i]; do { superClass = class_getSuperclass(superClass); if (superClass == filterType) { [classesArray addObject:NSStringFromClass(classList[i])]; break; } } while (superClass); } free(classList); return classesArray; } Your help will be much appreciated. Thanks

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• android bindservice

  - by mnish

  hi, I get null pointer exception at line mService.start() when i try to bind to an already started service. I do the same thing from different activity(where the service gets started) everythig goes right. All these activities are part of one application. What do you think I do wrong? public class RouteOnMap extends MapActivity{ private static final int NEW_LOCATION = 1; private static final int GPS_OFF = 2; private MapView mMapView; private ILocService mService; private boolean mServiceStarted; private boolean mBound; private Intent mServiceIntent; private double mLatitude, mLongitude; private ServiceConnection connection = new ServiceConnection() { public void onServiceConnected(ComponentName className, IBinder iservice) { mService = ILocService.Stub.asInterface(iservice); mBound = true; } public void onServiceDisconnected(ComponentName className) { mService = null; mBound = false; } }; public void onCreate(Bundle savedInstanceState){ super.onCreate(savedInstanceState); setContentView(R.layout.mapview); mMapView = (MapView) findViewById(R.id.mapview); mMapView.setBuiltInZoomControls(true); mServiceIntent = new Intent(); mLatitude = 0.0; mLongitude = 0.0; mBound = false; } @Override public void onStart(){ super.onStart(); mServiceIntent.setClass(this, LocationService.class); //startService(mServiceIntent); if(!mBound){ mBound = true; this.bindService(mServiceIntent, connection, Context.BIND_AUTO_CREATE); } } @Override public void onResume(){ super.onResume(); try { mService.start(); } catch (RemoteException e) { e.printStackTrace(); } } @Override public void onPause(){ super.onPause(); if(mBound){ this.unbindService(connection); } } @Override protected boolean isRouteDisplayed() { // TODO Auto-generated method stub return false; } }

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• AST with fixed nodes instead of error nodes in antlr

  - by ahe

  I have an antlr generated Java parser that uses the C target and it works quite well. The problem is I also want it to parse erroneous code and produce a meaningful AST. If I feed it a minimal Java class with one import after which a semicolon is missing it produces two "Tree Error Node" objects where the "import" token and the tokens for the imported class should be. But since it parses the following code correctly and produces the correct nodes for this code it must recover from the error by adding the semicolon or by resyncing. Is there a way to make antlr reflect this fixed input it produces internally in the AST? Or can I at least get the tokens/text that produced the "Tree Node Errors" somehow? In the C targets antlr3commontreeadaptor.c around line 200 the following fragment indicates that the C target only creates dummy error nodes so far: static pANTLR3_BASE_TREE errorNode (pANTLR3_BASE_TREE_ADAPTOR adaptor, pANTLR3_TOKEN_STREAM ctnstream, pANTLR3_COMMON_TOKEN startToken, pANTLR3_COMMON_TOKEN stopToken, pANTLR3_EXCEPTION e) { // Use the supplied common tree node stream to get another tree from the factory // TODO: Look at creating the erronode as in Java, but this is complicated by the // need to track and free the memory allocated to it, so for now, we just // want something in the tree that isn't a NULL pointer. // return adaptor->createTypeText(adaptor, ANTLR3_TOKEN_INVALID, (pANTLR3_UINT8)"Tree Error Node"); } Am I out of luck here and only the error nodes the Java target produces would allow me to retrieve the text of the erroneous nodes?

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• Linux Kernel - Red/Black Trees

  - by CodeRanger

  I'm trying to implement a red/black tree in Linux per task_struct using code from linux/rbtree.h. I can get a red/black tree inserting properly in a standalone space in the kernel such as a module but when I try to get the same code to function with the rb_root declared in either task_struct or task_struct-files_struct, I get a SEGFAULT everytime I try an insert. Here's some code: In task_struct I create a rb_root struct for my tree (not a pointer). In init_task.h, macro INIT_TASK(tsk), I set this equal to RB_ROOT. To do an insert, I use this code: rb_insert(&(current-fd_tree), &rbnode); This is where the issue occurs. My insert command is the standard insert that is documented in all RBTree documentation for the kernel: int my_insert(struct rb_root *root, struct mytype *data) { struct rb_node **new = &(root->rb_node), *parent = NULL; /* Figure out where to put new node */ while (*new) { struct mytype *this = container_of(*new, struct mytype, node); int result = strcmp(data->keystring, this->keystring); parent = *new; if (result < 0) new = &((*new)->rb_left); else if (result > 0) new = &((*new)->rb_right); else return FALSE; } /* Add new node and rebalance tree. */ rb_link_node(&data->node, parent, new); rb_insert_color(&data->node, root); return TRUE; } Is there something I'm missing? Some reason this would work fine if I made a tree root outside of task_struct? If I make rb_root inside of a module this insert works fine. But once I put the actual tree root in the task_struct or even in the task_struct-files_struct, I get a SEGFAULT. Can a root node not be added in these structs? Any tips are greatly appreciated. I've tried nearly everything I can think of.

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• Why doesn't my cursor change to an Hourglass in my FindDialog in Delphi?

  - by lkessler

  I am simply opening my FindDialog with: FindDialog.Execute; In my FindDialog.OnFind event, I want to change the cursor to an hourglass for searches through large files, which may take a few seconds. So in the OnFind event I do this: Screen.Cursor := crHourglass; (code that searches for the text and displays it) ... Screen.Cursor := crDefault; What happens is while searching for the text, the cursor properly changes to the hourglass (or rotating circle in Vista) and then back to the pointer when the search is completed. However, this only happens on the main form. It does not happen on the FindDialog itself. The default cursor remains on the FindDialog during the search. While the search is happening if I move the cursor over the FindDialog it changes to the default, and if I move it off and over the main form it becomes the hourglass. This does not seem like what is supposed to happen. Am I doing something wrong or does something special need to be done to get the cursor to be the hourglass on all forms? For reference, I'm using Delphi 2009.

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• Use Math class to calculate

  - by LC

  Write a JAVA program that calculates the surface area of a cylinder, C= 2( p r2) + 2 p r h, where r is the radius and h is the height of the cylinder. Allow the user to enter in a radius and a height. Format the output to three decimal places. Use the constant PI and the method pow() from the Math class. This is what I've done so far but it can not run. Can anyone help me ? import Java.util Scanner; public class Ex5 { public static void main (String[] args) { Scanner input.new Scanner(System.in); double radius,height,area; System.out.print("Please enter the radius of the Cylinder"); radius = input.nextDouble(); System.out.print("Please enter the height of the Cylinder"); height = input.nextDouble(); area = (4*Math.PI*radius)+2*Math.PIMath.POW(radius,2); System.out.println("The surface of the cylinder" + area); } }

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• ASP.NET MVC 2: Mechanics behind an Order / Order Line in a edit form

  - by Dr. Zim

  In this question I am looking for links/code to handle an IList<OrderLine> in an MVC 2 edit form. Specifically I am interested in sending a complete order to the client, then posting the edited order back to an object (to persist) using: Html.EditorFor(m = m.orderlines[i]) (where orderlines is an enumerable object) Editing an Order that has multiple order lines (two tables, Order and OrderLine, one to many) is apparently difficult. Is there any links/examples/patterns out there to advise how to create this form that edits an entity and related entities in a single form (in C# MVC 2)? The IList is really throwing me for a loop. Should I have it there (while still having one form to edit one order)? How could you use the server side factory to create a blank OrderLine in the form while not posting the entire form back to the server? I am hoping we don't treat the individual order lines with individual save buttons, deletes, etc. (for example, they may open an order, delete all the lines, then click cancel, which shouldn't have altered the order itself in either the repository nor the database. Example classes: public class ViewModel { public Order order {get;set;} // Only one order } public class Order { public int ID {get;set;} // Order Identity public string name {get;set;} public IList<OrderLine> orderlines {get;set;} // Order has multiple lines } public class OrderLine { public int orderID {get;set;} // references Order ID above public int orderLineID {get;set;} // Order Line identity (need?) public Product refProduct {get;set;} // Product value object public int quantity {get;set;} // How many we want public double price {get;set;} // Current sale price }

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• Make an image transparent in IE to show non-transparent background

  - by Select0r

  Hi, I'm trying to get this thing to work in IE (any version - works in FF, Opera, Safari, Chrome ...): I have a DIV with a background-image. The DIV also contains an image that should be transparent onMouseOver. The expected behaviour now is that the DIV-background would shine through the transparent image (which it does in all browsers but IE). Instead it looks like the image is getting transparent but on a white background, I can't see the DIV's background through the image. Here's some code: <div><a href="#" class"dragItem"><img /></a></div> And some CSS: .dojoDndItemOver { cursor : pointer; filter : alpha(opacity = 50); opacity : 0.5; -moz-opacity : 0.5; -khtml-opacity : 0.5; } .dragItem:hover { filter : alpha(opacity = 30); opacity : 0.3; -moz-opacity : 0.3; -khtml-opacity : 0.3; background : none; } All of this is embedded in a Dojo Drag-n-Drop-system, so dojoDndItemOver will automatically be set to the DIV on MouseOver, dragItem is set to the href around the image (using the same class on the image directly doesn't work at all as IE doesn't support "hover" on other items that href). Any ideas? Or is it an IE-speciality to just "simulate" transparency on images by somehow just greying them out instead of providing real transparency and showing whatever is beneath?

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• Deriving an HTMLElement Object from jQuery Object

  - by Jasconius

  I'm doing a fairly exhaustive series of DOM manipulations where a few elements (specifically form elements) have some events. I am dynamically creating (actually cloning from a source element) several boxes and assigning a change() event to them. The change event executes, and within the context of the event, "this" is the HTML Element Object. What I need to do at this point however is determine a contact for this HTML Element Object. I have these objects stored already as jQuery entities in assorted arrays, but obviously [HTMLElement Object] != [Object Object] And the trick is that I cannot cast $(this) and make a valid comparison since that would create a new object and the pointer would be different. So... I've been banging my head against this for a while. In the past I've been able to circumvent this problem by doing an innerHTML comparison, but in this case the objects I am comparing are 100% identical, just there's lots of them. Therefore I need a solid comparison. This would be easy if I could somehow derive the HTMLElement object from my originating jQuery object. Thoughts, other ideas? Help. :(

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• function's return address is different from its supposed value, buffer overflow,

  - by ultrajohn

  Good day everyone! I’m trying to understand how buffer overflow works. I’m doing this for my project in a computer security course I’m taking. Right now, I’m in the process of determining the address of the function’s return address which I’m supposed to change to perform a buffer overflow attack. I’ve written a simple program based from an example I’ve read in the internet. What this program does is it creates an integer pointer that will be made to point to the address of the function return address in the stack. To do this, (granted I understand how a function/program variables get organized in the stack), I add 8 to the buffer variable’ address and set it as the value of ret. I’m not doing anything here that would change the address contained in the location of func’s return address. here's the program: Output of the program when gets excecuted: As you can see, I’m printing the address of the variables buffer and ret. I’ve added an additional statement printing the value of the ret variable (supposed location of func return address, so this should print the address of the next instruction which will get executed after func returns from execution). Here is the dump which shows the supposed address of the instruction to be executed after func returns. (Underlined in green) As you can see, that value is way different from the value printed contained in the variable ret. My question is, why are they different? (of course in the assumption that what I’ve done are all right). Else, what have I done wrong? Is my understanding of the program’s runtime stack wrong? Please, help me understand this. My project is due nextweek and I’ve barely touched it yet. I’m sorry if I’m being demanding, I badly need your help.

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• Create a Desktop Shortcut to an existing FOLDER using WiX

  - by Sach

  I have the need to create a Desktop Shortcut to an existing FOLDER (NOT to a file) using Wix. To elaborate more, my installer program has a CustomAction program written using C# associated with it. This CustomAction program creates a folder named "BSS" of which the path is selected by user. C:\ProgramData\MT\BSS Now I need to place a Desktop Shortcut to this folder using WiX. However, I encounter a problem since this folder does not have a folder structure within WiX. The closest code I could find was the following. <Directory Id="DesktopFolder" Name="Desktop"/> <Directory Id="CommonAppDataFolder" Name="ProgramDataFolder"/> <Component Id="ComponentBSStrageShortcut" Guid="{8436995c-2e76-4030-b92d-c6b4bc243c43}"> <Shortcut Id="ShortcutBSStrageShortcut" Directory="DesktopFolder" WorkingDirectory="APPLICATIONFOLDER" Target="[CommonAppDataFolder]/MTK/BSStrage" Name="BSStrage" Show="normal"/> <RegistryValue Action="write" Key="SOFTWARE/MTK/BackStreet" Root="HKCU" Type="string" KeyPath="yes" Value="ApplicationFolderName"/> </Component> When I build the installer this way, it actually creates a shortcut on Desktop. However, WiX seems to think that BSStrage is a file/application so it places a shortcut to an imaginary application called BSStrage in the location C:\ProgramData\MT. But double clicking on it dosen't help as there is no program that can be used to open it. Obviously I'm doing it wrong here. Can someone please help me with this, so as how to overcome this problem. Note that I'm extremely new to Wix (it's been only two days) and has never worked with it before. Any code sample would be of great help.

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• Troubles Iterating Over A HashMap with JSF, MyFaces & Facelets

  - by Lee Theobald

  Hi all, I'm having some trouble looping over a HashMap to print out it's values to the screen. Could someone double check my code to see what I'm doing wrong. I can't seem to find anything wrong but there must be something. In a servlet, I am adding the following to the request: Map<String, String> facetValues = new HashMap<String, String>(); // Filling the map req.setAttribute(facetField.getName(), facetValues); In one case "facetField.getName()" evaluates to "discipline". So in my page I have the following: <ui:repeat value="${requestScope.discipline}" var="item"> <li>Item: <c:out value="${item}"/>, Key: <c:out value="${item.key}"/>, Value: <c:out value="${item.item}"/></li> </ui:repeat> The loop is ran once but all the outputs are blank?!? I would have at least expected something in item if it's gone over the loop once. Checking the debug popup for Facelets, discipline is there and on the loop. Printing it to the screen results in something that looks like a map to me (I've shortened the output) : {300=0, 1600=0, 200=0, ... , 2200=0} I've also tried with a c:forEach but I'm getting the same results. So does anyone have any ideas where I'm going wrong? Thanks for any input, Lee

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• Javascript: Controlling the order that event handlers / listeners are exeucted in

  - by LRE

  Once again the IE Monster has hit me with an odd problem. I'm writing some changes into an asp.net site I inherited a while back. One of the problems is that in some pages there are several controls that add javascript functions as handlers to the onload event (using YUI if that matters). Some of those event handlers assume certain other functions have been executed. This is well and good in Firefox and IE7 as the handlers seem to execute in order of registration. IE8 on the other hand does this backwards. I could go with some kind of double-checking approach but given the controls are present in several pages I feel that'd create even more dependencies. So I've started cooking up my own queue class that I push the functions to and can control their execution order. Then I'll register an onload handler that instructs the queue to execute in my preferred order. I'm part way through that and have started wondering 2 things: Am I going OTT? Am I reinventing the wheel? Anyone have any insights? Any clean solutions that allow me to easily enforce execution order?

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• WPF DataTemplate - Overlay

  - by David Ward

  I have a class that I need to provide the datatemplate for. Currently I have two datatemplates, one for when Enabled == true and one for when Enabled == false. The datatemplate for the class is actually the one below which changes the template used based on a trigger: <DataTemplate x:Key="ActionNodeTemplateSelector"> <ContentPresenter Content="{Binding}" Name="cp" /> <DataTemplate.Triggers> <DataTrigger Binding="{Binding Enabled}" Value="True"> <Setter TargetName="cp" Property="ContentTemplate" Value="{StaticResource ActionNodeTemplate}" /> </DataTrigger> <DataTrigger Binding="{Binding Enabled}" Value="False"> <Setter TargetName="cp" Property="ContentTemplate" Value="{StaticResource ActionNodeDisabledTemplate}" /> </DataTrigger> </DataTemplate.Triggers> </DataTemplate> This all works well. However, now I want to also display an image overlay if the "Completed" property is true and a different image if it is incomplete. I could easily carry on using my approach to trigger on the Completed property as well but this would double the number of templates and feels wrong. Is there a way that I could have a trigger on my DataTemplate that will allow me to overlay the correct image over the existing template which is based on the Enabled property?

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• Windows Programming: ID2D1Bitmap Interface - Getting the Bitmap Data

  - by LostInBrackets

  I've been writing my own library of functions to access some of the new Direct2D Windows libraries. In particular, I've been working on the ID2D1Bitmap interface. I wanted to write a function to return a pointer to the start of the bitmap data (for the editing of particular pixels, or custom encoding or whatever else I might wish for in the future). Unfortunately... problem ahead... I can't seem to find a way to get access to the raw pixel data from the ID2D1Bitmap Interface. Does anyone have an idea how to access this? One of my friends suggested drawing the bitmap to a surface and extracting the bitmap data from there. I don't know if this would work. It definitely seems inefficient and I wouldn't know which kind of surface to use. Any help is appreciated. (c++ in particular, but I assume the code won't be tooo different between languages) (I know I could just read in the data direct from the file, but I'm using the WIC decoders which means it could be in any number of indecipherable formats)

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• Call dll - pcshll32.dll using delphi

  - by Davis

  Hi, I need to call hllapi function of pcshll32.dll using delphi. It's works with personal communications of ibm. How can i change the code bellow to delphi ? Thanks !!! The EHLLAPI entry point (hllapi) is always called with the following four parameters: EHLLAPI Function Number (input) Data Buffer (input/output) Buffer Length (input/output) Presentation Space Position (input); Return Code (output) The prototype for IBM Standard EHLLAPI is: [long hllapi (LPWORD, LPSTR, LPWORD, LPWORD); The prototype for IBM Enhanced EHLLAPI is: [long hllapi (LPINT, LPSTR, LPINT, LPINT); Each parameter is passed by reference not by value. Thus each parameter to the function call must be a pointer to the value, not the value itself. For example, the following is a correct example of calling the EHLLAPI Query Session Status function: #include "hapi_c.h" struct HLDQuerySessionStatus QueryData; int Func, Len, Rc; long Rc; memset(QueryData, 0, sizeof(QueryData)); // Init buffer QueryData.qsst_shortname = ©A©; // Session to query Func = HA_QUERY_SESSION_STATUS; // Function number Len = sizeof(QueryData); // Len of buffer Rc = 0; // Unused on input hllapi(&Func, (char *)&QueryData, &Len, &Rc); // Call EHLLAPI if (Rc != 0) { // Check return code // ...Error handling } All the parameters in the hllapi call are pointers and the return code of the EHLLAPI function is returned in the value of the 4th parameter, not as the value of the function.

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• ActiveX control loading but not activating correctly (only when using in Reg Free COM)

  - by embnut

  I have an ActiveX control (created using C#) that I am adding to a form in Visual FoxPro using late binding. It works without problems when I register the control. I want to use reg free COM and created necessary manifest files. Now it load and displays in an inactive state until I double click or programatically activate it. I don't think it has anything to do with the reg free com manifest files. However is there something I need to do to set it up before/after making the late binding call AddObject()? this.AddObject('OleControl1', 'oleControl', 'SomeCompany.SomeOleControl') When I check the OleTypeAllowed Property of the OleControl created by AddObject() it is 1 (Embedded OLE object) instead of -2 (ActiveX object). So the OleControl got instantiated to the wrong type. I also tried the following: DEFINE(d) a subclass of OleControl and set the property OleTypeAllowed = -2. Used late binding to load the control. It did not work as required. The OleTypeAllowed came back as 1 Registered the ActiveX control. Added the ActiveX control to the project as a subclass using the visual editor. Unregistered the control. Used late binding to load the control. It did not work as required. The OleTypeAllowed came back as 1. Is it possible to load the OleControl as a ActiveX control? Any input from VB that I can convert to FoxPro would also be appreciated.

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• STLport crash (race condition, Darwin only?)

  - by Jonas Byström

  When I run STLport on Darwin I get a strange crash. (Haven't seen it anywhere else than on Mac, but exactly same thing crash on both i686 and PowerPC.) This is what it looks like in gdb: Program received signal EXC_BAD_ACCESS, Could not access memory. Reason: 13 at address: 0x0000000000000000 [Switching to process 21097] 0x000000010120f47c in stlp_std::__node_alloc_impl::_M_allocate () It may be some setting in STLport, I noticed that Mac.h and MacOSX.h seemed far behind on features. I also know that it it must be some type of race condition, since it doesn't occur just by calling this method (implicity called). The crash happens mainly when I push the system, running 10 simultaneous threads that do a lot of string handling. Other theories I come up with have to do with compiler flags (configure script) and g++ 4.2 bugs (seems like 4.4.3 isn't on Mac yet with Objective-C support, which I need to link with). HELP!!! :) Edit: I run unit tests, which do all sorts of things. This problem arise when I start 10 threads that push the system; and it always comes down to std::string::append which eventually boils down to _M_allocate. Since I can't even get a descent dump of the code that's causing the problem, I figure I'm doing something bad. Could it be so since it's trying to execute at instruction pointer 0x000...000? Are dynlibs built as DLLs in Windows with a jump table? Could it perhaps be that such a jump table has been overwritten for some reason? That would probably explain this behavior. (The code is huge, if I run out of other ideas, I'll post a minimum crashing sample here.)

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• How does virtual inheritance solve the diamond problem?

  - by cambr

  class A { public: void eat(){ cout<<"A";} }; class B: virtual public A { public: void eat(){ cout<<"B";} }; class C: virtual public A { public: void eat(){ cout<<"C";} }; class D: public B,C { public: void eat(){ cout<<"D";} }; int main(){ A *a = new D(); a->eat(); } I understand the diamond problem, and above piece of code does not have that problem. How exatly does virtual inheritance solve the problem? What I understand: When I say A *a = new D();, the compiler wants to know if an object of type D can be assigned to a pointer of type A, but it has two paths that it can follow, but cannot decide by itself. So, how does virtual inheritance resolve the issue (help compiler take the decision)?

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• argv Memory Allocation

  - by Joshua Green

  I was wondering if someone could tell me what I am doing wrong that I get this Unhandled Exception error message: 0xC0000005: Access violation reading location 0x0000000c. with a green pointer pointing at my first Prolog code (fid_t): Here is my header file: class UserTaskProlog { public: UserTaskProlog( ArRobot* r ); ~UserTaskProlog( ); protected: int cycles; char* argv[ 1 ]; term_t tf; term_t tx; term_t goal_term; functor_t goal_functor; ArRobot* robot; void logTask( ); }; And here is my main code: UserTaskProlog::UserTaskProlog( ArRobot* r ) : robot( r ), robotTaskFunc( this, &UserTaskProlog::logTask ) { cycles = 0; argv[ 0 ] = "libpl.dll"; argv[ 1 ] = NULL; PL_initialise( 1, argv ); PlCall( "consult( 'myPrologFile.pl' )" ); robot->addSensorInterpTask( "UserTaskProlog", 50, &robotTaskFunc ); } UserTaskProlog::~UserTaskProlog( ) { robot->remSensorInterpTask( &robotTaskFunc ); } void UserTaskProlog::logTask( ) { cycles++; fid_t fid = PL_open_foreign_frame( ); tf = PL_new_term_ref( ); PL_put_integer( tf, 5 ); tx = PL_new_term_ref( ); goal_term = PL_new_term_ref( ); goal_functor = PL_new_functor( PL_new_atom( "factorial" ), 2 ); PL_cons_functor( goal_term, goal_functor, tf, tx ); int fact; if ( PL_call( goal_term, NULL ) ) { PL_get_integer( tx, &fact ); cout << fact << endl; } PL_discard_foreign_frame( fid ); } int main( int argc, char** argv ) { ArRobot robot; ArArgumentParser argParser( &argc, argv ); UserTaskProlog talk( &robot ); } Thank you,

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• Haskell Linear Algebra Matrix Library for Arbitrary Element Types

  - by Johannes Weiß

  I'm looking for a Haskell linear algebra library that has the following features: Matrix multiplication Matrix addition Matrix transposition Rank calculation Matrix inversion is a plus and has the following properties: arbitrary element (scalar) types (in particular element types that are not Storable instances). My elements are an instance of Num, additionally the multiplicative inverse can be calculated. The elements mathematically form a finite field (??2256). That should be enough to implement the features mentioned above. arbitrary matrix sizes (I'll probably need something like 100x100, but the matrix sizes will depend on the user's input so it should not be limited by anything else but the memory or the computational power available) as fast as possible, but I'm aware that a library for arbitrary elements will probably not perform like a C/Fortran library that does the work (interfaced via FFI) because of the indirection of arbitrary (non Int, Double or similar) types. At least one pointer gets dereferenced when an element is touched (written in Haskell, this is not a real requirement for me, but since my elements are no Storable instances the library has to be written in Haskell) I already tried very hard and evaluated everything that looked promising (most of the libraries on Hackage directly state that they wont work for me). In particular I wrote test code using: hmatrix, assumes Storable elements Vec, but the documentation states: Low Dimension : Although the dimensionality is limited only by what GHC will handle, the library is meant for 2,3 and 4 dimensions. For general linear algebra, check out the excellent hmatrix library and blas bindings I looked into the code and the documentation of many more libraries but nothing seems to suit my needs :-(. Update Since there seems to be nothing, I started a project on GitHub which aims to develop such a library. The current state is very minimalistic, not optimized for speed at all and only the most basic functions have tests and therefore should work. But should you be interested in using or helping out developing it: Contact me (you'll find my mail address on my web site) or send pull requests.

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• Anyone got a nifty credit expiry algorithm?

  - by garethkeenan

  Our website uses a credit system to allow users to purchase inexpensive digital goods (eg. photos). We use credits, rather than asking the user to pay for items individually, because the items are cheap and we are trying to keep our credit-card/PayPal overhead low. Because we aren't a bank, we have to expire credits after a certain amount of time. We expire deposit credits after a year, but other types of credits (bonuses, prizes, refunds) may have a different shelf-life. When a buyer buys an item, we spend the credit that is going to expire first. Our current system keeps track of every deposit by storing the original value and the remainder to be spent. We keep a list of all purchases as well, of course. I am currently moving to a system which is much more like a traditional double-entry accounting system. A deposit will create a ledger item, increasing the user's 'spending' account balance. Every purchase will also create a ledger item, decreasing the user's 'spending' account balance. The new system has running balances, while the old system does not, which greatly improves our ability to find problems and do reconciliations. We do not want to use the old system of keeping a 'remainder' value attached to each deposit record because it is inefficient to replay a user's activities to calculate what the remainder of each deposit is over time (for the user's statement). So, after all of this verbose introduction, my question is "Does anyone else out there have a similar system of expiring credits?" If you could describe how you calculate expired credits it would be a great help. If all expired credits had the exact same shelf life, we would be able to calculate the expired amount using: Total Deposits - Total Spending - Deposits Not Due To Expire = Amount to Expire However, because deposits can have different shelf lives, this formula does not work because more than one deposit can be partially spent at any given time.

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• How to change identifier quote character in SSIS for connection to ODBC DSN

  - by William Rose

  I'm trying to create an SSIS 2008 Data Source View that reads from an Ingres database via the ODBC driver for Ingres. I've downloaded the Ingres 10 Community Edition to get the ODBC driver, installed it, set up the data access server and a DSN on the server running SSIS. If I connect to the SQL Server 2008 Database Engine on the server running SSIS, I can retrieve data from Ingres over the ODBC DSN by running the following command: SELECT * FROM OPENROWSET( 'MSDASQL' , 'DSN=IngresODBC;UID=testuser;PWD=testpass' , 'SELECT * FROM iitables') So I am quite sure that the ODBC setup is correct. If I try the same query with SQL Server style bracketed identifier quotes, I get an error, as Ingres doesn't support this syntax. SELECT * FROM OPENROWSET( 'MSDASQL' , 'DSN=IngresODBC;UID=testuser;PWD=testpass' , 'SELECT * FROM [iitables]') The error is "[Ingres][Ingres 10.0 ODBC Driver][Ingres 10.0]line 1, Unexpected character '['.". What I am finding is that I get the same error when I try to add tables from Ingres to an SSIS Data Source View. The initial step of selecting the ODBC Provider works fine, and I am shown a list of tables / views to add. I then select any table, and try to add it to the view, and get "ERROR [5000A] [Ingres][Ingres 10.0 ODBC Driver][Ingres 10.0]line 3, Unexpected character '['.". Following Ed Harper's suggestion of creating a named query also seems to be stymied. If I put into my named query the following text: SELECT * FROM "iitables" I still get an error: "ERROR [5000A] [Ingres][Ingres 10.0 ODBC Driver][Ingres 10.0]line 2, Unexpected character '['". According to the error, the query text passed by SSIS to ODBC was: SELECT [iitables].* FROM ( SELECT * FROM "iitables" ) AS [iitables] It seems that SSIS assumes that bracket quote characters are acceptable, when they aren't. How can I persuade it not to use them? Double quotes are acceptable.

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• C++ CIN cin skips randomly

  - by user69514

  I have this program, but cin in randomly skips.. I mean sometimes it does, and sometimes it doesn't. Any ideas how to fix this? int main(){ /** get course name, number of students, and assignment name **/ string course_name; int numb_students; string assignment_name; Assignment* assignment; cout << "Enter the name of the course" << endl; cin >> course_name; cout << "Enter the number of students" << endl; cin >> numb_students; cout << "Enter the name of the assignment" << endl; cin >> assignment_name; assignment = new Assignment(assignment_name); /** iterate asking for student name and score **/ int i = 0; string student_name; double student_score = 0.0; while( i < numb_students ){ cout << "Enter the name for student #" << i << endl; cin >> student_name; cout << "Enter the score for student #" << i << endl; cin >> student_score; assignment->addScore( Student( student_name, student_score )); i++; } }

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