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• How can I use the Boost Graph Library to lay out verticies?

  - by Mike

  I'm trying to lay out vertices using the Boost Graph Library. However, I'm running into some compilation issues which I'm unsure about. Am I using the BGL in an improper manner? My code is: PositionVec position_vec(2); PositionMap position(position_vec.begin(), get(vertex_index, g)); int iterations = 100; double width = 100.0; double height = 100.0; minstd_rand gen; rectangle_topology<> topology(gen, 0, 0, 100, 100); fruchterman_reingold_force_directed_layout(g, position, topology); //Compile fails on this line The diagnostics produced by clang++(I've also tried GCC) are: In file included from test.cpp:2: /Volumes/Data/mike/Downloads/boost_1_43_0/boost/graph/fruchterman_reingold.hpp:95:3: error: no member named 'dimensions' in 'boost::simple_point<double>' BOOST_STATIC_ASSERT (Point::dimensions == 2); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ In file included from test.cpp:2: In file included from /Volumes/Data/mike/Downloads/boost_1_43_0/boost/graph/fruchterman_reingold.hpp:13: In file included from /Volumes/Data/mike/Downloads/boost_1_43_0/boost/graph/graph_traits.hpp:15: In file included from /Volumes/Data/mike/Downloads/boost_1_43_0/boost/tuple/tuple.hpp:24: /Volumes/Data/mike/Downloads/boost_1_43_0/boost/static_assert.hpp:118:49: note: instantiated from: sizeof(::boost::STATIC_ASSERTION_FAILURE< BOOST_STATIC_ASSERT_BOOL_CAST( B ) >)>\ ^ In file included from test.cpp:2: /Volumes/Data/mike/Downloads/boost_1_43_0/boost/graph/fruchterman_reingold.hpp:95:3: note: instantiated from: BOOST_STATIC_ASSERT (Point::dimensions == 2); ^ ~~~~~~~ /Volumes/Data/mike/Downloads/boost_1_43_0/boost/graph/fruchterman_reingold.hpp:95:31: note: instantiated from: BOOST_STATIC_ASSERT (Point::dimensions == 2); ~~~~~~~^ /Volumes/Data/mike/Downloads/boost_1_43_0/boost/graph/fruchterman_reingold.hpp:417:19: note: in instantiation of template class 'boost::grid_force_pairs<boost::rectangle_topology<boost::random::linear_congruential<int, 48271, 0, 2147483647, 399268537> >, boost::iterator_property_map<__gnu_cxx::__normal_iterator<boost::simple_point<double> *, std::vector<boost::simple_point<double>, std::allocator<boost::simple_point<double> > > >, boost::vec_adj_list_vertex_id_map<boost::property<boost::vertex_name_t, std::basic_string<char>, boost::no_property>, unsigned long>, boost::simple_point<double>, boost::simple_point<double> &> >' requested here make_grid_force_pairs(topology, position, g)), ^ /Volumes/Data/mike/Downloads/boost_1_43_0/boost/graph/fruchterman_reingold.hpp:431:3: note: in instantiation of function template specialization 'boost::fruchterman_reingold_force_directed_layout<boost::rectangle_topology<boost::random::linear_congruential<int, 48271, 0, 2147483647, 399268537> >, boost::adjacency_list<boost::listS, boost::vecS, boost::undirectedS, boost::property<boost::vertex_name_t, std::basic_string<char>, boost::no_property>, boost::no_property, boost::no_property, boost::listS>, boost::iterator_property_map<__gnu_cxx::__normal_iterator<boost::simple_point<double> *, std::vector<boost::simple_point<double>, std::allocator<boost::simple_point<double> > > >, boost::vec_adj_list_vertex_id_map<boost::property<boost::vertex_name_t, std::basic_string<char>, boost::no_property>, unsigned long>, boost::simple_point<double>, boost::simple_point<double> &>, boost::square_distance_attractive_force, boost::attractive_force_t, boost::no_property>' requested here fruchterman_reingold_force_directed_layout ^ test.cpp:48:3: note: in instantiation of function template specialization 'boost::fruchterman_reingold_force_directed_layout<boost::rectangle_topology<boost::random::linear_congruential<int, 48271, 0, 2147483647, 399268537> >, boost::adjacency_list<boost::listS, boost::vecS, boost::undirectedS, boost::property<boost::vertex_name_t, std::basic_string<char>, boost::no_property>, boost::no_property, boost::no_property, boost::listS>, boost::iterator_property_map<__gnu_cxx::__normal_iterator<boost::simple_point<double> *, std::vector<boost::simple_point<double>, std::allocator<boost::simple_point<double> > > >, boost::vec_adj_list_vertex_id_map<boost::property<boost::vertex_name_t, std::basic_string<char>, boost::no_property>, unsigned long>, boost::simple_point<double>, boost::simple_point<double> &> >' requested here fruchterman_reingold_force_directed_layout(g, position, topology); ^ 1 error generated.

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• should std::auto_ptr<>::operator = reset / deallocate its existing pointee ?

  - by afriza

  I read here about std::auto_ptr<::operator= Notice however that the left-hand side object is not automatically deallocated when it already points to some object. You can explicitly do this by calling member function reset before assigning it a new value. However, when I read the source code for header file C:\Program Files\Microsoft Visual Studio 8\VC\ce\include\memory template<class _Other> auto_ptr<_Ty>& operator=(auto_ptr<_Other>& _Right) _THROW0() { // assign compatible _Right (assume pointer) reset(_Right.release()); return (*this); } auto_ptr<_Ty>& operator=(auto_ptr<_Ty>& _Right) _THROW0() { // assign compatible _Right (assume pointer) reset(_Right.release()); return (*this); } auto_ptr<_Ty>& operator=(auto_ptr_ref<_Ty> _Right) _THROW0() { // assign compatible _Right._Ref (assume pointer) _Ty **_Pptr = (_Ty **)_Right._Ref; _Ty *_Ptr = *_Pptr; *_Pptr = 0; // release old reset(_Ptr); // set new return (*this); } What is the correct/standard behavior? How do other STL implementations behave?

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• Why does my finite state machine take so long to execute?

  - by BillyONeal

  Hello all :) I'm working on a state machine which is supposed to extract function calls of the form /* I am a comment */ //I am a comment perf("this.is.a.string.which\"can have QUOTES\"", 123456); where the extracted data would be perf("this.is.a.string.which\"can have QUOTES\"", 123456); from a file. Currently, to process a 41kb file, this process is taking close to a minute and a half. Is there something I'm seriously misunderstanding here about this finite state machine? #include <boost/algorithm/string.hpp> std::vector<std::string> Foo() { std::string fileData; //Fill filedata with the contents of a file std::vector<std::string> results; std::string::iterator begin = fileData.begin(); std::string::iterator end = fileData.end(); std::string::iterator stateZeroFoundLocation = fileData.begin(); std::size_t state = 0; for(; begin < end; begin++) { switch (state) { case 0: if (boost::starts_with(boost::make_iterator_range(begin, end), "pref(")) { stateZeroFoundLocation = begin; begin += 4; state = 2; } else if (*begin == '/') state = 1; break; case 1: state = 0; switch (*begin) { case '*': begin = boost::find_first(boost::make_iterator_range(begin, end), "*/").end(); break; case '/': begin = std::find(begin, end, L'\n'); } break; case 2: if (*begin == '"') state = 3; break; case 3: switch(*begin) { case '\\': state = 4; break; case '"': state = 5; } break; case 4: state = 3; break; case 5: if (*begin == ',') state = 6; break; case 6: if (*begin != ' ') state = 7; break; case 7: switch(*begin) { case '"': state = 8; break; default: state = 10; break; } break; case 8: switch(*begin) { case '\\': state = 9; break; case '"': state = 10; } break; case 9: state = 8; break; case 10: if (*begin == ')') state = 11; break; case 11: if (*begin == ';') state = 12; break; case 12: state = 0; results.push_back(std::string(stateZeroFoundLocation, begin)); }; } return results; } Billy3

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• Which function pair in QString to use for converting to/from std::string?

  - by Noah Roberts

  I'm working on a project that we want to use Unicode and could end up in countries like Japan, etc... We want to use std::string for the underlying type that holds string data in the data layer (see Qt, MSVC, and /Zc:wchar_t- == I want to blow up the world as to why). The problem is that I'm not completely sure which function pair (to/from) to use for this and be sure we're 100% compatible with anything the user might enter in the Qt layer. A look at to/fromStdString indicates that I'd have to use setCodecForCStrings. The documentation for that function though indicates that I wouldn't want to do this for things like Japanese. This is the set that I'd LIKE to use though. Does someone know enough to explain how I'd set this up if it's possible? The other option that looks like I could be pretty sure of it working is the to/fromUTF8 functions. Those would require a two step approach though so I'd prefer the other if possible. Is there anything I've missed?

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• What am I doing wrong?, linking in C++

  - by Facon

  I'm trying to code a simple base64 encoder/decoder (to test my programming skill). I can compile it, but it doesn't link, I've this message error: C:\Documents and Settings\Facon\Escritoriog++ base64.o main.o -o prueba.exe main.o:main.cpp:(.text+0x24a): undefined reference to `Base64Encode(std::vector const&)' collect2: ld returned 1 exit status Compiler & Linker: Mingw32 3.4.5 SO: Windows XP This is my source code: base64.h: #ifndef BASE64_H #define BASE64_H #include <iostream> #include <vector> typedef unsigned char byte; std::string Base64Encode(const std::vector<byte> &array); std::vector<byte> Base64Decode(const std::string &array); #endif base64.cpp: #include "base64.h" std::string Base64Encode(std::vector<byte> &array) { const char *base64_table = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"; const unsigned int size = array.size(); std::string output; for (unsigned int i = 0; (i < size); i++) { if ((size - i) > 3) { output.push_back(static_cast<char>(base64_table[array[i] >> 2])); output.push_back(static_cast<char>(base64_table[((array[i++] & 0x03) << 4) | ((array[i] & 0xF0) >> 4)])); output.push_back(static_cast<char>(base64_table[((array[i++] & 0x0F) << 2) | ((array[i] & 0xC0) >> 4)])); output.push_back(static_cast<char>(base64_table[array[i] & 0x3F])); } else if ((size - i) == 3) { output.push_back(static_cast<char>(base64_table[array[i] >> 2])); output.push_back(static_cast<char>(base64_table[((array[i++] & 0x03) << 4) | ((array[i] & 0xF0) >> 4)])); output.push_back(static_cast<char>(base64_table[(array[i] & 0x0F) << 2])); output.push_back(static_cast<char>('=')); } else if ((size - i) == 2) { output.push_back(static_cast<char>(base64_table[array[i] >> 2])); output.push_back(static_cast<char>(base64_table[(array[i] & 0x03) << 4])); output.push_back('='); output.push_back('='); } } return output; } std::vector<byte> Base64Decode(const std::string &array) // TODO { const char *base64_table = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"; } main.cpp: #include <iostream> #include <vector> #include "base64.h" using namespace std; int main(int argc, char *argv[]) { const char* prueba = "sure."; vector<byte> texto; string codificado; for (unsigned int i = 0; (prueba[i] != 0); i++) { texto.push_back(prueba[i]); } codificado = Base64Encode(texto); cout << codificado; return 0; } PD: Sorry for my bad knowledge of English :P

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• Fill container with template parameters

  - by phlipsy

  I want to fill the template parameters passed to a variadic template into an array with fixed length. For that purpose I wrote the following helper function templates template<typename ForwardIterator, typename T> void fill(ForwardIterator i) { } template<typename ForwardIterator, typename T, T head, T... tail> void fill(ForwardIterator i) { *i = head; fill<ForwardIterator, T, tail...>(++i); } the following class template template<typename T, T... args> struct params_to_array; template<typename T, T last> struct params_to_array<T, last> { static const std::size_t SIZE = 1; typedef std::array<T, SIZE> array_type; static const array_type params; private: void init_params() { array_type result; fill<typename array_type::iterator, T, head, tail...>(result.begin()); return result; } }; template<typename T, T head, T... tail> struct params_to_array<T, head, tail...> { static const std::size_t SIZE = params_to_array<T, tail...>::SIZE + 1; typedef std::array<T, SIZE> array_type; static const array_type params; private: void init_params() { array_type result; fill<typename array_type::iterator, T, last>(result.begin()); return result; } }; and initialized the static constants via template<typename T, T last> const typename param_to_array<T, last>::array_type param_to_array<T, last>::params = param_to_array<T, last>::init_params(); and template<typename T, T head, T... tail> const typename param_to_array<T, head, tail...>::array_type param_to_array<T, head, tail...>::params = param_to_array<T, head, tail...>::init_params(); Now the array param_to_array<int, 1, 3, 4>::params is a std::array<int, 3> and contains the values 1, 3 and 4. I think there must be a simpler way to achieve this behavior. Any suggestions? Edit: As Noah Roberts suggested in his answer I modified my program like the following: I wrote a new struct counting the elements in a parameter list: template<typename T, T... args> struct count; template<typename T, T head, T... tail> struct count<T, head, tail...> { static const std::size_t value = count<T, tail...>::value + 1; }; template<typename T, T last> stuct count<T, last> { static const std::size_t value = 1; }; and wrote the following function template<typename T, T... args> std::array<T, count<T, args...>::value> params_to_array() { std::array<T, count<T, args...>::value> result; fill<typename std::array<T, count<T, args...>::value>::iterator, T, args...>(result.begin()); return result; } Now I get with params_to_array<int, 10, 20, 30>() a std::array<int, 3> with the content 10, 20 and 30. Any further suggestions?

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• How to safely operate on parameters in threads, using C++ & Pthreads?

  - by ChrisCphDK

  Hi. I'm having some trouble with a program using pthreads, where occassional crashes occur, that could be related to how the threads operate on data So I have some basic questions about how to program using threads, and memory layout: Assume that a public class function performs some operations on some strings, and returns the result as a string. The prototype of the function could be like this: std::string SomeClass::somefunc(const std::string &strOne, const std::string &strTwo) { //Error checking of strings have been omitted std::string result = strOne.substr(0,5) + strTwo.substr(0,5); return result; } Is it correct to assume that strings, being dynamic, are stored on the heap, but that a reference to the string is allocated on the stack at runtime? Stack: [Some mem addr] pointer address to where the string is on the heap Heap: [Some mem addr] memory allocated for the initial string which may grow or shrink To make the function thread safe, the function is extended with the following mutex (which is declared as private in the "SomeClass") locking: std::string SomeClass::somefunc(const std::string &strOne, const std::string &strTwo) { pthread_mutex_lock(&someclasslock); //Error checking of strings have been omitted std::string result = strOne.substr(0,5) + strTwo.substr(0,5); pthread_mutex_unlock(&someclasslock); return result; } Is this a safe way of locking down the operations being done on the strings (all three), or could a thread be stopped by the scheduler in the following cases, which I'd assume would mess up the intended logic: a. Right after the function is called, and the parameters: strOne & strTwo have been set in the two reference pointers that the function has on the stack, the scheduler takes away processing time for the thread and lets a new thread in, which overwrites the reference pointers to the function, which then again gets stopped by the scheduler, letting the first thread back in? b. Can the same occur with the "result" string: the first string builds the result, unlocks the mutex, but before returning the scheduler lets in another thread which performs all of it's work, overwriting the result etc. Or are the reference parameters / result string being pushed onto the stack while another thread is doing performing it's task? Is the safe / correct way of doing this in threads, and "returning" a result, to pass a reference to a string that will be filled with the result instead: void SomeClass::somefunc(const std::string &strOne, const std::string &strTwo, std::string result) { pthread_mutex_lock(&someclasslock); //Error checking of strings have been omitted result = strOne.substr(0,5) + strTwo.substr(0,5); pthread_mutex_unlock(&someclasslock); } The intended logic is that several objects of the "SomeClass" class creates new threads and passes objects of themselves as parameters, and then calls the function: "someFunc": int SomeClass::startNewThread() { pthread_attr_t attr; pthread_t pThreadID; if(pthread_attr_init(&attr) != 0) return -1; if(pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED) != 0) return -2; if(pthread_create(&pThreadID, &attr, proxyThreadFunc, this) != 0) return -3; if(pthread_attr_destroy(&attr) != 0) return -4; return 0; } void* proxyThreadFunc(void* someClassObjPtr) { return static_cast<SomeClass*> (someClassObjPtr)->somefunc("long string","long string"); } Sorry for the long description. But I hope the questions and intended purpose is clear, if not let me know and I'll elaborate. Best regards. Chris

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• What is a truly empty std::vector in C++?

  - by RyanG

  I've got a two vectors in class A that contain other class objects B and C. I know exactly how many elements these vectors are supposed to hold at maximum. In the initializer list of class A's constructor, I initialize these vectors to their max sizes (constants). If I understand this correctly, I now have a vector of objects of class B that have been initialized using their default constructor. Right? When I wrote this code, I thought this was the only way to deal with things. However, I've since learned about std::vector.reserve() and I'd like to achieve something different. I'd like to allocate memory for these vectors to grow as large as possible because adding to them is controlled by user-input, so I don't want frequent resizings. However, I iterate through this vector many, many times per second and I only currently work on objects I've flagged as "active". To have to check a boolean member of class B/C on ever iteration is silly. I don't want these objects to even BE there for my iterators to see when I run through this list. Is reserving the max space ahead of time and using push_back to add a new object to the vector a solution to this?

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• "undefined reference" error with namespace across multiple files

  - by user1330734

  I've looked at several related posts but no luck with this error. I receive this undefined reference error message below when my namespace exists across multiple files. If I compile only ConsoleTest.cpp with contents of Console.cpp dumped into it the source compiles. I would appreciate any feedback on this issue, thanks in advance. g++ Console.cpp ConsoleTest.cpp -o ConsoleTest.o -Wall /tmp/cc8KfSLh.o: In function `getValueTest()': ConsoleTest.cpp:(.text+0x132): undefined reference to `void Console::getValue<unsigned int>(unsigned int&)' collect2: ld returned 1 exit status Console.h #include <iostream> #include <sstream> #include <string> namespace Console { std::string getLine(); template <typename T> void getValue(T &value); } Console.cpp #include "Console.h" using namespace std; namespace Console { string getLine() { string str; while (true) { cin.clear(); if (cin.eof()) { break; // handle eof (Ctrl-D) gracefully } if (cin.good()) { char next = cin.get(); if (next == '\n') break; str += next; // add character to string } else { cin.clear(); // clear error state string badToken; cin >> badToken; cerr << "Bad input encountered: " << badToken << endl; } } return str; } template <typename T> void getValue(T &value) { string inputStr = Console::getLine(); istringstream strStream(inputStr); strStream >> value; } } ConsoleTest.cpp #include "Console.h" void getLineTest() { std::string str; std::cout << "getLinetest" << std::endl; while (str != "next") { str = Console::getLine(); std::cout << "<string>" << str << "</string>"<< std::endl; } } void getValueTest() { std::cout << "getValueTest" << std::endl; unsigned x = 0; while (x != 12345) { Console::getValue(x); std::cout << "x: " << x << std::endl; } } int main() { getLineTest(); getValueTest(); return 0; }

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• C++: getting the address of the start of an std::vector ?

  - by shoosh

  Sometimes it is useful to use the starting address of an std::vector and temporarily treat that address as the address of a regularly allocated buffer. For instance replace this: char* buf = new char[size]; fillTheBuffer(buf, size); useTheBuffer(buf, size); delete[] buf; With This: vector<char> buf(size); fillTheBuffer(&buf[0], size); useTheBuffer(&buf[0], size); The advantage of this is of course that the buffer is deallocated automatically and I don't have to worry about the delete[]. The problem I'm having with this is when size == 0. In that case the first version works ok. An empty buffer is "allocated" and the subsequent functions do nothing size they get size == 0. The second version however fails if size == 0 since calling buf[0] may rightly contain an assertion that 0 < size. So is there an alternative to the idiom &buf[0] that returns the address of the start of the vector even if the vector is empty? I've also considered using buf.begin() but according to the standard it isn't even guaranteed to return a pointer.

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• Can't build full html table in QTextEdit with std::for_each...

  - by mosg

  Hi. Here is my code function: void ReportHistory::update(void) { ui.output->clear(); ui.output->setCurrentFont(QFont("Arial", 8, QFont::Normal)); QString title = "My Title"; QStringList headers = QString("Header1,Header2,Header3,Header4,Header5,Header6").split(","); QString html = QString( "<html>" \ "<head>" \ "<meta Content=\"Text/html; charset=Windows-1251\">" \ "<title>%1</title>" \ "</head>" \ "<body bgcolor=#ffffff link=#5000A0>" \ "<p>%1</p>" \ "<table border=1 cellspacing=0 cellpadding=2>" \ "<tr bgcolor=#f0f0f0>" ).arg(title); foreach (QString header, headers) { html.append(QString("<th>%1</th>").arg(header)); } html.append("</tr>"); struct Fill { QString html_; Analytics::NavHistory::History::value_type prev_; Fill(QString html) : html_(html) {} void operator ()(const Analytics::NavHistory::History::value_type& entry) { QStringList line = (QString( "%1|%2|%3|%4|%5|%6" ).arg(value1, 15) .arg(value2 ? ' ' : 'C', 8) .arg(value3, 15) .arg(value4, 15, 'f', 4) .arg(value5, 15) .arg(value6, 15, 'f', 4)).split("|"); html_.append("<tr>"); foreach (QString item, line) { html_.append("<td bkcolor=0>%1</td>").arg(item); } html_.append("</tr>"); prev_ = entry; } }; std::for_each(history_->data().begin(), history_->data().end(), Fill(html)); html.append( "</table>" \ "</body>" \ "</html>"); ui.output->setHtml(html); } Where: ui.output is a pointer to QTextEdit. Question: the ui.output just show me the headers, and not the full table, what is wrong? Thanks.

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• C++ floating point precision

  - by Davinel

  double a = 0.3; std::cout.precision(20); std::cout << a << std::endl; result: 0.2999999999999999889 double a, b; a = 0.3; b = 0; for (char i = 1; i <= 50; i++) { b = b + a; }; std::cout.precision(20); std::cout << b << std::endl; result: 15.000000000000014211 So.. 'a' is smaller than it should be. But if we take 'a' 50 times - result will be bigger than it should be. Why is this? And how to get correct result in this case?

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• nested iterator errors

  - by Sean

  //arrayList.h #include<iostream> #include<sstream> #include<string> #include<algorithm> #include<iterator> using namespace std; template<class T> class arrayList{ public: // constructor, copy constructor and destructor arrayList(int initialCapacity = 10); arrayList(const arrayList<T>&); ~arrayList() { delete[] element; } // ADT methods bool empty() const { return listSize == 0; } int size() const { return listSize; } T& get(int theIndex) const; int indexOf(const T& theElement) const; void erase(int theIndex); void insert(int theIndex, const T& theElement); void output(ostream& out) const; // additional method int capacity() const { return arrayLength; } void reverse(); // new defined // iterators to start and end of list class iterator; class seamlessPointer; seamlessPointer begin() { return seamlessPointer(element); } seamlessPointer end() { return seamlessPointer(element + listSize); } // iterator for arrayList class iterator { public: // typedefs required by C++ for a bidirectional iterator typedef bidirectional_iterator_tag iterator_category; typedef T value_type; typedef ptrdiff_t difference_type; typedef T* pointer; typedef T& reference; // constructor iterator(T* thePosition = 0) { position = thePosition; } // dereferencing operators T& operator*() const { return *position; } T* operator->() const { return position; } // increment iterator& operator++() // preincrement { ++position; return *this; } iterator operator++(int) // postincrement { iterator old = *this; ++position; return old; } // decrement iterator& operator--() // predecrement { --position; return *this; } iterator operator--(int) // postdecrement { iterator old = *this; --position; return old; } // equality testing bool operator!=(const iterator right) const { return position != right.position; } bool operator==(const iterator right) const { return position == right.position; } protected: T* position; }; // end of iterator class class seamlessPointer: public arrayList<T>::iterator { // constructor seamlessPointer(T *thePosition) { iterator::position = thePosition; } //arithmetic operators seamlessPointer & operator+(int n) { arrayList<T>::iterator::position += n; return *this; } seamlessPointer & operator+=(int n) { arrayList<T>::iterator::position += n; return *this; } seamlessPointer & operator-(int n) { arrayList<T>::iterator::position -= n; return *this; } seamlessPointer & operator-=(int n) { arrayList<T>::iterator::position -= n; return *this; } T& operator[](int n) { return arrayList<T>::iterator::position[n]; } bool operator<(seamlessPointer &rhs) { if(int(arrayList<T>::iterator::position - rhs.position) < 0) return true; return false; } bool operator<=(seamlessPointer & rhs) { if (int(arrayList<T>::iterator::position - rhs.position) <= 0) return true; return false; } bool operator >(seamlessPointer & rhs) { if (int(arrayList<T>::iterator::position - rhs.position) > 0) return true; return false; } bool operator >=(seamlessPointer &rhs) { if (int(arrayList<T>::iterator::position - rhs.position) >= 0) return true; return false; } }; protected: // additional members of arrayList void checkIndex(int theIndex) const; // throw illegalIndex if theIndex invalid T* element; // 1D array to hold list elements int arrayLength; // capacity of the 1D array int listSize; // number of elements in list }; #endif //main.cpp #include<iostream> #include"arrayList.h" #include<fstream> #include<algorithm> #include<string> using namespace std; bool compare_nocase (string first, string second) { unsigned int i=0; while ( (i<first.length()) && (i<second.length()) ) { if (tolower(first[i])<tolower(second[i])) return true; else if (tolower(first[i])>tolower(second[i])) return false; ++i; } if (first.length()<second.length()) return true; else return false; } int main() { ifstream fin; ofstream fout; string str; arrayList<string> dict; fin.open("dictionary"); if (!fin.good()) { cout << "Unable to open file" << endl; return 1; } int k=0; while(getline(fin,str)) { dict.insert(k,str); // cout<<dict.get(k)<<endl; k++; } //sort the array sort(dict.begin, dict.end(),compare_nocase); fout.open("sortedDictionary"); if (!fout.good()) { cout << "Cannot create file" << endl; return 1; } dict.output(fout); fin.close(); return 0; } Two errors are: ..\src\test.cpp: In function 'int main()': ..\src\test.cpp:50:44: error: no matching function for call to 'sort(<unresolved overloaded function type>, arrayList<std::basic_string<char> >::seamlessPointer, bool (&)(std::string, std::string))' ..\src\/arrayList.h: In member function 'arrayList<T>::seamlessPointer arrayList<T>::end() [with T = std::basic_string<char>]': ..\src\test.cpp:50:28: instantiated from here ..\src\/arrayList.h:114:3: error: 'arrayList<T>::seamlessPointer::seamlessPointer(T*) [with T = std::basic_string<char>]' is private ..\src\/arrayList.h:49:44: error: within this context Why do I get these errors? Update I add public: in the seamlessPointer class and change begin to begin() Then I got the following errors: ..\hw3prob2.cpp:50:46: instantiated from here c:\wascana\mingw\bin\../lib/gcc/mingw32/4.5.0/include/c++/bits/stl_algo.h:5250:4: error: no match for 'operator-' in '__last - __first' ..\/arrayList.h:129:21: note: candidate is: arrayList<T>::seamlessPointer& arrayList<T>::seamlessPointer::operator-(int) [with T = std::basic_string<char>, arrayList<T>::seamlessPointer = arrayList<std::basic_string<char> >::seamlessPointer] c:\wascana\mingw\bin\../lib/gcc/mingw32/4.5.0/include/c++/bits/stl_algo.h:5252:4: instantiated from 'void std::sort(_RAIter, _RAIter, _Compare) [with _RAIter = arrayList<std::basic_string<char> >::seamlessPointer, _Compare = bool (*)(std::basic_string<char>, std::basic_string<char>)]' ..\hw3prob2.cpp:50:46: instantiated from here c:\wascana\mingw\bin\../lib/gcc/mingw32/4.5.0/include/c++/bits/stl_algo.h:2190:7: error: no match for 'operator-' in '__last - __first' ..\/arrayList.h:129:21: note: candidate is: arrayList<T>::seamlessPointer& arrayList<T>::seamlessPointer::operator-(int) [with T = std::basic_string<char>, arrayList<T>::seamlessPointer = arrayList<std::basic_string<char> >::seamlessPointer] Then I add operator -() in the seamlessPointer class ptrdiff_t operator -(seamlessPointer &rhs) { return (arrayList<T>::iterator::position - rhs.position); } Then I compile successfully. But when I run it, I found memeory can not read error. I debug and step into and found the error happens in stl function template<typename _RandomAccessIterator, typename _Distance, typename _Tp, typename _Compare> void __adjust_heap(_RandomAccessIterator __first, _Distance __holeIndex, _Distance __len, _Tp __value, _Compare __comp) { const _Distance __topIndex = __holeIndex; _Distance __secondChild = __holeIndex; while (__secondChild < (__len - 1) / 2) { __secondChild = 2 * (__secondChild + 1); if (__comp(*(__first + __secondChild), *(__first + (__secondChild - 1)))) __secondChild--; *(__first + __holeIndex) = _GLIBCXX_MOVE(*(__first + __secondChild)); ////// stop here __holeIndex = __secondChild; } Of course, there must be something wrong with the customized operators of iterator. Does anyone know the possible reason? Thank you.

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• Error with Phoenix placeholder _val in Boost.Spirit.Lex :(

  - by GooRoo

  Hello, everybody. I'm newbie in Boost.Spirit.Lex. Some strange error appears every time I try to use lex::_val in semantics actions in my simple lexer: #ifndef _TOKENS_H_ #define _TOKENS_H_ #include <iostream> #include <string> #include <boost/spirit/include/lex_lexertl.hpp> #include <boost/spirit/include/phoenix_operator.hpp> #include <boost/spirit/include/phoenix_statement.hpp> #include <boost/spirit/include/phoenix_container.hpp> namespace lex = boost::spirit::lex; namespace phx = boost::phoenix; enum tokenids { ID_IDENTIFICATOR = 1, ID_CONSTANT, ID_OPERATION, ID_BRACKET, ID_WHITESPACES }; template <typename Lexer> struct mega_tokens : lex::lexer<Lexer> { mega_tokens() : identifier(L"[a-zA-Z_][a-zA-Z0-9_]*", ID_IDENTIFICATOR) , constant (L"[0-9]+(\\.[0-9]+)?", ID_CONSTANT ) , operation (L"[\\+\\-\\*/]", ID_OPERATION ) , bracket (L"[\\(\\)\\[\\]]", ID_BRACKET ) { using lex::_tokenid; using lex::_val; using phx::val; this->self = operation [ std::wcout << val(L'<') << _tokenid // << val(L':') << lex::_val << val(L'>') ] | identifier [ std::wcout << val(L'<') << _tokenid << val(L':') << _val << val(L'>') ] | constant [ std::wcout << val(L'<') << _tokenid // << val(L':') << _val << val(L'>') ] | bracket [ std::wcout << phx::val(lex::_val) << val(L'<') << _tokenid // << val(L':') << lex::_val << val(L'>') ] ; } lex::token_def<wchar_t, wchar_t> operation; lex::token_def<std::wstring, wchar_t> identifier; lex::token_def<double, wchar_t> constant; lex::token_def<wchar_t, wchar_t> bracket; }; #endif // _TOKENS_H_ and #include <cstdlib> #include <iostream> #include <locale> #include <boost/spirit/include/lex_lexertl.hpp> #include "tokens.h" int main() { setlocale(LC_ALL, "Russian"); namespace lex = boost::spirit::lex; typedef std::wstring::iterator base_iterator; typedef lex::lexertl::token < base_iterator, boost::mpl::vector<wchar_t, std::wstring, double, wchar_t>, boost::mpl::true_ > token_type; typedef lex::lexertl::actor_lexer<token_type> lexer_type; typedef mega_tokens<lexer_type>::iterator_type iterator_type; mega_tokens<lexer_type> mega_lexer; std::wstring str = L"alfa+x1*(2.836-x2[i])"; base_iterator first = str.begin(); bool r = lex::tokenize(first, str.end(), mega_lexer); if (r) { std::wcout << L"Success" << std::endl; } else { std::wstring rest(first, str.end()); std::wcerr << L"Lexical analysis failed\n" << L"stopped at: \"" << rest << L"\"\n"; } return EXIT_SUCCESS; } This code causes an error in Boost header 'boost/spirit/home/lex/argument.hpp' on line 167 while compiling: return: can't convert 'const boost::variant' to 'boost::variant &' When I don't use lex::_val program compiles with no errors. Obviously, I use _val in wrong way, but I do not know how to do this correctly. Help, please! :) P.S. And sorry for my terrible English…

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• Specialization of template after instantiation?

  - by Onur Cobanoglu

  Hi, My full code is too long, but here is a snippet that will reflect the essence of my problem: class BPCFGParser { public: ... ... class Edge { ... ... }; class ActiveEquivClass { ... ... }; class PassiveEquivClass { ... ... }; struct EqActiveEquivClass { ... ... }; struct EqPassiveEquivClass { ... ... }; unordered_map<ActiveEquivClass, Edge *, hash<ActiveEquivClass>, EqActiveEquivClass> discovered_active_edges; unordered_map<PassiveEquivClass, Edge *, hash<PassiveEquivClass>, EqPassiveEquivClass> discovered_passive_edges; }; namespace std { template <> class hash<BPCFGParser::ActiveEquivClass> { public: size_t operator()(const BPCFGParser::ActiveEquivClass & aec) const { } }; template <> class hash<BPCFGParser::PassiveEquivClass> { public: size_t operator()(const BPCFGParser::PassiveEquivClass & pec) const { } }; } When I compile this code, I get the following errors: In file included from BPCFGParser.cpp:3, from experiments.cpp:2: BPCFGParser.h:408: error: specialization of ‘std::hash<BPCFGParser::ActiveEquivClass>’ after instantiation BPCFGParser.h:408: error: redefinition of ‘class std::hash<BPCFGParser::ActiveEquivClass>’ /usr/include/c++/4.3/tr1_impl/functional_hash.h:44: error: previous definition of ‘class std::hash<BPCFGParser::ActiveEquivClass>’ BPCFGParser.h:445: error: specialization of ‘std::hash<BPCFGParser::PassiveEquivClass>’ after instantiation BPCFGParser.h:445: error: redefinition of ‘class std::hash<BPCFGParser::PassiveEquivClass>’ /usr/include/c++/4.3/tr1_impl/functional_hash.h:44: error: previous definition of ‘class std::hash<BPCFGParser::PassiveEquivClass>’ Now I have to specialize std::hash for these classes (because standard std::hash definition does not include user defined types). When I move these template specializations before the definition of class BPCFGParser, I get a variety of errors for a variety of different things tried, and somewhere (http://www.parashift.com/c++-faq-lite/misc-technical-issues.html) I read that: Whenever you use a class as a template parameter, the declaration of that class must be complete and not simply forward declared. So I'm stuck. I cannot specialize the templates after BPCFGParser definition, I cannot specialize them before BPCFGParser definition, how may I get this working? Thanks in advance, Onur

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• Vim + OmniCppComplete: Completing on Class Members which are STL containers

  - by Robert S. Barnes

  Completion on class members which are STL containers is failing. Completion on local objects which are STL containers works fine. For example, given the following files: // foo.h #include <string> class foo { public: void set_str(const std::string &); std::string get_str_reverse( void ); private: std::string str; }; // foo.cpp #include "foo.h" using std::string; string foo::get_str_reverse ( void ) { string temp; temp.assign(str); reverse(temp.begin(), temp.end()); return temp; } /* ----- end of method foo::get_str ----- */ void foo::set_str ( const string &s ) { str.assign(s); } /* ----- end of method foo::set_str ----- */ I've generated the tags for these two files using: ctags -R --c++-kinds=+pl --fields=+iaS --extra=+q . When I type temp. in the cpp I get a list of string member functions as expected. But if I type str. omnicppcomplete spits out "Pattern Not Found". I've noticed that the temp. completion only works if I have the using std::string; declaration. How do I get completion to work on my class members which are STL containers? Edit I found that completion on members which are STL containers works if I make the follow modifications to the header: // foo.h #include <string> using std::string; class foo { public: void set_str(const string &); string get_str_reverse( void ); private: string str; }; Basically, if I add using std::string; and then remove the std:: name space qualifier from the string str; member and regenerate the tags file then OmniCppComplete is able to do completion on str.. It doesn't seem to matter whether or not I have let OmniCpp_DefaultNamespaces = ["std", "_GLIBCXX_STD"] set in the .vimrc. The problem is that putting using declarations in header files seems like a big no-no, so I'm back to square one.

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• Read and write struct in C

  - by Sergey

  I have a struct: typedef struct student { char fname[30]; char sname[30]; char tname[30]; Faculty fac; int course; char group[10]; int room; int bad; } Student; I read it from the file: Database * dbOpen(char *fname) { FILE *fp = fopen(fname, "rb"); List *lst, *temp; Student *std; Database *db = malloc(sizeof(*db)); if (!fp) return NULL; FileNameS = fname; std = malloc(sizeof(*std)); if (!fread(std, sizeof(*std), 1, fp)) { db->head = db->tail = NULL; return db; } lst = malloc(sizeof(*lst)); lst->s = std; lst->prev = NULL; db->head = lst; while (!feof(fp)) { fread(std, sizeof(*std), 1, fp); temp = malloc(sizeof(*temp)); temp->s = std; temp->prev = lst; lst->next = temp; lst = temp; } lst->next = NULL; db->tail = lst; fclose(fp); return db; } And I have a problem... At the last record i have a such file pointer: `fp 0x10311448 {_ptr=0x00344b90 "???????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????? _ _iobuf * ` And i read last record 2 times... Save file code: void * dbClose(Database *db) { FILE *fp = fopen(FileNameS, "w+b"); List *lst, *temp; lst = db->head; while(lst != NULL) { fwrite(lst->s, sizeof(*(lst->s)), 1, fp); temp = lst; lst = lst->next; free(temp); } free(db); fclose(fp); }

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• Help with these warnings. [inheritance].

  - by sil3nt

  Hello there. I have a set of code, which mimics a basic library cataloging system. There is a base class named items, in which the the general id,title and year variables are defined and 3 other derived classes (DVD,Book and CD). Base [Items] Derived [DVD,Book,CD]. The programs runs, however I get the following warnings, I'm not sure how to fix these. "C:\Program Files\gcc\bin/g++" -Os -mconsole -g -Wall -Wshadow -fno-common mainA4.cpp -o mainA4.exe In file included from mainA4.cpp:5: a4.h: In constructor `DVD::DVD(int, std::string, int, std::string)': a4.h:28: warning: `DVD::director' will be initialized after a4.h:32: warning: base `Items' a4.h:32: warning: when initialized here a4.h: In constructor `Book::Book(int, std::string, int, std::string, int)': a4.h:48: warning: `Book::numPages' will be initialized after a4.h:52: warning: base `Items' a4.h:52: warning: when initialized here a4.h: In constructor `CD::CD(int, std::string, int, std::string, int)': a4.h:66: warning: `CD::numSongs' will be initialized after a4.h:70: warning: base `Items' a4.h:70: warning: when initialized here Exit code: 0

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• Removing a character from a string

  - by Prasanth Madhavan

  i have a string. I want to delete the last character of the string if it is a space. i tried the following code, str.erase(remove_if(str.begin(), str.end(), isspace), str.end()); but my g++ compiler gives me an error saying: error: no matching function for call to ‘remove_if(__gnu_cxx::__normal_iterator<char*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, __gnu_cxx::__normal_iterator<char*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, <unresolved overloaded function type>)’ please help.

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• Is there a standard Cyclic Iterator in C++

  - by Hippicoder

  Based on the following question: Check if one string is a rotation of other string I was thinking of making a cyclic iterator type that takes a range, and would be able to solve the above problem like so: std::string s1 = "abc" ; std::string s2 = "bca" ; std::size_t n = 2; // number of cycles cyclic_iterator it(s2.begin(),s2.end(),n); cyclic_iterator end; if (std::search(it, end, s1.begin(),s1.end()) != end) { std::cout << "s1 is a rotation of s2" << std::endl; } My question, Is there already something like this available? I've check Boost and STL doesn't have one. I've got a simple hand-written one but would rather use an already made/tested implementation.

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• OpenGL textures trigger error 1281 and strange background behavior

  - by user3714670

  I am using SOIL to apply textures to VBOs, without textures i could change the background and display black (default color) vbos easily, but now with textures, openGL is giving an error 1281, the background is black and some textures are not applied. There must be something i didn't understand about applying/loading the textures. BUt the texture IS applied (nothing else is working though), the error is applied when i try to use the shader program however i checked the compilation of these and no problems were written. Here is the code i use to load textures, once loaded it is kept in memory, it mostly comes from the example of SOIL : texture = SOIL_load_OGL_single_cubemap( filename, SOIL_DDS_CUBEMAP_FACE_ORDER, SOIL_LOAD_AUTO, SOIL_CREATE_NEW_ID, SOIL_FLAG_POWER_OF_TWO | SOIL_FLAG_MIPMAPS | SOIL_FLAG_DDS_LOAD_DIRECT ); if( texture > 0 ) { glEnable( GL_TEXTURE_CUBE_MAP ); glEnable( GL_TEXTURE_GEN_S ); glEnable( GL_TEXTURE_GEN_T ); glEnable( GL_TEXTURE_GEN_R ); glTexGeni( GL_S, GL_TEXTURE_GEN_MODE, GL_REFLECTION_MAP ); glTexGeni( GL_T, GL_TEXTURE_GEN_MODE, GL_REFLECTION_MAP ); glTexGeni( GL_R, GL_TEXTURE_GEN_MODE, GL_REFLECTION_MAP ); glBindTexture( GL_TEXTURE_CUBE_MAP, texture ); std::cout << "the loaded single cube map ID was " << texture << std::endl; } else { std::cout << "Attempting to load as a HDR texture" << std::endl; texture = SOIL_load_OGL_HDR_texture( filename, SOIL_HDR_RGBdivA2, 0, SOIL_CREATE_NEW_ID, SOIL_FLAG_POWER_OF_TWO | SOIL_FLAG_MIPMAPS ); if( texture < 1 ) { std::cout << "Attempting to load as a simple 2D texture" << std::endl; texture = SOIL_load_OGL_texture( filename, SOIL_LOAD_AUTO, SOIL_CREATE_NEW_ID, SOIL_FLAG_POWER_OF_TWO | SOIL_FLAG_MIPMAPS | SOIL_FLAG_DDS_LOAD_DIRECT ); } if( texture > 0 ) { // enable texturing glEnable( GL_TEXTURE_2D ); // bind an OpenGL texture ID glBindTexture( GL_TEXTURE_2D, texture ); std::cout << "the loaded texture ID was " << texture << std::endl; } else { glDisable( GL_TEXTURE_2D ); std::cout << "Texture loading failed: '" << SOIL_last_result() << "'" << std::endl; } } and how i apply it when drawing : GLuint TextureID = glGetUniformLocation(shaderProgram, "myTextureSampler"); if(!TextureID) cout << "TextureID not found ..." << endl; // glEnableVertexAttribArray(TextureID); glActiveTexture(GL_TEXTURE0); if(SFML) sf::Texture::bind(sfml_texture); else { glBindTexture (GL_TEXTURE_2D, texture); // glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, 1024, 768, 0, GL_RGB, GL_UNSIGNED_BYTE, &texture); } glUniform1i(TextureID, 0); I am not sure that SOIL is adapted to my program as i want something as simple as possible (i used sfml's texture object which was the best but i can't anymore), but if i can get it to work it would be great. EDIT : After narrowing the code implied by the error, here is the code that provokes it, it is called between texture loading and bos drawing : glEnableClientState(GL_VERTEX_ARRAY); //this gives the error : glUseProgram(this->shaderProgram); if (!shaderLoaded) { std::cout << "Loading default shaders" << std::endl; if(textured) loadShaderProgramm(texture_vertexSource, texture_fragmentSource); else loadShaderProgramm(default_vertexSource,default_fragmentSource); } glm::mat4 Projection = camera->getPerspective(); glm::mat4 View = camera->getView(); glm::mat4 Model = glm::mat4(1.0f); Model[0][0] *= scale_x; Model[1][1] *= scale_y; Model[2][2] *= scale_z; glm::vec3 translate_vec(this->x,this->y,this->z); glm::mat4 object_transform = glm::translate(glm::mat4(1.0f),translate_vec); glm::quat rotation = QAccumulative.getQuat(); glm::mat4 matrix_rotation = glm::mat4_cast(rotation); object_transform *= matrix_rotation; Model *= object_transform; glm::mat4 MVP = Projection * View * Model; GLuint ModelID = glGetUniformLocation(this->shaderProgram, "M"); if(ModelID ==-1) cout << "ModelID not found ..." << endl; GLuint MatrixID = glGetUniformLocation(this->shaderProgram, "MVP"); if(MatrixID ==-1) cout << "MatrixID not found ..." << endl; GLuint ViewID = glGetUniformLocation(this->shaderProgram, "V"); if(ViewID ==-1) cout << "ViewID not found ..." << endl; glUniformMatrix4fv(MatrixID, 1, GL_FALSE, &MVP[0][0]); glUniformMatrix4fv(ModelID, 1, GL_FALSE, &Model[0][0]); glUniformMatrix4fv(ViewID, 1, GL_FALSE, &View[0][0]); drawObject();

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• What is the best way to create related types at runtime?

  - by SniperSmiley

  How do I determine the type of a class that is related to another class at runtime? I have figured out a solution, the only problem is that I ended up having to use a define that has to be used in all of the derived classes. Is there a simpler way to do this that doesn't need the define or a copy paste? Things to note: both the class and the related class will always have their respective base class, the different classes can share a related class, and as in the example I would like the control class to own the view. #include <iostream> #include <string> class model; class view { public: view( model *m ) {} virtual std::string display() { return "view"; } }; #define RELATED_CLASS(RELATED)\ typedef RELATED relatedType;\ virtual relatedType*createRelated(){\ return new relatedType(this);} class model { public: RELATED_CLASS(view) model() {} }; class otherView : public view { public: otherView( model *m ) : view(m) {} std::string display() { return "otherView"; } }; class otherModel : public model { public: RELATED_CLASS(otherView) otherModel() {} }; class control { public: control( model *m ) : m_(m), v_( m->createRelated() ) {} ~control() { delete v_; } std::string display() { return v_->display(); } model *m_; view *v_; }; int main( void ) { model m; otherModel om; model *pm = &om; control c1( &m ); control c2( &om ); control c3( pm ); std::cout << c1.display() << std::endl; std::cout << c2.display() << std::endl; std::cout << c3.display() << std::endl; }

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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++ interface inheritance problem

  - by james t

  Hey, i'm trying to create a c++ stomp client, my client constructor is : Client(std::string &server, short port, std::string &login, std::string &pass, Listener &listener); it gets a listener object which when Listener is the following interface : class Listener { virtual void message(StmpMessage message) =0; }; now i attempt to instantiate a client in a test class : class test : public virtual Listener { public: void message(StmpMessage message) { message.prettyPrint(); } int main(int argc, char* argv[]) { Client client("127.0.0.1", 61613, *this); return 0; } }; i'm sending this to the client because this is a listener object, i get the following error : /Users/mzruya/Documents/STOMPCPP/main.cpp:18: error: no matching function for call to 'Client::Client(const char [10], int, test&)' /Users/mzruya/Documents/STOMPCPP/Client.h:43: note: candidates are: Client::Client(std::string&, short int, std::string&, std::string&, Listener&) /Users/mzruya/Documents/STOMPCPP/Client.h:37: note: Client::Client(const Client&)

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• boost.asio error on read from socket.

  - by niXman

  The following code of the client: typedef boost::array<char, 10> header_packet; header_packet header; boost::system::error_code error; ... /** send header */ boost::asio::write( _socket, boost::asio::buffer(header, header.size()), boost::asio::transfer_all(), error ); /** send body */ boost::asio::write( _socket, boost::asio::buffer(buffer, buffer.length()), boost::asio::transfer_all(), error ); of the server: struct header { boost::uint32_t header_length; boost::uint32_t id; boost::uint32_t body_length; }; static header unpack_header(const header_packet& data) { header hdr; sscanf(data.data(), "%02d%04d%04d", &hdr.header_length, &hdr.id, &hdr.body_length); return hdr; } void connection::start() { boost::asio::async_read( _socket, boost::asio::buffer(_header, _header.size()), boost::bind( &connection::read_header_handler, shared_from_this(), boost::asio::placeholders::error ) ); } /***************************************************************************/ void connection::read_header_handler(const boost::system::error_code& e) { if ( !e ) { std::cout << "readed header: " << _header.c_array() << std::endl; std::cout << constants::unpack_header(_header); boost::asio::async_read( _socket, boost::asio::buffer(_body, constants::unpack_header(_header).body_length), boost::bind( &connection::read_body_handler, shared_from_this(), boost::asio::placeholders::error ) ); } else { /** report error */ std::cout << "read header finished with error: " << e.message() << std::endl; } } /***************************************************************************/ void connection::read_body_handler(const boost::system::error_code& e) { if ( !e ) { std::cout << "readed body: " << _body.c_array() << std::endl; start(); } else { /** report error */ std::cout << "read body finished with error: " << e.message() << std::endl; } } On the server side the method read_header_handler() is called, but the method read_body_handler() is never called. Though the client has written down the data in a socket. The header is readed and decoded successfully. What's the error?

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