Search Results

Search found 1046 results on 42 pages for 'iterator facade'.

Page 7/42 | < Previous Page | 3 4 5 6 7 8 9 10 11 12 13 14  | Next Page >

• Using the Proxy pattern with C++ iterators

  - by Billy ONeal

  Hello everyone :) I've got a moderately complex iterator written which wraps the FindXFile apis on Win32. (See previous question) In order to avoid the overhead of constructing an object that essentially duplicates the work of the WIN32_FIND_DATAW structure, I have a proxy object which simply acts as a sort of const reference to the single WIN32_FIND_DATAW which is declared inside the noncopyable innards of the iterator. This is great because Clients do not pay for construction of irrelevant information they will probably not use (most of the time people are only interested in file names), and Clients can get at all the information provided by the FindXFile APIs if they need or want this information. This becomes an issue though because there is only ever a single copy of the object's actual data. Therefore, when the iterator is incrememnted, all of the proxies are invalidated (set to whatever the next file pointed to by the iterator is). I'm concerned if this is a major problem, because I can think of a case where the proxy object would not behave as somebody would expect: std::vector<MyIterator::value_type> files; std::copy(MyIterator("Hello"), MyIterator(), std::back_inserter(files)); because the vector contains nothing but a bunch of invalid proxies at that point. Instead, clients need to do something like: std::vector<std::wstring> filesToSearch; std::transform( DirectoryIterator<FilesOnly>(L"C:\\Windows\\*"), DirectoryIterator<FilesOnly>(), std::back_inserter(filesToSearch), std::mem_fun_ref(&DirectoryIterator<FilesOnly>::value_type::GetFullFileName) ); Seeing this, I can see why somebody might dislike what the standard library designers did with std::vector<bool>. I'm still wondering though: is this a reasonable trade off in order to achieve (1) and (2) above? If not, is there any way to still achieve (1) and (2) without the proxy?

  Read the article

• C++ iterators, default initialization and what to use as an uninitialized sentinel.

  - by Hassan Syed

  The Context I have a custom template container class put together from a map and vector. The map resolves a string to an ordinal, and the vector resolves an ordinal (only an initial string to ordinal lookup is done, future references are to the vector) to the entry. The entries are modified intrusively to contain a a bool "assigned" and an iterator_type which is a const_iterator to the container class's map. My container class will use RCF's serialization code (which models boost::serialization) to serialize my container classes to nodes in a network. Serializing iterator's is not possible, or a can of worms, and I can easily regenerate them onces the vectors and maps are serialized on the remote site. The Question I need to default initialize, and be able to test that the iterator has not been assigned to (if it is assigned it is valid, if not it is invalid). Since map iterators are not invalidated upon operations performed on it (unless of course items are removed :D) am I to assume that map<x,y>::end() is a valid sentinel (regardless of the state of the map -- i.e., it could be empty) to initialize to ? I will always have access to the parent map, I'm just unsure wheather end() is the same as the map contents change. I don't want to use another level of indirection (--i.e., boost::optional) to achieve my goal, I'd rather forego compiler checks to correct logic, but it would be nice if I didn't need to. Misc This question exists, but most of its content seems non-sense. Assigning a NULL to an iterator is invalid according to g++ and clang++. This is another similar question, but it focuses on the common use-cases of iterators, which generally tends to be using the iterator to iterate, ofcourse in this use-case the state of the container isn't meant to change whilst iteration is going on.

  Read the article

• Trying to write a std::iterator : Compilation error

  - by Naveen

  I am trying to write an std::iterator for the CArray<Type,ArgType> MFC class. This is what I have done till now: template <class Type, class ArgType> class CArrayIterator : public std::iterator<std::random_access_iterator_tag, ArgType> { public: CArrayIterator(CArray<Type,ArgType>& array_in, int index_in = 0) : m_pArray(&array_in), m_index(index_in) { } void operator++() { ++m_index; } void operator++(int) { ++m_index; } void operator--() { --m_index; } void operator--(int) { --m_index; } void operator+=(int n) { m_index += n; } void operator-=(int n) { m_index -= n; } typename ArgType operator*() const{ return m_pArray->GetAt(m_index); } typename ArgType operator->() const { return m_pArray->GetAt(m_index); } bool operator==(const CArrayIterator& other) const { return m_pArray == other.m_pArray && m_index == other.m_index; } bool operator!=(const CArrayIterator& other) const { return ! (operator==(other)); } private: CArray<Type,ArgType>* m_pArray; int m_index; }; I also provided two helper functions to create the iterators like this: template<class Type, class ArgType> CArrayIterator<Type,ArgType> make_begin(CArray<Type,ArgType>& array_in) { return CArrayIterator<Type,ArgType>(array_in, 0); } template<class Type, class ArgType> CArrayIterator<Type,ArgType> make_end(CArray<Type,ArgType>& array_in) { return CArrayIterator<Type,ArgType>(array_in, array_in.GetSize()); } To test the code, I wrote a simple class A and tried to use it like this: class A { public: A(int n): m_i(n) { } int get() const { return m_i; } private: int m_i; }; struct Test { void operator()(A* p) { std::cout<<p->get()<<"\n"; } }; int main(int argc, char **argv) { CArray<A*, A*> b; b.Add(new A(10)); b.Add(new A(20)); std::for_each(make_begin(b), make_end(b), Test()); return 0; } But when I compile this code, I get the following error: Error 4 error C2784: 'bool std::operator <(const std::_Tree<_Traits &,const std::_Tree<_Traits &)' : could not deduce template argument for 'const std::_Tree<_Traits &' from 'CArrayIterator' C:\Program Files\Microsoft Visual Studio 9.0\VC\include\xutility 1564 Vs8Console Can anybody throw some light on what I am doing wrong and how it can be corrected? I am using VC9 compiler if it matters.

  Read the article

• Iterator for boost::variant

  - by Ivan

  Hy there, I'm trying to adapt an existing code to boost::variant. The idea is to use boost::variant for a heterogeneous vector. The problem is that the rest of the code use iterators to access the elements of the vector. Is there a way to use the boost::variant with iterators? I've tried typedef boost::variant<Foo, Bar> Variant; std::vector<Variant> bag; std::vector<Variant>::iterator it; for(it= bag.begin(); it != bag.end(); ++it){ cout<<(*it)<<endl; } But it didn't work.

  Read the article

• Iterator blocks in Clojure?

  - by Checkers

  I am using clojure.contrib.sql to fetch some records from an SQLite database. (defn read-all-foo [] (with-connection *db* (with-query-results res ["select * from foo"] (into [] res)))) Now, I don't really want to realize the whole sequence before returning from the function (i.e. I want to keep it lazy), but if I return res directly or wrap it some kind of lazy wrapper (for example I want to make a certain map transformation on result sequence), SQL-related bindings will be reset and connection will be closed after I return, so realizing the sequence will throw an exception. How can I enclose the whole function in a closure and return a kind of iterator block (like yield in C# or Python)? Or is there another way to return a lazy sequence from this function?

  Read the article

• Making a python iterator go backwards?

  - by uberjumper

  Is there anyway to make a python list iterator to go backwards? Basically i have this class IterTest(object): def __init__(self, data): self.data = data self.__iter = None def all(self): self.__iter = iter(self.data) for each in self.__iter: mtd = getattr(self, type(each).__name__) mtd(each) def str(self, item): print item next = self.__iter.next() while isinstance(next, int): print next next = self.__iter.next() def int(self, item): print "Crap i skipped C" if __name__ == '__main__': test = IterTest(['a', 1, 2,3,'c', 17]) test.all() Running this code results in the output: a 1 2 3 Crap i skipped C I know why it gives me the output, however is there a way i can step backwards in the str() method, by one step?

  Read the article

• Scala downwards or decreasing for loop?

  - by Felix

  In scala, you often use an iterator to do a for loop in an increasing order like: for(i <- 1 to 10){ code } How would you do it so it goes from 10 to 1? I guess 10 to 1 gives an empty iterator (like usual range mathematics)? I made a scala script which solves it by calling reverse on the iterator, but it's not nice in my opinion, is this the way to go: def nBeers(n:Int) = n match { case 0 => ("No more bottles of beer on the wall, no more bottles of beer."+ "\nGo to the store and buy some more, "+ "99 bottles of beer on the wall.\n") case _ => (n+" bottles of beer on the wall, "+n +" bottles of beer.\n"+"Take one down and pass it around, "+ (if((n-1)==0) "no more" else (n-1))+ " bottles of beer on the wall.\n") } for(b <- (0 to 99).reverse)println(nBeers(b)) ?? Any comments/suggestions?

  Read the article

• Iterator blocks and inheritance.

  - by Dave Van den Eynde

  Given a base class with the following interface: public class Base { public virtual IEnumerable<string> GetListOfStuff() { yield return "First"; yield return "Second"; yield return "Third"; } } I want to make a derived class that overrides the method, and adds its own stuff, like so: public class Derived : Base { public override IEnumerable<string> GetListOfStuff() { foreach (string s in base.GetListOfStuff()) { yield return s; } yield return "Fourth"; yield return "Fifth"; } } However, I'm greeted with a warning that "access to a member through a base keyword from an iterator cannot be verified". What's the accepted solution to this problem then?

  Read the article

• comparing two end() iterators

  - by aafoo

  list<int> foo; list<int> foo2; list<int>::iterator foo_end = foo.end(); list<int>::iterator foo2_end = foo2.end(); for (list<int>::iterator it = foo.begin(); it != foo2_end; ++foo) <- notice != comparison here { ... it this allowed? will it work correctly. I am inclined to think that this is implementation dependent, anyone knows if standard says anything about this?

  Read the article

• Anonymous iterator blocks in Clojure?

  - by Checkers

  I am using clojure.contrib.sql to fetch some records from an SQLite database. (defn read-all-foo [] (with-connection *db* (with-query-results res ["select * from foo"] (into [] res)))) Now, I don't really want to realize the whole sequence before returning from the function (i.e. I want to keep it lazy), but if I return res directly or wrap it some kind of lazy wrapper (for example I want to make a certain map transformation on result sequence), SQL-related bindings will be reset and connection will be closed after I return, so realizing the sequence will throw an exception. How can I enclose the whole function in a closure and return a kind of anonymous iterator block (like yield in C# or Python)? Or is there another way to return a lazy sequence from this function?

  Read the article

• Vector.erase(Iterator) causes bad memory access

  - by xon1c

  Hi, I am trying to do a Z-Index reordering of videoObjects stored in a vector. The plan is to identify the videoObject which is going to be put on the first position of the vector, erase it and then insert it at the first position. Unfortunately the erase() function always causes bad memory access. Here is my code: testApp.h: vector<videoObject> videoObjects; vector<videoObject>::iterator itVid; testApp.cpp: // Get the videoObject which relates to the user event for(itVid = videoObjects.begin(); itVid != videoObjects.end(); ++itVid){ if(videoObjects.at(itVid - videoObjects.begin()).isInside(ofPoint(tcur.getX(), tcur.getY()))){ videoObjects.erase(itVid); } } This should be so simple but I just don't see where I'm taking the wrong turn. Thx, xonic

  Read the article

• Iterator to last element in std::list

  - by Dave18

  #include <list> using std::list; int main() { list <int> n; n.push_back(1); n.push_back(2); n.push_back(3); list <int>::iterator iter = n.begin(); std::advance(iter, n.size() - 1); //iter is set to last element } is there any other way to have an iter to the last element in list?

  Read the article

• Input Iterator for a shared_ptr

  - by Baz

  I have an iterator which contains the following functions: ... T &operator*() { return *_i; } std::shared_ptr<T> operator->() { return _i; } private: std::shared_ptr<T> _i; ... How do I get a shared pointer to the internally stored _i? std::shared_ptr<Type> item = ??? Should I do: MyInterfaceIterator<Type> i; std::shared_ptr<Type> item = i.operator->(); Or should I rewrite operator*()?

  Read the article

• Trying to find USB device on iphone with IOKit.framework

  - by HuGeek

  Hi all, i'm working on a project were i need the usb port to communicate with a external device. I have been looking for exemple on the net (Apple and /developer/IOKit/usb exemple) and trying some other but i can't even find the device. In my code i blocking at the place where the fucntion looks for a next iterator (pointer in fact) with the function getNextIterator but never returns a good value so the code is blocking. By the way i am using toolchain and added IOKit.framework in my project. All i what right now is the communicate or do like a ping to someone on the USB bus!! I blocking in the 'FindDevice'....i can't manage to enter in the while because the variable usbDevice is always = to 0....i have tested my code in a small mac program and it works... Thanks Here is my code : IOReturn ConfigureDevice(IOUSBDeviceInterface **dev) { UInt8 numConfig; IOReturn result; IOUSBConfigurationDescriptorPtr configDesc; //Get the number of configurations result = (*dev)->GetNumberOfConfigurations(dev, &numConfig); if (!numConfig) { return -1; } // Get the configuration descriptor result = (*dev)->GetConfigurationDescriptorPtr(dev, 0, &configDesc); if (result) { NSLog(@"Couldn't get configuration descriptior for index %d (err=%08x)\n", 0, result); return -1; } ifdef OSX_DEBUG NSLog(@"Number of Configurations: %d\n", numConfig); endif // Configure the device result = (*dev)->SetConfiguration(dev, configDesc->bConfigurationValue); if (result) { NSLog(@"Unable to set configuration to value %d (err=%08x)\n", 0, result); return -1; } return kIOReturnSuccess; } IOReturn FindInterfaces(IOUSBDeviceInterface *dev, IOUSBInterfaceInterface **itf) { IOReturn kr; IOUSBFindInterfaceRequest request; io_iterator_t iterator; io_service_t usbInterface; IOUSBInterfaceInterface **intf = NULL; IOCFPlugInInterface **plugInInterface = NULL; HRESULT res; SInt32 score; UInt8 intfClass; UInt8 intfSubClass; UInt8 intfNumEndpoints; int pipeRef; CFRunLoopSourceRef runLoopSource; NSLog(@"Debut FindInterfaces \n"); request.bInterfaceClass = kIOUSBFindInterfaceDontCare; request.bInterfaceSubClass = kIOUSBFindInterfaceDontCare; request.bInterfaceProtocol = kIOUSBFindInterfaceDontCare; request.bAlternateSetting = kIOUSBFindInterfaceDontCare; kr = (*dev)->CreateInterfaceIterator(dev, &request, &iterator); usbInterface = IOIteratorNext(iterator); IOObjectRelease(iterator); NSLog(@"Interface found.\n"); kr = IOCreatePlugInInterfaceForService(usbInterface, kIOUSBInterfaceUserClientTypeID, kIOCFPlugInInterfaceID, &plugInInterface, &score); kr = IOObjectRelease(usbInterface); // done with the usbInterface object now that I have the plugin if ((kIOReturnSuccess != kr) || !plugInInterface) { NSLog(@"unable to create a plugin (%08x)\n", kr); return -1; } // I have the interface plugin. I need the interface interface res = (*plugInInterface)->QueryInterface(plugInInterface, CFUUIDGetUUIDBytes(kIOUSBInterfaceInterfaceID), (LPVOID*) &intf); (*plugInInterface)->Release(plugInInterface); // done with this if (res || !intf) { NSLog(@"couldn't create an IOUSBInterfaceInterface (%08x)\n", (int) res); return -1; } // Now open the interface. This will cause the pipes to be instantiated that are // associated with the endpoints defined in the interface descriptor. kr = (*intf)->USBInterfaceOpen(intf); if (kIOReturnSuccess != kr) { NSLog(@"unable to open interface (%08x)\n", kr); (void) (*intf)->Release(intf); return -1; } kr = (*intf)->CreateInterfaceAsyncEventSource(intf, &runLoopSource); if (kIOReturnSuccess != kr) { NSLog(@"unable to create async event source (%08x)\n", kr); (void) (*intf)->USBInterfaceClose(intf); (void) (*intf)->Release(intf); return -1; } CFRunLoopAddSource(CFRunLoopGetCurrent(), runLoopSource, kCFRunLoopDefaultMode); if (!intf) { NSLog(@"Interface is NULL!\n"); } else { *itf = intf; } NSLog(@"End of FindInterface \n \n"); return kr; } unsigned int FindDevice(void *refCon, io_iterator_t iterator) { kern_return_t kr; io_service_t usbDevice; IOCFPlugInInterface **plugInInterface = NULL; HRESULT result; SInt32 score; UInt16 vendor; UInt16 product; UInt16 release; unsigned int count = 0; NSLog(@"Searching Device....\n"); while (usbDevice = IOIteratorNext(iterator)) { // create intermediate plug-in NSLog(@"Found a device!\n"); kr = IOCreatePlugInInterfaceForService(usbDevice, kIOUSBDeviceUserClientTypeID, kIOCFPlugInInterfaceID, &plugInInterface, &score); kr = IOObjectRelease(usbDevice); if ((kIOReturnSuccess != kr) || !plugInInterface) { NSLog(@"Unable to create a plug-in (%08x)\n", kr); continue; } // Now create the device interface result = (*plugInInterface)->QueryInterface(plugInInterface, CFUUIDGetUUIDBytes(kIOUSBDeviceInterfaceID), (LPVOID)&dev); // Don't need intermediate Plug-In Interface (*plugInInterface)->Release(plugInInterface); if (result || !dev) { NSLog(@"Couldn't create a device interface (%08x)\n", (int)result); continue; } // check these values for confirmation kr = (*dev)->GetDeviceVendor(dev, &vendor); kr = (*dev)->GetDeviceProduct(dev, &product); //kr = (*dev)->GetDeviceReleaseNumber(dev, &release); //if ((vendor != LegoUSBVendorID) || (product != LegoUSBProductID) || (release != LegoUSBRelease)) { if ((vendor != LegoUSBVendorID) || (product != LegoUSBProductID)) { NSLog(@"Found unwanted device (vendor = %d != %d, product = %d != %d, release = %d)\n", vendor, kUSBVendorID, product, LegoUSBProductID, release); (void) (*dev)-Release(dev); continue; } // Open the device to change its state kr = (*dev)->USBDeviceOpen(dev); if (kr == kIOReturnSuccess) { count++; } else { NSLog(@"Unable to open device: %08x\n", kr); (void) (*dev)->Release(dev); continue; } // Configure device kr = ConfigureDevice(dev); if (kr != kIOReturnSuccess) { NSLog(@"Unable to configure device: %08x\n", kr); (void) (*dev)->USBDeviceClose(dev); (void) (*dev)->Release(dev); continue; } break; } return count; } // USB rcx Init IOUSBInterfaceInterface** osx_usb_rcx_init (void) { CFMutableDictionaryRef matchingDict; kern_return_t result; IOUSBInterfaceInterface **intf = NULL; unsigned int device_count = 0; // Create master handler result = IOMasterPort(MACH_PORT_NULL, &gMasterPort); if (result || !gMasterPort) { NSLog(@"ERR: Couldn't create master I/O Kit port(%08x)\n", result); return NULL; } else { NSLog(@"Created Master Port.\n"); NSLog(@"Master port 0x:08X \n \n", gMasterPort); } // Set up the matching dictionary for class IOUSBDevice and its subclasses matchingDict = IOServiceMatching(kIOUSBDeviceClassName); if (!matchingDict) { NSLog(@"Couldn't create a USB matching dictionary \n"); mach_port_deallocate(mach_task_self(), gMasterPort); return NULL; } else { NSLog(@"USB matching dictionary : %08X \n", matchingDict); } CFDictionarySetValue(matchingDict, CFSTR(kUSBVendorID), CFNumberCreate(kCFAllocatorDefault, kCFNumberShortType, &LegoUSBVendorID)); CFDictionarySetValue(matchingDict, CFSTR(kUSBProductID), CFNumberCreate(kCFAllocatorDefault, kCFNumberShortType, &LegoUSBProductID)); result = IOServiceGetMatchingServices(gMasterPort, matchingDict, &gRawAddedIter); matchingDict = 0; // this was consumed by the above call // Iterate over matching devices to access already present devices NSLog(@"RawAddedIter : 0x:%08X \n", &gRawAddedIter); device_count = FindDevice(NULL, gRawAddedIter); if (device_count == 1) { result = FindInterfaces(dev, &intf); if (kIOReturnSuccess != result) { NSLog(@"unable to find interfaces on device: %08x\n", result); (*dev)-USBDeviceClose(dev); (*dev)-Release(dev); return NULL; } // osx_usb_rcx_wakeup(intf); return intf; } else if (device_count 1) { NSLog(@"too many matching devices (%d) !\n", device_count); } else { NSLog(@"no matching devices found\n"); } return NULL; } int main(int argc, char *argv[]) { int returnCode; NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init]; NSLog(@"Debut du programme \n \n"); osx_usb_rcx_init(); NSLog(@"Fin du programme \n \n"); return 0; // returnCode = UIApplicationMain(argc, argv, @"Untitled1App", @"Untitled1App"); // [pool release]; // return returnCode; }

  Read the article

• Error of iterator in mys JSP

  - by Mercer

  Hello, in my jsp i do this <table> <tr> <th>TITLLE</th> </tr> <tr class="row0"> <logic:iterate id="listClient" name="Client"> <td> [...] </td> </logic:iterate> </tr> </table> <logic:iterate id="listClient" name="Client"> <table> <tr> <td> [...] </td> </tr> </table> </logic:iterate> But i have this error for my second iterate javax.servlet.jsp.JspException: Cannot create iterator for this collection

  Read the article

• std::list iterator: get next element

  - by sheepsimulator

  I'm trying to build a string using data elements stored in a std::list, where I want commas placed only between the elements (ie, if elements are {A,B,C,D} in list, result string should be "A,B,C,D". This code does not work: typedef std::list< shared_ptr<EventDataItem> > DataItemList; // ... std::string Compose(DataItemList& dilList) { std::stringstream ssDataSegment; for(iterItems = dilList.begin(); iterItems != dilList.end(); iterItems++) { // Lookahead in list to see if next element is end if((iterItems + 1) == dilList.end()) { ssDataSegment << (*iterItems)->ToString(); } else { ssDataSegment << (*iterItems)->ToString() << ","; } } return ssDataSegment.str(); } How do I get at "the-next-item" in a std::list using an iterator? I would expect that it's a linked-list, why can't I get at the next item?

  Read the article

• C# iterator is executed twice when composing two IEnumerable methods

  - by achristoph

  I just started learning about C# iterator but got confused with the flow of the program after reading the output of the program. The foreach with uniqueVals seems to be executed twice. My understanding is that the first few lines up to the line before "Nums in Square: 3" should not be there. Can anyone help to explain why this happens? The output is: Unique: 1 Adding to uniqueVals: 1 Unique: 2 Adding to uniqueVals: 2 Unique: 2 Unique: 3 Adding to uniqueVals: 3 Nums in Square: 3 Unique: 1 Adding to uniqueVals: 1 Square: 1 Number returned from Unique: 1 Unique: 2 Adding to uniqueVals: 2 Square: 2 Number returned from Unique: 4 Unique: 2 Unique: 3 Adding to uniqueVals: 3 Square: 3 Number returned from Unique: 9 static class Program { public static IEnumerable<T> Unique<T>(IEnumerable<T> sequence) { Dictionary<T, T> uniqueVals = new Dictionary<T, T>(); foreach (T item in sequence) { Console.WriteLine("Unique: {0}", item); if (!uniqueVals.ContainsKey(item)) { Console.WriteLine("Adding to uniqueVals: {0}", item); uniqueVals.Add(item, item); yield return item; Console.WriteLine("After Unique yield: {0}", item); } } } public static IEnumerable<int> Square(IEnumerable<int> nums) { Console.WriteLine("Nums in Square: {0}", nums.Count()); foreach (int num in nums) { Console.WriteLine("Square: {0}", num); yield return num * num; Console.WriteLine("After Square yield: {0}", num); } } static void Main(string[] args) { var nums = new int[] { 1, 2, 2, 3 }; foreach (int num in Square(Unique(nums))) Console.WriteLine("Number returned from Unique: {0}", num); Console.Read(); } }

  Read the article

• Boost ASIO async_write "Vector iterator not dereferencable"

  - by xeross

  Hey, I've been working on an async boost server program, and so far I've got it to connect. However I'm now getting a "Vector iterator not dereferencable" error. I suspect the vector gets destroyed or dereferenced before he packet gets sent thus causing the error. void start() { Packet packet; packet.setOpcode(SMSG_PING); send(packet); } void send(Packet packet) { cout << "DEBUG> Transferring packet with opcode " << packet.GetOpcode() << endl; async_write(m_socket, buffer(packet.write()), boost::bind(&Session::writeHandler, shared_from_this(), placeholders::error, placeholders::bytes_transferred)); } void writeHandler(const boost::system::error_code& errorCode, size_t bytesTransferred) { cout << "DEBUG> Transfered " << bytesTransferred << " bytes to " << m_socket.remote_endpoint().address().to_string() << endl; } Start gets called once a connection is made. packet.write() returns a uint8_t vector Would it matter if I'd change void send(Packet packet) to void send(Packet& packet) Not in relation to this problem but performance wise.

  Read the article

• List iterator not dereferencable?

  - by Roderick

  Hi All I get the error "list iterator not dereferencable" when using the following code: bool done = false; while (!_list_of_messages.empty() && !done) { // request the next message to create a frame // DEBUG ERROR WHEN NEXT LINE IS EXECUTED: Counted_message_reader reader = *(_list_of_messages.begin()); if (reader.has_more_data()) { _list_of_frames.push_back(new Dlp_data_frame(reader, _send_compressed_frames)); done = true; } else { _list_of_messages.pop_front(); } } (The line beginning with "Counted_message_reader..." is the one giving the problem) Note that the error doesn't always occur but seemingly at random times (usually when there's lots of buffered data). _list_of_messages is declared as follows: std::list<Counted_message_reader> _list_of_messages; In the surrounding code we could do pop_front, push_front and size, empty or end checks on _list_of_messages but no erase calls. I've studied the STL documentation and can't see any glaring problems. Is there something wrong with the above code or do I have a memory leak somewhere? Thanks! Appreciated!

  Read the article

• stringstream problem - vector iterator not dereferencable

  - by andreas

  Hello I've got a problem with the following code snippet. It is related to the stringstream "stringstream css(cv.back())" bit. If it is commented out the program will run ok. It is really weird, as I keep getting it in some of my programs, but if I just create a console project the code will run fine. In some of my Win32 programs it will and in some it won't (then it will return "vector iterator not dereferencable" but it will compile just fine). Any ideas at all would be really appreciated. Thanks! vector<double> cRes(2); vector<double> pRes(2); int readTimeVects2(vector<double> &cRes, vector<double> &pRes){ string segments; vector<string> cv, pv, chv, phv; ifstream cin("cm.txt"); ifstream pin("pw.txt"); ifstream chin("hm.txt"); ifstream phin("hw.txt"); while (getline(cin,segments,'\t')) { cv.push_back(segments); } while (getline(pin,segments,'\t')) { pv.push_back(segments); } while (getline(chin,segments,'\t')) { chv.push_back(segments); } while (getline(phin,segments,'\t')) { phv.push_back(segments); } cin.close(); pin.close(); chin.close(); phin.close(); stringstream phss(phv.front()); phss >> pRes[0]; phss.clear(); stringstream chss(chv.front()); chss >> cRes[0]; chss.clear(); stringstream pss(pv.back()); pss >> pRes[1]; pss.clear(); stringstream css(cv.back()); css >> cRes[1]; css.clear(); return 0; }

  Read the article

• How are iterators and pointers related?

  - by sharptooth

  Code with iterators looks pretty much like code with pointers. Iterators are of some obscure type (like std::vector<int>::iterator for example). What I don't get is how iterators and pointer are related to each other - is an iterator a wrapper around a pointer with overloaded operations to advance to adjacent elements or is it something else?

  Read the article

• multi_index composite_key replace with iterator

  - by Rohit

  Is there anyway to loop through an index in a boost::multi_index and perform a replace? #include <iostream> #include <string> #include <boost/multi_index_container.hpp> #include <boost/multi_index/composite_key.hpp> #include <boost/multi_index/member.hpp> #include <boost/multi_index/ordered_index.hpp> using namespace boost::multi_index; using namespace std; struct name_record { public: name_record(string given_name_,string family_name_,string other_name_) { given_name=given_name_; family_name=family_name_; other_name=other_name_; } string given_name; string family_name; string other_name; string get_name() const { return given_name + " " + family_name + " " + other_name; } void setnew(string chg) { given_name = given_name + chg; family_name = family_name + chg; } }; struct NameIndex{}; typedef multi_index_container< name_record, indexed_by< ordered_non_unique< tag<NameIndex>, composite_key < name_record, BOOST_MULTI_INDEX_MEMBER(name_record,string, name_record::given_name), BOOST_MULTI_INDEX_MEMBER(name_record,string, name_record::family_name) > > > > name_record_set; typedef boost::multi_index::index<name_record_set,NameIndex>::type::iterator IteratorType; typedef boost::multi_index::index<name_record_set,NameIndex>::type NameIndexType; void printContainer(name_record_set & ns) { cout << endl << "PrintContainer" << endl << "-------------" << endl; IteratorType it1 = ns.begin(); IteratorType it2 = ns.end (); while (it1 != it2) { cout<<it1->get_name()<<endl; it1++; } cout << "--------------" << endl << endl; } void modifyContainer(name_record_set & ns) { cout << endl << "ModifyContainer" << endl << "-------------" << endl; IteratorType it3; IteratorType it4; NameIndexType & idx1 = ns.get<NameIndex>(); IteratorType it1 = idx1.begin(); IteratorType it2 = idx1.end(); while (it1 != it2) { cout<<it1->get_name()<<endl; name_record nr = *it1; nr.setnew("_CHG"); bool res = idx1.replace(it1,nr); cout << "result is: " << res << endl; it1++; } cout << "--------------" << endl << endl; } int main() { name_record_set ns; ns.insert( name_record("Joe","Smith","ENTRY1") ); ns.insert( name_record("Robert","Brown","ENTRY2") ); ns.insert( name_record("Robert","Nightingale","ENTRY3") ); ns.insert( name_record("Marc","Tuxedo","ENTRY4") ); printContainer (ns); modifyContainer (ns); printContainer (ns); return 0; } PrintContainer ------------- Joe Smith ENTRY1 Marc Tuxedo ENTRY4 Robert Brown ENTRY2 Robert Nightingale ENTRY3 -------------- ModifyContainer ------------- Joe Smith ENTRY1 result is: 1 Marc Tuxedo ENTRY4 result is: 1 Robert Brown ENTRY2 result is: 1 -------------- PrintContainer ------------- Joe_CHG Smith_CHG ENTRY1 Marc_CHG Tuxedo_CHG ENTRY4 Robert Nightingale ENTRY3 Robert_CHG Brown_CHG ENTRY2 --------------

  Read the article

• private class calling a method from its outer class

  - by oxinabox.ucc.asn.au

  Ok, so I have a class for a "Advanced Data Structure" (in this case a kinda tree) SO I implimented a Iterator as a private class with in it. So the iterator needs to implement a remove function to remove the last retuirned element. now my ADT already impliments a remove function, and in this case there is very little (thinking about it, i think nothing) to be gain by implimenting a different remove function for the iterator. so how do I go about calling the remove from my ADT sketch of my struture: public class ADT { ... private class ADT_Iterator impliments java.util.Itorator{ ... public void remove(){ //where I want to call the ADT's remove function from } ... public void remove( Object paramFoo ) { ... } ... } So just calling remove(FooInstance) won't work (will it?) and this.remove(FooInstance) is the same thing. what do i call? (and changign the name of the ADT's remove function is not an option, as that AD T has to meet an Interace wich I am note at liberty to change) I could make both of them call a removeHelper functon, I guess...

  Read the article

• Pushing a vector into an vector

  - by Sunil

  I have a 2d vector typedef vector <double> record_t; typedef vector <record_t> data_t; data_t data; So my 2d vector is data here. It has elements like say, 1 1 1 1 1 2 2 2 2 2 3 3 3 3 3 4 4 4 4 4 5 5 5 5 5 Now I want to insert these elements into another 2d vector std::vector< vector<double> > window; So what I did was to create an iterator for traversing through the rows of data and pushing it into window like std::vector< std::vector<double> >::iterator data_it; for (data_it = data.begin() ; data_it != data.end() ; ++data_it){ window.push_back ( *data_it ); // Do something else } Can anybody tell me where I'm wrong or suggest a way to do this ? BTW I want to push it just element by element because I want to be able to do something else inside the loop too. i.e. I want to check for a condition and increment the value of the iterator inside. for example, if a condition satisfies then I'll do data_it+=3 or something like that inside the loop. Thanks P.S. I asked this question last night and didn't get any response and that's why I'm posting it again.

  Read the article

• Deleting elements from stl set while iterating through it does not invalidate the iterators.

  - by pedromanoel

  I need to go through a set and remove elements that meet a predefined criteria. This is the test code I wrote: #include <set> #include <algorithm> void printElement(int value) { std::cout << value << " "; } int main() { int initNum[] = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 }; std::set<int> numbers(initNum, initNum + 10); // print '0 1 2 3 4 5 6 7 8 9' std::for_each(numbers.begin(), numbers.end(), printElement); std::set<int>::iterator it = numbers.begin(); // iterate through the set and erase all even numbers for (; it != numbers.end(); ++it) { int n = *it; if (n % 2 == 0) { // wouldn't invalidate the iterator? numbers.erase(it); } } // print '1 3 5 7 9' std::for_each(numbers.begin(), numbers.end(), printElement); return 0; } At first, I thought that erasing an element from the set while iterating through it would invalidate the iterator, and the increment at the for loop would have undefined behavior. Even though, I executed this test code and all went well, and I can't explain why. My question: Is this the defined behavior for std sets or is this implementation specific? I am using gcc 4.3.3 on ubuntu 10.04 (32-bit version), by the way. Thanks!

  Read the article

< Previous Page | 3 4 5 6 7 8 9 10 11 12 13 14  | Next Page >