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  • identifying the type

    - by Gokul
    Hi, In my application, there is a inheritance hierarchy in which only the classes that are at the end of the inheritance chain are non-abstract classes. Also there is some usage of boost::variant. I want to write a function which takes a pointer and a Type and says whether the object belongs to that type. For example template< typename Type, bool TypeisAbstract, typename ptrType > bool checkType( ptrType* t) { return ( typeid(*t) == typeid(Type) ); } template< typename Type, typename ptrType > bool checkType<Type, true, ptrType>( ptrType* t) { return ( dynamic_cast<Type*>(t) != NULL ); } Now if there is a boost variant, i want to find out whether the boost variant stores that particular type. Can someone help me with that? Thanks, Gokul.

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  • How to get QWebKit to display image?

    - by George Edison
    Okay, I have a Qt executable in the same directory as a file logo.png. I call the following: QString msg("<html><body><img src='logo.png' /></body></html>"); webView->setHtml(msg); where webview is the QWebKit pointer However, when I execute the program, the image does not display. I am executing the program from the directory that the image is in... why won't it display?

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  • basic boost date_time input format question

    - by Chris H
    I've got a pointer to a string, (char *) as input. The date/time looks like this: Sat, 10 Apr 2010 19:30:00 I'm only interested in the date, not the time. I created an "input_facet" with the format I want: boost::date_time::date_input_facet inFmt("%a %d %b %Y"); but I'm not sure what to do with it. Ultimately I'd like to create a date object from the string. I'm pretty sure I'm on the right track with that input facet and format, but I have no idea how to use it. Thanks.

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  • Finding the closest grid coordinate to the mouse onclick with javascript/jQuery

    - by Acorn
    What I'm trying to do is make a grid of invisible coordinates on the page equally spaced. I then want a <div> to be placed at whatever grid coordinate is closest to the pointer when onclick is triggered. Here's the rough idea: I have the tracking of the mouse coordinates and the placing of the <div> worked out fine. What I'm stuck with is how to approach the problem of the grid of coordinates. First of all, should I have all my coordinates in an array which I then compare my onclick coordinate to? Or seeing as my grid coordinates follow a rule, could I do something like finding out which coordinate that is a multiple of whatever my spacing is is closest to the onclick coordinate? And then, where do I start with working out which grid point coordinate is closest? What's the best way of going about it? Thanks!

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  • using R to estimate finite mixture model with underlying Markov process

    - by stevejb
    Hello, My apologies if this is more of a statistics question than an R question. I am trying to estimate the following model in R. y_t = mu0 (1 - S_t) + mu1 S_t + e_t e_t ~ N(0, sigma_t^2) sigma_t^2 = sigma_0^2 (1 - S_t) + sigma_1^2 S_t where mu_t = mu0 if S_t = 0, mu_t = mu1 if S_t = 1, and S_t is a Markov process, either 0 or 1, with transition probabilities P(S_t = 1 | S_t-1 = 1 ) = p and P(S_t = 0 | S_t-1 = 0 ) = q. Would 'flexmix' be a good library to use for this? I am new to this kind of statistics so any pointer to the right library would be appreciated. Thanks,

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  • Unregistering a COM wrapped .NET assembly

    - by flopdix
    I created a COM exposed .NET 2.0 dll and registered with my windows operating system using 'regasm' and 'gacutil' (in GAC). Then I tried to call this component from my classic ASP page. It worked fine. But, I need to change the functionality of my assembly. I unregistered it again using 'regasm' and 'gacutil' (from GAC) utilities and copied my new .NET DLL and registered again (This time using a new version of the DLL). For some reason, i still have a pointer to my old assembly and new calls to the DLL from ASP page are not working. Any Ideas on what process i need to follow to ensure that all the references to the old version are completely removed? I appreciate any help.

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  • C -Segmentation fault !

    - by FILIaS
    It seems at least weird to me... The program runs normally.But after I call the enter() function for the 4th time,there is a segmentation fault!I would appreciate any help. With the following function enter() I wanna add user commands' datas to a list. [Some part of the code is already posted on another question of me, but I think I should post it again...as it's a different problem I'm facing now.] /* struct for all the datas that user enters on file*/ typedef struct catalog { char short_name[50]; char surname[50]; signed int amount; char description[1000]; struct catalog *next; }catalog,*catalogPointer; catalogPointer current; catalogPointer head = NULL; void enter(void) //user command: i <name> <surname> <amount> <description> { int n,j=2,k=0; char temp[1500]; char *short_name,*surname,*description; signed int amount; char* params = strchr(command,' ') + 1; //strchr returns a pointer to the 1st space on the command.U want a pointer to the char right after that space. strcpy(temp, params); //params is saved as temp. char *curToken = strtok(temp," "); //strtok cuts 'temp' into strings between the spaces and saves them to 'curToken' printf("temp is:%s \n",temp); printf("\nWhat you entered for saving:\n"); for (n = 0; curToken; ++n) //until curToken ends: { if (curToken) { short_name = malloc(strlen(curToken) + 1); strncpy(short_name, curToken, sizeof (short_name)); } printf("Short Name: %s \n",short_name); curToken = strtok(NULL," "); if (curToken) { surname = malloc(strlen(curToken) + 1); strncpy(surname, curToken,sizeof (surname)); } printf("SurName: %s \n",surname); curToken = strtok(NULL," "); if (curToken) { //int * amount= malloc(sizeof (signed int *)); char *chk; amount = (int) strtol(curToken, &chk, 10); if (!isspace(*chk) && *chk != 0) fprintf(stderr,"Warning: expected integer value for amount, received %s instead\n",curToken); } printf("Amount: %d \n",amount); curToken = strtok(NULL,"\0"); if (curToken) { description = malloc(strlen(curToken) + 1); strncpy(description, curToken, sizeof (description)); } printf("Description: %s \n",description); break; } if (findEntryExists(head, surname,short_name) != NULL) //call function in order to see if entry exists already on the catalog printf("\nAn entry for <%s %s> is already in the catalog!\nNew entry not entered.\n",short_name,surname); else { printf("\nTry to entry <%s %s %d %s> in the catalog list!\n",short_name,surname,amount,description); newEntry(&head,short_name,surname,amount,description); printf("\n**Entry done!**\n"); } // Maintain the list in alphabetical order by surname. } catalogPointer findEntryExists (catalogPointer head, char num[],char first[]) { catalogPointer p = head; while (p != NULL && strcmp(p->surname, num) != 0 && strcmp(p->short_name,first) != 0) { p = p->next; } return p; } catalogPointer newEntry (catalog** headRef,char short_name[], char surname[], signed int amount, char description[]) { catalogPointer newNode = (catalogPointer)malloc(sizeof(catalog)); catalogPointer first; catalogPointer second; catalogPointer tmp; first=head; second=NULL; strcpy(newNode->short_name, short_name); strcpy(newNode->surname, surname); newNode->amount=amount; strcpy(newNode->description, description); while (first!=NULL) { if (strcmp(surname,first->surname)>0) second=first; else if (strcmp(surname,first->surname)==0) { if (strcmp(short_name,first->short_name)>0) second=first; } first=first->next; } if (second==NULL) { newNode->next=head; head=newNode; } else //SEGMENTATION APPEARS WHEN IT GETS HERE! { tmp=second->next; newNode->next=tmp; first->next=newNode; } } UPDATE: SegFault appears only when it gets on the 'else' loop of InsertSort() function. I observed that segmentation fault appears when i try to put on the list names that are after it. For example, if in the list exists: [Name:b Surname:b Amount:6 Description:b] [Name:c Surname:c Amount:5 Description:c] [Name:d Surname:d Amount:4 Description:d] [Name:e Surname:e Amount:3 Description:e] [Name:g Surname:g Amount:2 Description:g] [Name:x Surname:x Amount:1 Description:x] and i put: " x z 77 gege" there is a segmentation but if i put "x a 77 gege" it continues normally....

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  • Strange IE7 behaviors(or not)

    - by c0mrade
    I see no reason why this shouldn't work in all browsers, here is my css for anchor tag : .myButton{ background:none repeat scroll 0 0 #FFFFFF; border:1px solid #D8DFEA !important; color:#3B5998; cursor:pointer; font-size:20px; padding:10px; } Here is how it looks in IE7 : And here is how it looks in other browsers : HTML is nothing unusual as well : <a href="#" class="myButton">Beta</a> All of this is inside table, this anchor html is wrapped around with : <tr> <td><a>...</a></td> <tr> I don't think this has to do it with anything but I mentioned it just in case, so the button is missing border top, any indications what might cause this?

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  • variable names in function definition, call and declaration

    - by yCalleecharan
    Hi, I see C books that use the same variable names in the function definition, calling function and declaration. Others use the same variable names in the calling function and in the declaration/prototype but a different one in the definition as in: void blabla(int something); //prototype blabla(something) // calling function inside main after something has been initialized to int void blabla(int something_else) //definition I have two questions: What convention is best to use in C?; Does the convention apply regardless whether a value is being passed "by-value" or if it's being passed by a pointer? Thanks a lot...

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  • Is it possible to call a user-space callback function from kernel space in Linux (ioctl)?

    - by Makis
    Is it possible to expand the ioctl interface in Linux so that the user-space application can send a pointer to a function to the kernel space driver? I'm in particular thinking of ways to handle the stream in user-controllable way but doing it in the kernel. Those operations could be attached to the kernel module but this would make development a lot easier as I wouldn't need to mess with the kernel during development. More specifically, this would be the process: Data is read by the driver to a buffer. Data is handled by these user-defined functions in place. Some more handling is done, possibly with some HW blocks. Data is used by a user-space application.

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  • How to dynamically replace a method implementation in ObjC2?

    - by Abhi
    I am trying to learn how to write plugins using SIMBL. I got my plugin to load with the target application, and also know the method that I wish to override. However, I am not able to use class_getInstanceMethod correctly based on snippets on the Internet. Have things changed in OSX 10.6 and/or ObjC2? The following code from culater.net gives "Dereferencing pointer to incomplete type" on the second-last statement: BOOL DTRenameSelector(Class _class, SEL _oldSelector, SEL _newSelector) { Method method = nil; // First, look for the methods method = class_getInstanceMethod(_class, _oldSelector); if (method == nil) return NO; method->method_name = _newSelector; return YES; } Is there a complete example of how to override a method using SIMBL plugins? Thanks!

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  • Hide select option Cross Browser

    - by Tapas Bose
    Isn't there any way to do it? I have made jsFiddle which is not working in IE. The piece of code is given below: The HTML <select id="testing"> <option value="1">Option 1</option> <option value="2">Option 2</option> <option value="3">Option 3</option> </select> The jQuery $(document).ready(function() { $('select#testing option').eq(1).attr({ disabled: 'disabled' }); }); The CSS select option[disabled] {display: none;} Any pointer would be helpful. Note: I cannot use .remove() method.

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  • Does the WCF framework support the XSD IDREF restriction?

    - by Gerard
    A nice feature in XSD is the IDREF restriction, e.g.: <xs:restriction base="xs:IDREF"> <xs:pattern value="[0-9a-zA-Z\-]+"/> </xs:restriction> I used this restriction with great benefit in a Java JAXWS-project. An object serialized in a SOAP XML datamodel can hold a reference (pointer) to another object in the same SOAP message. I want to try the same approach in a C# WCF-project, can it be done? On the web site Data Contract Schema Reference I can see e.g. Id ignored, Ref forbidden, but I am not sure whether I understand what that means.

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  • Navigating cursor rows in SQLite

    - by Alan Harris-Reid
    Hi there, I am trying to understand how the following builtin functions work when sequentially processing cursor rows. The descriptions come from the Python 3.1 manual (using SQLite3) Cursor.fetchone() Fetches the next row of a query result set, returning a single sequence. Cursor.fetchmany() Fetches the next set of rows of a query result, returning a list. Cursor.fetchall() Fetches all (remaining) rows of a query result, returning a list. So if I have a loop in which I am processing one row at a time using cursor.fetchone(), and some later code requires that I return to the first row, or fetch all rows using fetchall(), how do I do it? The concept is a bit strange to me, especially coming from a Foxpro background which has the concept of a record pointer which can be moved to the 1st or last row in a cursor (go top/bottom), or go to the nth row (go n) Any help would be appreciated. Alan

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  • FIFO implementation

    - by Narek
    While implementing a FIFO I have used the following structure: struct Node { T info_; Node* link_; Node(T info, Node* link=0): info_(info), link_(link) {} }; I think this a well known trick for lots of STL containers (for example for List). Is this a good practice? What it means for compiler when you say that Node has a member with a type of it's pointer? Is this a kind of infinite loop? And finally, if this is a bad practice, how I could implement a better FIFO. EDIT: People, this is all about implemenation. I am enough familiar with STL library, and know a plenty of containers from several libraries. Just I want to discuss with people who can gave a good implementation or a good advice.

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  • Server returned HTTP response code: 500 for URL

    - by user617162
    java.io.IOException: Server returned HTTP response code: 500 for URL: http://ww .huadt.com.cn/zh-cn/i/l/@357671030745308@V500@0000@AUTOLOW@1@11d590f7$GPRMC,065 48.000,A,3959.8587,N,11617.2447,E,0.00,55.32,210311,,,A*56@@ at sun.net.www.protocol.http.HttpURLConnection.getInputStream(Unknown S urce) at hdt.SendCmdToP.Sendplatform(SendCmdToP.java:67) at hdt.SendCmdToP.process(SendCmdToP.java:198) at hdt.SendCmdToP.run(SendCmdToP.java:131) java.lang.NullPointerException at hdt.SendCmdToP.Sendplatform(SendCmdToP.java:91) at hdt.SendCmdToP.process(SendCmdToP.java:198) at hdt.SendCmdToP.run(SendCmdToP.java:131) Appeared pointer, and 500 wrong with the closure of the abnormal, a firewall relationship? If not is it code problems? Please help everybody see how to solve the problem. thanks?

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  • EXC_BAD_ACCESS when not using self.

    - by chris
    I got nabbed by the following bug again and would like some clarification to exactly why it is a bug. I have a simple UITableView that loads some data: // myclass.h @property (nonatomic, retain) NSArray *myData // myclass.m @synthesize myData; - (void) viewDidLoad { ... myData = someDataSource // note the lack of self } - (UITableViewCell *) cellForRowAtIndexPath ... { ... cell.textLabel.text = [self.myData objectAtIndex:indexPath.row]; // EXC_BAD_ACCESS } The table first loads fine, but when scrolling up enough that one of the cells is totally out of the view I then get the EXC_BAD_ACCESS error. Am I missing something in regards to @property retain. My understanding is that it releases anything that the pointer was previously pointing to before the reassignment. If I am correct then why would not using self. cause any problems? Thanks for the help.

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  • What's the big difference between those two binary files?

    - by Lela Dax
    These are two files (contained in the tar.bz2) that were generated using a just-in-time compiler for a game engine. The generated code from ui-linux.bin is from a x86_64 gcc compiler and the ui-windows.bin from the same brand of compiler but targetting win x86_64 (mingw-w64). I've attempted to debug a problem that occurs only on the windows version and i stumbled upon what it seems to be different end-binary code. However, the input assembly code was virtually identical (only difference being pointer representations as int). (there's theoretically no winabi/unixabi conflict since that's taken care of by an attribute flag on certain declarations involved). Any idea what it might be that makes these two binary codes different? The C for the mini-compiler and base assembly producing it appears compatible at first glance. http://www0.org/vm/bins.tar.bz2

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  • How do I read an arbitrary chunk from a PNG file?

    - by Mason Wheeler
    I've got some custom metadata to put into a PNG file. It's being saved through libpng, and it's not difficult to write out a custom chunk. I just call png_write_chunk with the name, length and data. But I can't see how to get the data back out again. I'd expect there to be a png_read_chunk function that takes a chunk name and returns a pointer to the data or something like that, but there's nothing like that in png.h. Does anyone know how to accomplish this?

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  • shared_ptr requires complete type; cannot use it with lua_State*

    - by topright
    Hello! I'm writing a C++/OOP wrapper for Lua. My code is: class LuaState { boost::shared_ptr<lua_State> L; LuaState(): L( luaL_newstate(), LuaState::CustomDeleter ) { } } The problem is lua_State is incomplete type and shared_ptr constructor requires complete type. And I need safe pointer sharing. (Funny thing boost docs say most functions do not require complete type, but constructor requires, so there is no way of using it. http://www.boost.org/doc/libs/1_42_0/libs/smart_ptr/smart_ptr.htm) Can can I solve this? Thank you.

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  • What is a practical, real world example of the Linked List?

    - by JStims
    I understand the definition of a Linked List, but how can it be represented and related to a common concept or item? For example, inheritance in OOP can be related to automobiles. All (most) automobiles in real life are the essentially same thing; an automobile has an Engine, you can start() it, you can make the car go(), stop() and so on. An automobile would typically have a maximum passenger capacity but it would differ between a Bus and a SportsCar, which are both automobiles. Is there some real life, intuitive example of the plain ole' singly Linked List like we have with inheritance? The typical textbook Linked List example shows a node with an integer and a pointer to the next, and it just doesn't seem very useful. Your input is appreciated.

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  • How to set a reference from one object to another?

    - by Tzur Gazit
    Hi, Imagine the obvious model of employees and departments, where each employee must refer to a single department, and each department may have none to many employees. For Employee I have a pointer to Department, and I set its value to the address of the object of the relevant Department. When I try to save the Employee I get an error: 2010-04-07 10:05:22.491 CoreData2[1112:207] * Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '* -[NSCFDictionary setObject:forKey:]: attempt to insert nil value (key: Department)' I tried, just for testing, to make the reference from Employee to Department optional, but I get the same result. I'm having my first steps in CoreData so please be as clear and simple as you can. Thanks, Tzur.

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  • Objects in interface

    - by Peter Kowalchuk
    I created my own object, PKSurvey. In the interface of the View Controller I can define a pointer to it, then in a method I can alloc it and have an instance. How do I keep the instance beyond the method where it was allocated? I assign values in one method and want to be able to use those values in other methods. Should I allocate it in the viewDidLoad method or should I do it somewhere else? @interface DIrectionalDrillerViewController : UIViewController { PKSurvey *Survey=[PKSurvey new]; ---------------- - (void)viewDidLoad { [Survey new];

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  • How to improve performance

    - by Ram
    Hi, In one of mine applications I am dealing with graphics objects. I am using open source GPC library to clip/merge two shapes. To improve accuracy I am sampling (adding multiple points between two edges) existing shapes. But before displaying back the merged shape I need to remove all the points between two edges. But I am not able to find an efficient algorithm that will remove all points between two edges which has same slope with minimum CPU utilization. Currently all points are of type PointF Any pointer on this will be a great help.

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  • How can I find the places of system calls of my program?

    - by Lucky Man
    From strace manual: -i Print the instruction pointer at the time of the system call. I straced my programm: strace -i prog As a result I got a lot of system calls. One of them: [000da49c] open("./rabbit.o", O_RDONLY) = 3 But disassembled instruction at this address of prog doesn't call any syscall (hte editor): da49c ! mov r7, ip What is wrong? How can I find the places of system calls of my program? P.S. Architecture of my device doesn't support GDB-command catch syscall.

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