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  • Triangles in a C++ STL Vector as an Objective-C member sometimes draws incorrectly in OpenGL ES

    - by Rahil627
    The polygons draw correctly 80% of the time. When it fails, a vertex is dislocated. The polygon is consistently drawn with the wrong vertex. I checked that the vector is correct during initialization, even when it's wrongly drawn. I'm using Cocos2d. The class member: @interface Polygon : CCSprite { std::vector<float> triangleVertices; } The draw function called in [Polygon draw]: + (void)drawTrianglesWithVertices:(const std::vector<float> &)v { //glEnableClientState(GL_VERTEX_ARRAY); glDisable(GL_TEXTURE_2D); glDisableClientState(GL_TEXTURE_COORD_ARRAY); glDisableClientState(GL_COLOR_ARRAY); glVertexPointer(2, GL_FLOAT, 0, &v[0]); glDrawArrays(GL_TRIANGLES, 0, v.size()); //glDisableClientState(GL_VERTEX_ARRAY); glEnableClientState(GL_COLOR_ARRAY); glEnableClientState(GL_TEXTURE_COORD_ARRAY); glEnable(GL_TEXTURE_2D); } Any ideas?

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  • How can I change the precision of printing with the stl?

    - by mmr
    This might be a repeat, but my google-fu failed to find it. I want to print numbers to a file using the stl with the number of decimal places, rather than overall precision. So, if I do this: int precision = 16; std::vector<double> thePoint(3); thePoint[0] = 86.3671436; thePoint[0] = -334.8866574; thePoint[0] = 24.2814; ofstream file1(tempFileName, ios::trunc); file1 << std::setprecision(precision) << thePoint[0] << "\\" << thePoint[1] << "\\" << thePoint[2] << "\\"; I'll get numbers like this: 86.36714359999999\-334.8866574\24.28140258789063 What I want is this: 86.37\-334.89\24.28 In other words, truncating at two decimal points. If I set precision to be 4, then I'll get 86.37\-334.9\24.28 ie, the second number is improperly truncated. I do not want to have to manipulate each number explicitly to get the truncation, especially because I seem to be getting the occasional 9 repeating or 0000000001 or something like that that's left behind. I'm sure there's something obvious, like using the printf(%.2f) or something like that, but I'm unsure how to mix that with the stl << and ofstream.

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  • Is there an Objective-C algorithm like `transform` of the C++ STL?

    - by pesche
    My goal is to have an array that contains all filenames of a specific extension, but without the extension. There's an elegant solution to get all filenames of a specific extension using a predicate filter and instructions on how to split a path into filename and extension, but to combine them I would have to write a loop (not terrible, but not elegant either). Is there a way with Objective-C (may be similar to the predicate mechanism) to apply some function to every element of an array and put the results in a second array, like the transform algorithm of the C++ STL does?

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  • How to use c++0x thread in Android NDK?

    - by m-ric
    I am trying to compile this simple program with android-ndk-r8b: jni/hello_jni.cpp #include <iostream> #include <thread> void hello() { std::cout << "Hi i'm a thread!!!" << std::endl; } int main() { std::thread th(hello); th.join(); return 0; } jni/Application.mk APP_OPTIM := release APP_MODULES := hello_thread APP_STL := gnustl_static jni/Android.mk LOCAL_PATH := $(call my-dir) include $(CLEAR_VARS) LOCAL_CPPFLAGS += -std=c++0x -frtti LOCAL_MODULE := hello_thread LOCAL_LDLIBS := -L$(SYSROOT)/usr/lib -pthread LOCAL_SRC_FILES := hello_thread.cpp include $(BUILD_EXECUTABLE) ndk-build returns me an error arguin that 'thread' is not a member of 'std'. I issued ndk-build -n to get the compilation command and issued it alone in my shell: /home/evigier/android-ndk-r8b/toolchains/arm-linux-androideabi-4.6/prebuilt/linux-x86/bin/arm-linux-androideabi-g++ -MMD -MP -MF /home/evigier/eclipse_workspace/hello_thread/obj/local/armeabi/objs/hello_thread/hello_thread.o.d -fpic -ffunction-sections -funwind-tables -fstack-protector -D__ARM_ARCH_5__ -D__ARM_ARCH_5T__ -D__ARM_ARCH_5E__ -D__ARM_ARCH_5TE__ -march=armv5te -mtune=xscale -msoft-float -fno-exceptions -fno-rtti -mthumb -Os -fomit-frame-pointer -fno-strict-aliasing -finline-limit=64 -I/home/evigier/android-ndk-r8b/sources/cxx-stl/gnu-libstdc++/4.6/include -I/home/evigier/android-ndk-r8b/sources/cxx-stl/gnu-libstdc++/4.6/libs/armeabi/include -I/home/evigier/eclipse_workspace/hello_thread/jni -DANDROID -Wa,--noexecstack -std=c++0x -frtti -O2 -DNDEBUG -g -I/home/evigier/android-ndk-r8b/platforms/android-14/arch-arm/usr/include -c /home/evigier/eclipse_workspace/hello_thread/jni/hello_thread.cpp -o /home/evigier/eclipse_workspace/hello_thread/obj/local/armeabi/objs/hello_thread/hello_thread.o Compile++ thumb : hello_thread <= hello_thread.cpp In file included from /home/evigier/android-ndk-r8b/platforms/android-14/arch-arm/usr/include/stdio.h:55:0, from /home/evigier/android-ndk-r8b/platforms/android-14/arch-arm/usr/include/wchar.h:33, from /home/evigier/android-ndk-r8b/sources/cxx-stl/gnu-libstdc++/4.6/include/cwchar:46, from /home/evigier/android-ndk-r8b/sources/cxx-stl/gnu-libstdc++/4.6/include/bits/postypes.h:42, from /home/evigier/android-ndk-r8b/sources/cxx-stl/gnu-libstdc++/4.6/include/iosfwd:42, from /home/evigier/android-ndk-r8b/sources/cxx-stl/gnu-libstdc++/4.6/include/ios:39, from /home/evigier/android-ndk-r8b/sources/cxx-stl/gnu-libstdc++/4.6/include/ostream:40, from /home/evigier/android-ndk-r8b/sources/cxx-stl/gnu-libstdc++/4.6/include/iostream:40, from jni/hello_thread.cpp:4: /home/evigier/android-ndk-r8b/platforms/android-14/arch-arm/usr/include/sys/types.h:124:9: error: 'uint64_t' does not name a type /home/evigier/eclipse_workspace/hello_thread/jni/hello_thread.cpp: In function 'int main()': /home/evigier/eclipse_workspace/hello_thread/jni/hello_thread.cpp:14:5: error: 'thread' is not a member of 'std' /home/evigier/eclipse_workspace/hello_thread/jni/hello_thread.cpp:14:17: error: expected ';' before 'th' /home/evigier/eclipse_workspace/hello_thread/jni/hello_thread.cpp:15:5: error: 'th' was not declared in this scope I read a lot of threads/questions about POSIX threads and C++ threads, but still cannot find my answer. My arm-linux-androideabi/include/c++/4.6/thread file defines class thread in std only: #if defined(_GLIBCXX_HAS_GTHREADS) && defined(_GLIBCXX_USE_C99_STDINT_TR1) They don't seem to be defined in my sdk (c++config.h). But how can I possibly turn them on safely? Do i need to compile my own toolchain to use (non-p)threads? My host computer is : Linux evigier-ThinkPad-X220 3.0.0-17-generic #30-Ubuntu SMP Thu Mar 8 20:45:39 UTC 2012 x86_64 x86_64 x86_64 GNU/Linux

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  • Access Violation When Accessing an STL Object Through A Pointer or Reference In A Different DLL or E

    - by Yan Cheng CHEOK
    I experience the following problem while using legacy VC6. I just cann't switch to modern compiler, as I am working on a legacy code base. http://support.microsoft.com/kb/172396 Since there are no way to export map, my planned workaround is using static linking instead of dynamic linking. I was wondering whether you all had encountered the similar situation? What is your workaround for this? Another workaround is to create wrapper class around the stl map, to ensure creation and accessing stl map, are within the same DLL space. Note that, fun0, which uses wrapper class will just work fine. fun1 will crash. Here is the code example : // main.cpp. Compiled it as exe. #pragma warning (disable : 4786) #include <map> #include <string> template <class K, class V> class __declspec(dllimport) map_wrapper { public: map_wrapper(); ~map_wrapper(); map_wrapper(const map_wrapper&); map_wrapper& operator=(const map_wrapper&); V& operator[](const K&); const V& operator[](const K&) const; const V& get(const K&) const; void put(const K&, const V&); int size() const; private: std::map<K, V> *m; }; __declspec(dllimport) void fun0(map_wrapper<std::string, int>& m); __declspec(dllimport) void fun1(std::map<std::string, int>& m); int main () { map_wrapper<std::string, int> m0; std::map<std::string, int> m1; m0["hello"] = 888; m1["hello"] = 888; // Safe. The we create std::map and access map both in dll space. fun0(m0); // Crash! The we create std::map in exe space, and access map in dll space. fun1(m1); return 0; } // dll.cpp. Compiled it as dynamic dll. #pragma warning (disable : 4786) #include <map> #include <string> #include <iostream> /* In map_wrapper.h */ template <class K, class V> class __declspec(dllexport) map_wrapper { public: map_wrapper(); ~map_wrapper(); map_wrapper(const map_wrapper&); map_wrapper& operator=(const map_wrapper&); V& operator[](const K&); const V& operator[](const K&) const; const V& get(const K&) const; void put(const K&, const V&); int size() const; private: std::map<K, V> *m; }; /* End */ /* In map_wrapper.cpp */ template <class K, class V> map_wrapper<K, V>::map_wrapper() : m(new std::map<K, V>()) { } template <class K, class V> map_wrapper<K, V>::~map_wrapper() { delete m; } template <class K, class V> map_wrapper<K, V>::map_wrapper(const map_wrapper<K, V>& map) : m(new std::map<K, V>(*(map.m))) { } template <class K, class V> map_wrapper<K, V>& map_wrapper<K, V>::operator=(const map_wrapper<K, V>& map) { std::map<K, V>* tmp = this->m; this->m = new std::map<K, V>(*(map.m)); delete tmp; return *this; } template <class K, class V> V& map_wrapper<K, V>::operator[](const K& key) { return (*this->m)[key]; } template <class K, class V> const V& map_wrapper<K, V>::operator[](const K& key) const { return (*this->m)[key]; } template <class K, class V> const V& map_wrapper<K, V>::get(const K& key) const { return (*this->m)[key]; } template <class K, class V> void map_wrapper<K, V>::put(const K& key, const V& value) { (*this->m)[key] = value; } template <class K, class V> int map_wrapper<K, V>::size() const { return this->m->size(); } // See : http://www.parashift.com/c++-faq-lite/templates.html#faq-35.15 // [35.15] How can I avoid linker errors with my template classes? template class __declspec(dllexport) map_wrapper<std::string, int>; /* End */ __declspec(dllexport) void fun0(map_wrapper<std::string, int>& m) { std::cout << m["hello"] << std::endl; } __declspec(dllexport) void fun1(std::map<std::string, int>& m) { std::cout << m["hello"] << std::endl; }

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  • How might I wrap the FindXFile-style APIs to the STL-style Iterator Pattern in C++?

    - by BillyONeal
    Hello everyone :) I'm working on wrapping up the ugly innards of the FindFirstFile/FindNextFile loop (though my question applies to other similar APIs, such as RegEnumKeyEx or RegEnumValue, etc.) inside iterators that work in a manner similar to the Standard Template Library's istream_iterators. I have two problems here. The first is with the termination condition of most "foreach" style loops. STL style iterators typically use operator!= inside the exit condition of the for, i.e. std::vector<int> test; for(std::vector<int>::iterator it = test.begin(); it != test.end(); it++) { //Do stuff } My problem is I'm unsure how to implement operator!= with such a directory enumeration, because I do not know when the enumeration is complete until I've actually finished with it. I have sort of a hack together solution in place now that enumerates the entire directory at once, where each iterator simply tracks a reference counted vector, but this seems like a kludge which can be done a better way. The second problem I have is that there are multiple pieces of data returned by the FindXFile APIs. For that reason, there's no obvious way to overload operator* as required for iterator semantics. When I overload that item, do I return the file name? The size? The modified date? How might I convey the multiple pieces of data to which such an iterator must refer to later in an ideomatic way? I've tried ripping off the C# style MoveNext design but I'm concerned about not following the standard idioms here. class SomeIterator { public: bool next(); //Advances the iterator and returns true if successful, false if the iterator is at the end. std::wstring fileName() const; //other kinds of data.... }; EDIT: And the caller would look like: SomeIterator x = ??; //Construct somehow while(x.next()) { //Do stuff } Thanks! Billy3

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  • [Qt] How to get rid of OCI.dll dependency when compiling static

    - by STL
    Hi, My application accesses an Oracle database through Qt's QSqlDatabase class. I'm compiling Qt as static for the release build, but I can't seem to be able to get rid of OCI.dll dependency. I'm trying to link against oci.lib (as available in Oracle's Instant Client with SDK). Here's my configure line : configure -qt-libjpeg -qt-zlib -qt-libpng -nomake examples -nomake demos -no-exceptions -no-stl -no-rtti -no-qt3support -no-scripttools -no-openssl -no-opengl -no-phonon -no-style-motif -no-style-cde -no-style-cleanlooks -no-style-plastique -static -release -opensource -plugin-sql-oci -plugin-sql-sqlite -platform win32-msvc2005 I link against oci.h and oci.lib in the SDK's folder by using : set INCLUDE=C:\oracle\instantclient\sdk\include;%INCLUDE% set LIB=C:\oracle\instantclient\sdk\lib\msvc;%LIB% Then, once Qt is compiled, I use the following lines in my *.pro file : QT += sql CONFIG += static LIBS += C:\oracle\instantclient\sdk\lib\msvc\oci.lib QTPLUGIN += qsqloci Then, in my main.cpp, I add the following commands to statically compile OCI plugin in the application : #include <QtPlugin> Q_IMPORT_PLUGIN(qsqloci) After compiling the project, I test it on my workstation and it works (as I have Oracle Instant Client installed). When I try on another workstation, I always get the message: This application has failed to start because OCI.dll was not found. Re-installing this application may fix this problem. I don't understand why I still need OCI.dll, as my statically linked application is supposed to link to oci.lib instead. Is there any Qt people here that might have a solution for me ? Thanks a lot ! STL

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  • Is it Bad Practice to use C++ only for the STL containers?

    - by gmatt
    First a little background ... In what follows, I use C,C++ and Java for coding (general) algorithms, not gui's and fancy program's with interfaces, but simple command line algorithms and libraries. I started out learning about programming in Java. I got pretty good with Java and I learned to use the Java containers a lot as they tend to reduce complexity of book keeping while guaranteeing great performance. I intermittently used C++, but I was definitely not as good with it as with Java and it felt cumbersome. I did not know C++ enough to work in it without having to look up every single function and so I quickly reverted back to sticking to Java as much as possible. I then made a sudden transition into cracking and hacking in assembly language, because I felt I was concentrated too much attention on a much too high level language and I needed more experience with how a CPU interacts with memory and whats really going on with the 1's and 0's. I have to admit this was one of the most educational and fun experiences I've had with computers to date. For obviously reasons, I could not use assembly language to code on a daily basis, it was mostly reserved for fun diversions. After learning more about the computer through this experience I then realized that C++ is so much closer to the "level of 1's and 0's" than Java was, but I still felt it to be incredibly obtuse, like a swiss army knife with far too many gizmos to do any one task with elegance. I decided to give plain vanilla C a try, and I quickly fell in love. It was a happy medium between simplicity and enough "micromanagent" to not abstract what is really going on. However, I did miss one thing about Java: the containers. In particular, a simple container (like the stl vector) that expands dynamically in size is incredibly useful, but quite a pain to have to implement in C every time. Hence my code currently looks like almost entirely C with containers from C++ thrown in, the only feature I use from C++. I'd like to know if its consider okay in practice to use just one feature of C++, and ignore the rest in favor of C type code?

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  • 47 memory leaks. STL pointers.

    - by icelated
    I have a major amount of memory leaks. I know that the Sets have pointers and i cannot change that! I cannot change anything, but clean up the mess i have... I am creating memory with new in just about every function to add information to the sets. I have a Cd/ DVD/book: super classes of ITEM class and a library class.. In the library class i have 2 functions for cleaning up the sets.. Also, the CD, DVD, book destructors are not being called.. here is my potential leaks.. library.h #pragma once #include <ostream> #include <map> #include <set> #include <string> #include "Item.h" using namespace std; typedef set<Item*> ItemSet; typedef map<string,Item*> ItemMap; typedef map<string,ItemSet*> ItemSetMap; class Library { public: // general functions void addKeywordForItem(const Item* const item, const string& keyword); const ItemSet* itemsForKeyword(const string& keyword) const; void printItem(ostream& out, const Item* const item) const; // book-related functions const Item* addBook(const string& title, const string& author, int const nPages); const ItemSet* booksByAuthor(const string& author) const; const ItemSet* books() const; // music-related functions const Item* addMusicCD(const string& title, const string& band, const int nSongs); void addBandMember(const Item* const musicCD, const string& member); const ItemSet* musicByBand(const string& band) const; const ItemSet* musicByMusician(const string& musician) const; const ItemSet* musicCDs() const; // movie-related functions const Item* addMovieDVD(const string& title, const string& director, const int nScenes); void addCastMember(const Item* const movie, const string& member); const ItemSet* moviesByDirector(const string& director) const; const ItemSet* moviesByActor(const string& actor) const; const ItemSet* movies() const; ~Library(); void Purge(ItemSet &set); void Purge(ItemSetMap &map); }; here is some functions for adding info using new in library. Keep in mind i am cutting out alot of code to keep this post short. library.cpp #include "Library.h" #include "book.h" #include "cd.h" #include "dvd.h" #include <iostream> // general functions ItemSet allBooks; ItemSet allCDS; ItemSet allDVDs; ItemSetMap allBooksByAuthor; ItemSetMap allmoviesByDirector; ItemSetMap allmoviesByActor; ItemSetMap allMusicByBand; ItemSetMap allMusicByMusician; const ItemSet* Library::itemsForKeyword(const string& keyword) const { const StringSet* kw; ItemSet* obj = new ItemSet(); return obj; const Item* Library::addBook(const string& title, const string& author, const int nPages) { ItemSet* obj = new ItemSet(); Book* item = new Book(title,author,nPages); allBooks.insert(item); // add to set of all books obj->insert(item); return item; const Item* Library::addMusicCD(const string& title, const string& band, const int nSongs) { ItemSet* obj = new ItemSet(); CD* item = new CD(title,band,nSongs); return item; void Library::addBandMember(const Item* musicCD, const string& member) { ItemSet* obj = new ItemSet(); (((CD*) musicCD)->addBandMember(member)); obj->insert((CD*) musicCD); here is the library destructor..... Library::~Library() { Purge(allBooks); Purge(allCDS); Purge(allDVDs); Purge(allBooksByAuthor); Purge(allmoviesByDirector); Purge(allmoviesByActor); Purge(allMusicByBand); Purge(allMusicByMusician); } void Library::Purge(ItemSet &set) { for (ItemSet::iterator it = set.begin(); it != set.end(); ++it) delete *it; set.clear(); } void Library::Purge(ItemSetMap &map) { for (ItemSetMap::iterator it = map.begin(); it != map.end(); ++it) delete it->second; map.clear(); } so, basically item, cd, dvd class all have a set like this: typedef set<string> StringSet; class CD : public Item StringSet* music; and i am deleting it like: but those superclasses are not being called.. Item destructor is. CD::~CD() { delete music; } Do, i need a copy constructor? and how do i delete those objects i am creating in the library class? and how can i get the cd,dvd, destructor called? would the addbandmember function located in the library.cpp cause me to have a copy constructor? Any real help you can provide me to help me clean up this mess instead of telling me not to use pointers in my sets i would really appreciate. How can i delete the memory i am creating in those functions? I cannot delete them in the function!!

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  • How can I use STL sort in c++ to sort some values in the class?

    - by Morteza M.
    I have a class named Graph, in this class I have a member named V, it is a vector. I have a struct named Edge, and a list of Edges. like below: struct Edge{ int u; int v; Edge(int u,int v){ this-u=u; this-v=v; } }; class Graph{ vector < Vertex > V; . . . int edgeCmp(Edge* x,Edge* y){ return (V[x-v].dv].d)?1:0; } void someFunction(){ list backEdges; backEdges.sort(&Graph::edgeCmp); } } But it doesn't work!! may someone help me to do such a thing?

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  • Suggestions on error handling of Win32 C++ code: AtlThrow vs. STL exceptions

    - by EmbeddedProg
    In writing Win32 C++ code, I'd appreciate some hints on how to handle errors of Win32 APIs. In particular, in case of a failure of a Win32 function call (e.g. MapViewOfFile), is it better to: use AtlThrowLastWin32 define a Win32Exception class derived from std::exception, with an added HRESULT data member to store the HRESULT corresponding to value returned by GetLastError? In this latter case, I could use the what() method to return a detailed error string (e.g. "MapViewOfFile call failed in MyClass::DoSomething() method."). What are the pros and cons of 1 vs. 2? Is there any other better option that I am missing? As a side note, if I'd like to localize the component I'm developing, how could I localize the exception what() string? I was thinking of building a table mapping the original English string returned by what() into a Unicode localized error string. Could anyone suggest a better approach? Thanks much for your insights and suggestions.

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  • Writing my own implementation of stl-like Iterator in C++.

    - by Negai
    Good evening everybody, I'm currently trying to understand the intrinsics of iterators in various languages i.e. the way they are implemented. For example, there is the following class exposing the list interface. template<class T> class List { public: virtual void Insert( int beforeIndex, const T item ) throw( ListException ) =0 ; virtual void Append( const T item ) =0; virtual T Get( int position ) const throw( ListException ) =0; virtual int GetLength() const =0; virtual void Remove( int position ) throw( ListException ) =0; virtual ~List() =0 {}; }; According to GoF, the best way to implement an iterator that can support different kinds of traversal is to create the base Iterator class (friend of List) with protected methods that can access List's members. The concrete implementations of Iterator will handle the job in different ways and access List's private and protected data through the base interface. From here forth things are getting confusing. Say, I have class LinkedList and ArrayList, both derived from List, and there are also corresponding iterators, each of the classes returns. How can I implement LinkedListIterator? I'm absolutely out of ideas. And what kind of data can the base iterator class retrieve from the List (which is a mere interface, while the implementations of all the derived classes differ significantly) ? Sorry for so much clutter. Thanks.

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  • Is it OK to mix C and C++ in an interview?

    - by John Pell
    If I am asked in an interview to write down some code, should I completely stick with C++ or is it acceptable to "mix" the two to write easy code as it comes to my mind? I'll explain it: if I'm asked to create a "stack" data type, a C++ class is perfectly suited, while if I need to parse some strings a strtok/sscanf is far easier than STL. On the other hand, if I need a generic container STL and templates are the way to go. Everything can be done in C or in C++, but in an interview I can't code everything or remember every standard/STL function. What is an acceptable tradeoff?

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  • Problem building STLport NDK r5/ Android

    - by user558299
    Hi all, I'm trying to build STLport for Android. I got the following steps, but they are not working: 1 - Clone STLport repository using: git clone git://stlport.git.sourceforge.net/gitroot/stlport/stlport 2 - Configure environment using : ./configure --target=arm-eabi --with-extra-cxxflags="-fshort-enums" --with-extra-cflags="-fshort-enums" 3 - From src directory build it using make SYSROOT"{MY NDK path}/platforms/android-5/arch-arm/" release-static But I got the following errors: In file included from ../stlport/stl/_alloc.h:45, from ../stlport/memory:29, from dll_main.cpp:41: ../stlport/stl/_new.h:45:24: error: new: No such file or directory In file included from ../stlport/stl/_limits.h:36, from ../stlport/limits:29, from dll_main.cpp:48: ../stlport/stl/_cwchar.h:26:30: error: cstddef: No such file or directory In file included from ../stlport/stl/_utility.h:35, from ../stlport/utility:35, from dll_main.cpp:40: ../stlport/type_traits:889: error: 'declval' was not declared in this scope ../stlport/type_traits:889: error: expected primary-expression before '>' token ../stlport/type_traits:889: error: expected primary-expression before ')' token ../stlport/type_traits:889: error: 'declval' was not declared in this scope ../stlport/type_traits:889: error: expected primary-expression before '>' token ../stlport/type_traits:889: error: expected primary-expression before ')' token ../stlport/type_traits:889: error: ISO C++ forbids declaration of 'decltype' with no type ../stlport/type_traits:889: error: ISO C++ forbids in-class initialization of non-const static member 'decltype' ../stlport/type_traits:889: error: template declaration of 'int std::tr1::detail::decltype' ../stlport/type_traits:942: error: ISO C++ forbids declaration of 'decltype' with no type ../stlport/type_traits:942: error: ISO C++ forbids in-class initialization of non-const static member 'decltype' ../stlport/type_traits:942: error: template declaration of 'int std::tr1::detail::decltype' make: *** [obj/arm-eabi-gcc/so/dll_main.o] Error 1 Is there any include dir or configuration I´m missing? Thanks, Sergio

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  • Nervous about the "real" world

    - by Randy
    I am currently majoring in Computer Science and minoring in mathematics (the minor is embedded in the major). The program has a strong C++ curriculum. We have done some UNIX and assembly language (not fun) and there is C and Java on the way in future classes that I must take. The program I am in did not use the STL, but rather a STL-ish design that was created from the ground up for the program. From what I have read on, the STL and what I have taken are very similar but what I used seemed more user friendly. Some of the programs that I had to write in C++ for assignments include: a password server that utilized hashing of the passwords for security purposes, a router simulator that used a hash table and maps, a maze solver that used depth first search, a tree traveler program that traversed a tree using levelorder, postorder, inorder, selection sort, insertion sort, bit sort, radix sort, merge sort, heap sort, quick sort, topological sort, stacks, queues, priority queues, and my least favorite, red-black trees. All of this was done in three semesters which was just enough time to code them up and turn them in. That being said, if I was told to use a stack to convert an equation to infix notation or something, I would be lost for a few hours. My main concern in writing this is when I graduate and land an interview, what are some of the questions posed to assess my skills? What are some of the most important areas of computer science that are prevalent in the field? I am currently trying to get some ideas of programs I can write in C++ that interest and challenge me to keep learning the language. A sodoku solver came to mind but am lost as to where to start. I apologize for the rant, but I'm just a wee bit nervous about the future. Any tips are appreciated.

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  • C++ Iterator lifetime and detecting invalidation

    - by DK.
    Based on what's considered idiomatic in C++11: should an iterator into a custom container survive the container itself being destroyed? should it be possible to detect when an iterator becomes invalidated? are the above conditional on "debug builds" in practice? Details: I've recently been brushing up on my C++ and learning my way around C++11. As part of that, I've been writing an idiomatic wrapper around the uriparser library. Part of this is wrapping the linked list representation of parsed path components. I'm looking for advice on what's idiomatic for containers. One thing that worries me, coming most recently from garbage-collected languages, is ensuring that random objects don't just go disappearing on users if they make a mistake regarding lifetimes. To account for this, both the PathList container and its iterators keep a shared_ptr to the actual internal state object. This ensures that as long as anything pointing into that data exists, so does the data. However, looking at the STL (and lots of searching), it doesn't look like C++ containers guarantee this. I have this horrible suspicion that the expectation is to just let containers be destroyed, invalidating any iterators along with it. std::vector certainly seems to let iterators get invalidated and still (incorrectly) function. What I want to know is: what is expected from "good"/idiomatic C++11 code? Given the shiny new smart pointers, it seems kind of strange that STL allows you to easily blow your legs off by accidentally leaking an iterator. Is using shared_ptr to the backing data an unnecessary inefficiency, a good idea for debugging or something expected that STL just doesn't do? (I'm hoping that grounding this to "idiomatic C++11" avoids charges of subjectivity...)

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  • How to optimize paging for large in memory database

    - by snakefoot
    I have an application where the entire database is implemented in memory using a stl-map for each table in the database. Each item in the stl-map is a complex object with references to other items in the other stl-maps. The application works with a large amount of data, so it uses more than 500 MByte RAM. Clients are able to contact the application and get a filtered version of the entire database. This is done by running through the entire database, and finding items relevant for the client. When the application have been running for an hour or so, then Windows 2003 SP2 starts to page out parts of the RAM for the application (Eventhough there is 16 GByte RAM on the machine). After the application have been partly paged out then a client logon takes a long time (10 mins) because it now generates a page fault for each pointer lookup in the stl-map. I can see it is possible to tell Windows to lock memory in RAM, but this is generally only recommended for device drivers, and only for "small" amounts of memory. I guess a poor mans solution could be to loop through the entire memory database, and thus tell Windows we are still interested in keeping the datamodel in RAM. I guess another poor mans solution could be to disable the pagefile completely on Windows. I guess the expensive solution would be a SQL database, and then rewrite the entire application to use a database layer. Then hopefully the database system will have implemented means to for fast access. Are there other more elegant solutions ?

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  • Frustrations about which language to use [closed]

    - by Joshua
    I am way too indecisive. I have an idea for a (admittedly craptastic) GUI program, so I start writing it in C# .NET WinForms. Then like halfway through I'm like, damn I should have written this in Qt. So I start writing it in Qt and remember why I hate C++ STL iterators so much. So in my head I go LINQ C++ STL So I'm like, maybe I'll do it in WPF, I like markup to make UIs hey this is kinda like web development (read: ez pz) BUT ITS LIKE WHY GOD WHY CANT I JUST PICK ONE AND COMMIT

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  • Does Boost work with IntervalZero RTX 2009?

    - by cs-79
    Hi all Rtx experts, Have anyone implemented hard real-time app on IntervalZero Rtx environment using Boost libraries? I wish to use the Boost `unordered` data structures instead of solely relying on STL::Vector. Or Array/Vector is the only data structure supported by Rtx? * Off topic question: Can we use STL::String instead of char pointer for string in Rtx? Thanks.

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  • Android ndk-build command does nothing

    - by James
    I have a similar question to that posted here: Android NDK: why ndk-build doesn't generate .so file and a new libs folder in Eclipse? ...though I am running Windows 7, not Mac os. Essentially the ndk-build command is run, gives no error but doesn't create an .so file (also, since I'm on windows this should create a .dll and not an .so?). I tried running the command from the root, jni, src folders etc. but got the same result; cmd just returns to the prompter after a few seconds. I ran it again from the jni folder with NDK_LOG=1 parameter to see what was happening. Here is a portion of the transcript of the log results after running ndk-build in the jni folder (after it successfully identified the platform, etc.)... Android NDK: Looking for jni/Android.mk in /workspace/NdkFooActivity/jni Android NDK: Looking for jni/Android.mk in /workspace/NdkFooActivity Android NDK: Found it ! Android NDK: Found project path: /workspace/NdkFooActivity Android NDK: Ouput path: /workspace/NdkFooActivity/obj Android NDK: Parsing /cygdrive/c/android-ndk-r8/build/core/default-application.mk Android NDK: Found APP_PLATFORM=android-15 in /workspace/NdkFooActivity/project.properties Android NDK: Application local targets unknown platform 'android-15' Android NDK: Switching to android-14 Android NDK: Using build script /workspace/NdkFooActivity/jni/Android.mk Android NDK: Application 'local' is not debuggable Android NDK: Selecting release optimization mode (app is not debuggable) Android NDK: Adding import directory: /cygdrive/c/android-ndk-r8/sources Android NDK: Building application 'local' for ABI 'armeabi' Android NDK: Using target toolchain 'arm-linux-androideabi-4.4.3' for 'armeabi' ABI Android NDK: Looking for imported module with tag 'cxx-stl/system' Android NDK: Probing /cygdrive/c/android-ndk-r8/sources/cxx-stl/system/Android.mk Android NDK: Found in /cygdrive/c/android-ndk-r8/sources/cxx-stl/system Android NDK: Cygwin dependency file conversion script: ...after which point it just runs the script mentioned in the last line, then terminates. Any ideas? Thanks!

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