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  • Creating lots of arrays

    - by Dmitry
    Hello, everybody! May be that is a stupid question. How to create, say, 30 arrays (it doesn't matter of what type, say, char[])? It seems to me that it is not a good idea, to create them one by one by hand. I want to do that using a "for" cycle, but how should I specify identifiers?

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  • Need to convert int value to hex value

    - by SA
    Hi, I need to convert char to hex values. Refer to the Ascii table but I have a few examples listed below: int 1 = 31 2 = 32 3 = 33 4 = 34 5 = 35 A = 41 a = 61 etc Therefore int test = 12345; Need to get the converted i = 3132333435

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  • How to solve Memory leaks in Lib Xml Parser in objective-C where the list is returned?

    - by Madan Mohan
    Hi Guys, I got leaks in Lib Xml Parser while retrieving the data from the net, Here in the below code, I have allocated the list - (void)getCustomersList { // make an operation so we can push it into the queue SEL method = @selector(parseForData); NSInvocationOperation *op = [[NSInvocationOperation alloc] initWithTarget:self selector:method object:nil]; customersTempList = [[NSMutableArray alloc] initWithCapacity:20];// allocated list [self.retrieverQueue addOperation:op]; [op release]; } // return each recode // in parser .m class one of the condition in endElement where it shows a leak. else if(0 == strncmp((const char *)localname, kCustomerElement, kCustomerElementLength)) { [customersTempList addObject:customer]; printf("\n no of objects in temp list:%d", [customersTempList count]); if ([customersTempList count] == 20) { NSMutableArray* argsList = [customersTempList copy];//////////////////////here it is showing leak. printf("\n Calling reload data with %d new objects", [argsList count]); SEL selector = @selector(parser:addCustomerObject:); NSMethodSignature *sig = [(id)self.delegate methodSignatureForSelector:selector]; if(nil != sig && [self.delegate respondsToSelector:selector]) { NSInvocation *invocation = [NSInvocation invocationWithMethodSignature:sig]; [invocation retainArguments]; [invocation setTarget:self.delegate]; [invocation setSelector:selector]; [invocation setArgument:&self atIndex:2]; [invocation setArgument:&argsList atIndex:3]; [invocation performSelectorOnMainThread:@selector(invoke) withObject:NULL waitUntilDone:NO]; } [customersTempList removeAllObjects]; } } // returned the list after all the records are stored in the list else if(0 == strncmp((const char *)localname, kCustomersElement, kCustomersElementLength)) { printf("\n Calling reload data with %d new objects", [customersTempList count]); NSMutableArray* argsList = [customersTempList copy]; printf("\n Calling reload data with %d new objects", [argsList count]); SEL selector = @selector(parser:addCustomerObject:); NSMethodSignature *sig = [(id)self.delegate methodSignatureForSelector:selector]; if(nil != sig && [self.delegate respondsToSelector:selector]) { NSInvocation *invocation = [NSInvocation invocationWithMethodSignature:sig]; [invocation retainArguments]; [invocation setTarget:self.delegate]; [invocation setSelector:selector]; [invocation setArgument:&self atIndex:2]; [invocation setArgument:&argsList atIndex:3]; [invocation performSelectorOnMainThread:@selector(invoke) withObject:NULL waitUntilDone:NO]; } [customersTempList removeAllObjects]; } } please help me out of this, Thanks, Madan.

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  • Recommendations for a C++ polymorphic, seekable, binary I/O interface

    - by Trevor Robinson
    I've been using std::istream and ostream as a polymorphic interface for random-access binary I/O in C++, but it seems suboptimal in numerous ways: 64-bit seeks are non-portable and error-prone due to streampos/streamoff limitations; currently using boost/iostreams/positioning.hpp as a workaround, but it requires vigilance Missing operations such as truncating or extending a file (ala POSIX ftruncate) Inconsistency between concrete implementations; e.g. stringstream has independent get/put positions whereas filestream does not Inconsistency between platform implementations; e.g. behavior of seeking pass the end of a file or usage of failbit/badbit on errors Don't need all the formatting facilities of stream or possibly even the buffering of streambuf streambuf error reporting (i.e. exceptions vs. returning an error indicator) is supposedly implementation-dependent in practice I like the simplified interface provided by the Boost.Iostreams Device concept, but it's provided as function templates rather than a polymorphic class. (There is a device class, but it's not polymorphic and is just an implementation helper class not necessarily used by the supplied device implementations.) I'm primarily using large disk files, but I really want polymorphism so I can easily substitute alternate implementations (e.g. use stringstream instead of fstream for unit tests) without all the complexity and compile-time coupling of deep template instantiation. Does anyone have any recommendations of a standard approach to this? It seems like a common situation, so I don't want to invent my own interfaces unnecessarily. As an example, something like java.nio.FileChannel seems ideal. My best solution so far is to put a thin polymorphic layer on top of Boost.Iostreams devices. For example: class my_istream { public: virtual std::streampos seek(stream_offset off, std::ios_base::seekdir way) = 0; virtual std::streamsize read(char* s, std::streamsize n) = 0; virtual void close() = 0; }; template <class T> class boost_istream : public my_istream { public: boost_istream(const T& device) : m_device(device) { } virtual std::streampos seek(stream_offset off, std::ios_base::seekdir way) { return boost::iostreams::seek(m_device, off, way); } virtual std::streamsize read(char* s, std::streamsize n) { return boost::iostreams::read(m_device, s, n); } virtual void close() { boost::iostreams::close(m_device); } private: T m_device; };

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  • C++ Class Templates (Queue of a class)

    - by Dalton Conley
    Ok, so I have my basic linked Queue class with basic functions such as front(), empty() etc.. and I have transformed it into a template. Now, I also have a class called Student. Which holds 2 values: Student name and Student Id. I can print out a student with the following code.. Student me("My Name", 2); cout << me << endl; Here is my display function for student: void display(ostream &out) const { out << "Student Name: " << name << "\tStudent Id: " << id << "\tAddress: " << this << endl; } Now it works fine, you can see the basic output. Now I'm declaring a queue like so.. Queue<Student> qstu; Storing data in this queue is fine, I can add new values and such.. now what I'm trying to do is print out my whole queue of students with: cout << qstu << endl; But its simply returning an address.. here is my display function for queues. void display(ostream & out) const { NodePointer ptr; ptr = myFront; while(ptr != NULL) { out << ptr->data << " "; ptr = ptr->next; } out << endl; } Now, based on this, I assume ptr-data is a Student type and I would assume this would work, but it doesn't. Is there something I'm missing? Also, when I Try: ptr->data.display(out); (Making the assumtion ptr-data is of type student, it does not work which tells me I am doing something wrong. Help on this would be much appreciated!

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  • Dojo script (fx.xd.js) not working IE

    - by Andy Walpole
    Hi folks, I've been teaching myself Dojo over the last few days... However, if you look at the following page: http://www.mechanic-one.suburban-glory.com/ You'll see that the simple script in the header doesn't work in IE I get the following message: Message: 'duration' is null or not an object Line: 8 Char: 622 Code: 0 URI: htt p://ajax.googleapis.com/ajax/libs/dojo/1.3.2/dojo/fx.xd.js Do you have any ideas why this is so? Andy

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  • generic programming in C with void pointer.

    - by Nyan
    Hi everyone, even though it is possible to write generic code in C using void pointer(generic pointer), I find that it is quite difficult to debug the code since void pointer can take any pointer type without warning from compiler. (e.g function foo() take void pointer which is supposed to be pointer to struct, but compiler won't complain if char array is passed.) What kind of approach/strategy do you all use when using void pointer in C?

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  • transforming from 'Y' or 'N' to bit

    - by rap-uvic
    Hello, I have a table which has a column called Direct of type char(1). It's values are either 'Y' or 'N' or NULL. I am creating a view and I want the value to be transformed to either 0 or 1 of type bit. Right now it's of type INT. How do I go about doing this? Following is the code: CASE WHEN Direct = 'Y' THEN (SELECT 1) WHEN Direct <> 'Y' THEN (SELECT 0) END AS DirectDebit

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  • How CudaMalloc work?

    - by kitw
    I am trying to modify the imageDenosing class in CUDA SDK, I need to repeat the filter many time incase to capture the time. But my code doesn't work properly. //start __global__ void F1D(TColor *image,int imageW,int imageH, TColor *buffer) { const int ix = blockDim.x * blockIdx.x + threadIdx.x; const int iy = blockDim.y * blockIdx.y + threadIdx.y; if(iy != 0 && iy < imageH-1 && ix < imageW) { float4 fresult = get_color(image[imageW * iy + ix]); float4 fresult4 = get_color(image[imageW * (iy+1) + ix]); float4 fresult5 = get_color(image[imageW * (iy-1) + ix]); float4 fresult7; fresult7.x = fresult.x*0.5+fresult4.x*.25+fresult5.x*.25; fresult7.y = fresult.y*0.5+fresult4.y*.25+fresult5.y*.25; fresult7.z = fresult.z*0.5+fresult4.z*.25+fresult5.z*.25; buffer[imageW * iy + ix] = make_color(fresult7.x,fresult7.y,fresult7.z,0); } image[imageW * iy + ix] = buffer[imageW * iy + ix]; //should be use cudaMemcpy, But it fails } //extern extern "C" void cuda_F1D(TColor *dst, int imageW, int imageH) { dim3 threads(BLOCKDIM_X, BLOCKDIM_Y); dim3 grid(iDivUp(imageW, BLOCKDIM_X), iDivUp(imageH, BLOCKDIM_Y)); Copy<<<grid, threads>>>(dst, imageW, imageH); size_t size = imageW*imageH*sizeof(TColor); TColor *host =(TColor*) malloc(size); TColor *dst2; //TColor *dst3; //TColor *d = new TColor(imageW*imageH*sizeof(TColor)); dim3 threads2(imageW,1); dim3 grid2(iDivUp(imageW, imageW), iDivUp(imageH, 1)); *for(int i = 0;i<1;i++) { cudaMalloc( (void **)&dst2, size); cudaMemcpy(dst2, dst, imageW*imageH*sizeof(TColor),cudaMemcpyHostToDevice); //cudaMalloc( (void **)&dst3, imageW*imageH*sizeof(TColor)); //cudaMemcpy(dst3, dst, imageW*imageH*sizeof(TColor),cudaMemcpyHostToDevice); F1D<<<grid2, threads2>>>(dst, imageW, imageH,dst2); //cudaMemcpy(dst, dst3, imageW*imageH*sizeof(TColor),cudaMemcpyDeviceToHost); cudaFree(dst2); }* } This code works, but cant synchronise the array of image. and lead to many synchronise problem

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  • How can I get a file's size in C?

    - by Nino
    How can I find out the size of a file? I opened with an application written in C. I would like to know the size, because I want to put the content of the loaded file into a string, which I alloc using malloc(). Just writing malloc(10000*sizeof(char)); is IMHO a bad idea.

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  • Calling assignment operator in copy constructor

    - by stas
    Are there some drawbacks of such implementation of copy-constructor? Foo::Foo(const Foo& i_foo) { *this = i_foo; } As I remember, it was recommend in some book to call copy constructor from assignment operator and use well-known swap trick, but I don't remember, why...

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  • How to concatenate 2 LPOLESTR

    - by BHOdevelopper
    Hi, i want to concatenate 2 strings in c++, i can't use char*. I tried the following but doesn't work: #define url L"http://domain.com" wstring s1 = url; wstring s2 = L"/page.html"; wstring s = s1 + s2; LPOLESTR o = OLESTR(s); I need a string with s1 and s2 concatenated. Any info or website that explain more about this ? Thanks.

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  • UNIQUE CONSTRAINT on a column from foreign table in MSSQL2008

    - by bodziec
    Hi, I have two tables: create table [dbo].[Main] ( [ID] [int] identity(1,1) primary key not null, [Sign] [char](1) not null ) create table [dbo].[Names] ( [ID_Main][int] primary key not null, [Name][nvarchar](128) not null, constraint [FK_Main_Users] foreign key ([ID_Main]) references [dbo].[Main]([ID]), constraint [CK_Name] unique ([Name], [Sign]) ) The problem is with the second constraint CK_Name Is there a way to make a constraint target column from a foreign table?

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  • finding "distance" between two pixel's colors.

    - by igor
    Once more something relatively simple, but confused as to what they want. the method to find distance on cartesian coordinate system is distance=sqrt[(x2-x1)^2 + (y2-y1)^2] but how do i apply it here? //Requires: testColor to be a valid Color //Effects: returns the "distance" between the current Pixel's color and // the passed color // uses the standard method to calculate "distance" // uses the same formula as finding distance on a // Cartesian coordinate system double colorDistance(Color testColor) const;

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  • operator "new" returning a non-local heap pointer for only one class ?

    - by KaluSingh Gabbar
    Language : C++ Platform : Windows Server 2003 I have an exe calling a DLL, in which when I allocate (new) the memory for class A (which is in DLL) it returns me a non-local heap pointer. I try to new other classes which are in DLL and "new" returns a valid heap pointer for them, its only Class A which is not being allocated properly. I am on windows and validating the heap by this function call : _CrtIsValidHeapPointer ( (const void *) pPtr ) I am seriously confused why this only happens with new-ing Class A and no other class ? (All Native Code)

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  • Good style for handling constructor failure of critical object

    - by mtlphil
    I'm trying to decide between two ways of instantiating an object & handling any constructor exceptions for an object that is critical to my program, i.e. if construction fails the program can't continue. I have a class SimpleMIDIOut that wraps basic Win32 MIDI functions. It will open a MIDI device in the constructor and close it in the destructor. It will throw an exception inherited from std::exception in the constructor if the MIDI device cannot be opened. Which of the following ways of catching constructor exceptions for this object would be more in line with C++ best practices Method 1 - Stack allocated object, only in scope inside try block #include <iostream> #include "simplemidiout.h" int main() { try { SimpleMIDIOut myOut; //constructor will throw if MIDI device cannot be opened myOut.PlayNote(60,100); //..... //myOut goes out of scope outside this block //so basically the whole program has to be inside //this block. //On the plus side, it's on the stack so //destructor that handles object cleanup //is called automatically, more inline with RAII idiom? } catch(const std::exception& e) { std::cout << e.what() << std::endl; std::cin.ignore(); return 1; } std::cin.ignore(); return 0; } Method 2 - Pointer to object, heap allocated, nicer structured code? #include <iostream> #include "simplemidiout.h" int main() { SimpleMIDIOut *myOut; try { myOut = new SimpleMIDIOut(); } catch(const std::exception& e) { std::cout << e.what() << std::endl; delete myOut; return 1; } myOut->PlayNote(60,100); std::cin.ignore(); delete myOut; return 0; } I like the look of the code in Method 2 better, don't have to jam my whole program into a try block, but Method 1 creates the object on the stack so C++ manages the object's life time, which is more in tune with RAII philosophy isn't it? I'm still a novice at this so any feedback on the above is much appreciated. If there's an even better way to check for/handle constructor failure in a siatuation like this please let me know.

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  • Error in ternary expression

    - by Bipul
    Consider the following code which shows compile time error : #include <stdio.h> int main(int argc, char** argv) { int x=5,y=0,z=2; int a=z?x,y?x:(y); // but z?x,y?x:y:z is not showing any error printf("%d",a); return 0; } Please help me explain the reason why z?x,y?x:y:z is not showing any error?

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  • SQLite bulk insert on iPhone not working

    - by App_beginner
    Hi. I have been struggling with this seeminly easy problem for 48 hours, and I am no closer to a solution. So I was hoping that someone might be able to help me. I am building a app, that use a combination of a local (SQLite) database and an online database (PHP/MYSQL). The app is nearly finished. Checked for leaks and work like a charm. However the very last part is the part I have struggled with. On launch, I want the app to check for changes to the online databse, and if there is. I want it to download and parse a xml file containing the changes. Everything is working fine this far. But when I try to bulk insert my parsed data to my database, the app crashes, giving a NSInternalInconsistency error. Due to the database returning SQLITE_MISUSE. I have done a lot of googling, but am still unable to solve my problem. So I am putting the code here, hoping that someone can help me fix this. And I know that I should have used core data for this. But this is the very last part I am struggling with, and I am very reluctant to changing my entire code now. Core data will have to come in the update. Here is the error I recieve: Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'Error while inserting data. 'library routine called out of sequence'' Here is my code: -(void)UpdateDatabase:(const char *)_query NewValues:(NSMutableArray *)_odb dbn:(NSString *)_dbn dbp:(NSString *)_dbp { sqlite3 *database; NSMutableArray *NewValues = _odb; int i; const char *query = _query; sqlite3_stmt *addStmt; for (i = 1; i < [NewValues count]; i++) { if(sqlite3_prepare_v2(database, query, -1, &addStmt, NULL) == SQLITE_OK) { sqlite3_bind_text(addStmt, 1, [[[NewValues objectAtIndex:i] name] UTF8String], -1, SQLITE_TRANSIENT); sqlite3_bind_text(addStmt, 2, [[[NewValues objectAtIndex:i] city]UTF8String], -1, SQLITE_TRANSIENT); sqlite3_bind_double(addStmt, 3, [[[NewValues objectAtIndex:i] lat] doubleValue]); sqlite3_bind_int(addStmt, 4, [[[NewValues objectAtIndex:i] long] doubleValue]); sqlite3_bind_int(addStmt, 5, [[[NewValues objectAtIndex:i] code] intValue]); } if(SQLITE_DONE != sqlite3_step(addStmt)) { NSAssert1(0, @"Error while inserting data. '%s'", sqlite3_errmsg(database)); } //Reset the add statement. sqlite3_reset(addStmt); } }

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  • C++0x Overload on reference, versus sole pass-by-value + std::move?

    - by dean
    It seems the main advice concerning C++0x's rvalues is to add move constructors and move operators to your classes, until compilers default-implement them. But waiting is a losing strategy if you use VC10, because automatic generation probably won't be here until VC10 SP1, or in worst case, VC11. Likely, the wait for this will be measured in years. Here lies my problem. Writing all this duplicate code is not fun. And it's unpleasant to look at. But this is a burden well received, for those classes deemed slow. Not so for the hundreds, if not thousands, of smaller classes. ::sighs:: C++0x was supposed to let me write less code, not more! And then I had a thought. Shared by many, I would guess. Why not just pass everything by value? Won't std::move + copy elision make this nearly optimal? Example 1 - Typical Pre-0x constructor OurClass::OurClass(const SomeClass& obj) : obj(obj) {} SomeClass o; OurClass(o); // single copy OurClass(std::move(o)); // single copy OurClass(SomeClass()); // single copy Cons: A wasted copy for rvalues. Example 2 - Recommended C++0x? OurClass::OurClass(const SomeClass& obj) : obj(obj) {} OurClass::OurClass(SomeClass&& obj) : obj(std::move(obj)) {} SomeClass o; OurClass(o); // single copy OurClass(std::move(o)); // zero copies, one move OurClass(SomeClass()); // zero copies, one move Pros: Presumably the fastest. Cons: Lots of code! Example 3 - Pass-by-value + std::move OurClass::OurClass(SomeClass obj) : obj(std::move(obj)) {} SomeClass o; OurClass(o); // single copy, one move OurClass(std::move(o)); // zero copies, two moves OurClass(SomeClass()); // zero copies, one move Pros: No additional code. Cons: A wasted move in cases 1 & 2. Performance will suffer greatly if SomeClass has no move constructor. What do you think? Is this correct? Is the incurred move a generally acceptable loss when compared to the benefit of code reduction?

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