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  • C++ templates - matrix class

    - by lastOfMohicans
    Hi I'm learning templates in C++ so I decied to write matrix class which would be a template class. In Matrix.h file I wrote #pragma once #include "stdafx.h" #include <vector> using namespace std; template<class T> class Matrix { public: Matrix(); ~Matrix(); GetDataVector(); SetDataVector(vector<vector<T>> dataVector); bool operator == (Matrix* matrix); bool operator < (Matrix* matrix); bool operator <= (Matrix* matrix); bool operator > (Matrix* matrix); bool operator >= (Matrix* matrix); Matrix* operator + (Matrix* matrix); Matrix* operator - (Matrix* matrix); Matrix* operator * (Matrix* matrix); private: vector<vector<T>> datavector; int columns,rows; }; In Matrix cpp Visual Stuio automaticlly generated code for default constructors #include "StdAfx.h" #include "Matrix.h" Matrix::Matrix() { } Matrix::~Matrix() { } However if I want to compile this I get an error 'Matrix' : use of class template requires template argument list The error are in file Matrix.cpp in default constructors What may be the problem ??

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  • Avoiding RTTI In Java

    - by destructo_gold
    Hi, If I have a superclass, say Animal, and two subclasses: Zebra and Giraffe, If I decide to define a Vector of Animals: Vector <Animal> animals = new Vector(); and I want to say: You can add Giraffes, but you must own at least one Zebra first. What is the best way to do this without using RTTI? (instanceof)

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  • terminate called after throwing an instance of 'std::length_error'

    - by mark
    hello all, this is my first post here. As i am newbie, the problem might be stupid. I was writing a piece of code while the following error message shown, terminate called after throwing an instance of 'std::length_error' what(): basic_string::_S_create /home/gcj/finals /home/gcj/quals where Aborted the following is the offending code especially Line 39 to Line 52. It is weired for me as this block of code is almost same as the Line64 to Line79. int main(){ std::vector<std::string> dirs, need; std::string tmp_str; std::ifstream fp_in("small.in"); std::ofstream fp_out("output"); std::string::iterator iter_substr_begin, iter_substr_end; std::string slash("/"); int T, N, M; fp_in>>T; for (int t = 0; t < T; t++){ std::cout<<" time "<< t << std::endl; fp_in >> N >> M; for (int n =0; n<N; n++){ fp_in>>tmp_str; dirs.push_back(tmp_str); tmp_str.clear(); } for (int m=0; m<M; m++){ fp_in>>tmp_str; need.push_back(tmp_str); tmp_str.clear(); } for (std::vector<std::string>::iterator iter = dirs.begin(); iter!=dirs.end(); iter++){ for (std::string::iterator iter_str = (*iter).begin()+1; iter_str<(*iter).end(); ++iter_str){ if ((*iter_str)=='/') { std::string tmp_str2((*iter).begin(), iter_str); if (find(dirs.begin(), dirs.end(), tmp_str2)==dirs.end()) { dirs.push_back(tmp_str2); } } } } for (std::vector<std::string>::iterator iter_tmp = dirs.begin(); iter_tmp!= dirs.end(); ++iter_tmp) std::cout<<*iter_tmp<<" "; dirs.clear(); std::cout<<std::endl; std::cout<<" need "<<std::endl; //processing the next for (std::vector<std::string>::iterator iter_tmp = need.begin(); iter_tmp!=need.end(); ++iter_tmp) std::cout<<*iter_tmp<<" "; std::cout<<" where "; for (std::vector<std::string>::iterator iter = need.begin(); iter!=need.end(); iter++){ for (std::string::iterator iter_str = (*iter).begin()+1; iter_str<(*iter).end(); ++iter_str){ if ((*iter_str)=='/') { std::string tmp_str2((*iter).begin(), iter_str); if (find(need.begin(), need.end(), tmp_str2)==need.end()) { need.push_back(tmp_str2); } } } } for (std::vector<std::string>::iterator iter_tmp = need.begin(); iter_tmp!= need.end(); ++iter_tmp) std::cout<<*iter_tmp<<" "; need.clear(); std::cout<<std::endl; //finish processing the next } for (std::vector<std::string>::iterator iter= dirs.begin(); iter!=dirs.end(); iter++) std::cout<<*iter<<" "; std::cout<<std::endl; for (std::vector<std::string>::iterator iter= need.begin(); iter!=need.end(); iter++) std::cout<<*iter<<" "; std::cout<<std::endl; fp_out.close(); } best regards, Mark

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  • Use of for_each on map elements

    - by Antonio
    I have a map where I'd like to perform a call on every data type object member function. I yet know how to do this on any sequence but, is it possible to do it on an associative container? The closest answer I could find was this: Boost.Bind to access std::map elements in std::for_each. But I cannot use boost in my project so, is there an STL alternative that I'm missing to boost::bind? If not possible, I thought on creating a temporary sequence for pointers to the data objects and then, call for_each on it, something like this: class MyClass { public: void Method() const; } std::map<int, MyClass> Map; //... std::vector<MyClass*> Vector; std::transform(Map.begin(), Map.end(), std::back_inserter(Vector), std::mem_fun_ref(&std::map<int, MyClass>::value_type::second)); std::for_each(Vector.begin(), Vector.end(), std::mem_fun(&MyClass::Method)); It looks too obfuscated and I don't really like it. Any suggestions?

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  • ajax call to servlet puzzler

    - by vector
    Greetings! I'm having a problem getting a text value of a captcha from a servlet through ajax call. When my captcha gets created, its text value is written to session, but after refreshing the image itself though ajax call, I only get one old value of the text. Refreshing the image itself works ok, but I'm stuck getting the correct values from the session on subsequent call. On page reload I get both the new image and its new text value, no joy with ajax though. This works great for the image refresh: $("#asos").attr("src", "/ImageServlet?="+((new Date()).getTime()) ) This call to another method to get text value gives me old stuff: $.ajax({ url:"checkCaptcha", type:"GET", cache: false, success: function( data) { alert(data); } }); Any feedback will be appreciated. ps: here's the meat of the method getting the call: PrintWriter out = response.getWriter(); response.setContentType("text/html"); response.setDateHeader("Expires", 0 ); // Set standard HTTP/1.1 no-cache headers. response.setHeader("Cache-Control", "no-store, no-cache, must-revalidate"); // Set IE extended HTTP/1.1 no-cache headers (use addHeader). response.addHeader("Cache-Control", "post-check=0, pre-check=0"); // Set standard HTTP/1.0 no-cache header. response.setHeader("Pragma", "no-cache"); out.print( request.getSession( ).getAttribute("randomPixValue") ); out.close();

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  • 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.

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  • What C++ pitfalls should I avoid ?

    - by Craig H
    I remember first learning about vectors in the STL and after some time, I wanted to use a vector of bools for one of my projects. After seeing some strange behavior and doing some research, I learned that a vector of bools is not really a vector of bools. Anyone out there have any other common pitfalls to avoid in C++?

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  • About variadic templates

    - by chedi
    Hi, I'm currently experiencing with the new c++0x variadic templates, and it's quit fun, Although I have a question about the process of member instanciation. in this example, I'm trying to emulate the strongly typed enum with the possibility of choose a random valid strong enum (this is used for unit testing). #include<vector> #include<iostream> using namespace std; template<unsigned... values> struct sp_enum; /* this is the solution I found, declaring a globar var vector<unsigned> _data; and it work just fine */ template<> struct sp_enum<>{ static const unsigned _count = 0; static vector<unsigned> _data; }; vector<unsigned> sp_enum<>::_data; template<unsigned T, unsigned... values> struct sp_enum<T, values...> : private sp_enum<values...>{ static const unsigned _count = sp_enum<values...>::_count+1; static vector<unsigned> _data; sp_enum( ) : sp_enum<values...>(values...) {_data.push_back(T);} sp_enum(unsigned v ) {_data.push_back(v);} sp_enum(unsigned v, unsigned...) : sp_enum<values...>(values...) {_data.push_back(v);} }; template<unsigned T, unsigned... values> vector<unsigned> sp_enum<T, values...>::_data; int main(){ enum class t:unsigned{Default = 5, t1, t2}; sp_enum<t::Default, t::t1, t::t2> test; cout <<test._count << endl << test._data.size() << endl; for(auto i= test._data.rbegin();i != test._data.rend();++i){cout<< *i<< ":";} } the result I'm getting with this code is : 3 1 5: can someone point me what I'm messing here ??? Ps: using gcc 4.4.3

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  • cakePHP - ACL tutorial & SQL Error: 1104

    - by vector
    Greetings! I run into a problem/bug in production environment with SQL Error: 1104 when deploying a project secured with the ACL tutorial. The full error: SQL Error: 1104: The SELECT would examine more than MAX_JOIN_SIZE rows; check your WHERE and use SET SQL_BIG_SELECTS=1 or SET SQL_MAX_JOIN_SIZE=# if the SELECT is okay [CORE/cake/libs/model/datasources/dbo_source.php, line 666] I've build a small site, worked through the ACL tutorial from the official cake book and locally everything is spiffy. dev. setup consists of: XAMPP: myslq 5.1.33, php 5.3 cakePHP 1.2.7 prod. setup: mysql 5.0.33 php 5.2.2 One of the differences I noticed with mysql setup between local and production servers, is that SQL_BIG_SELECTS is disabled on the production server ( and I don't have privileges to change that, posted a support ticked, didn't hear anything yet) Is there anything I can do about this from my end? Thanks in advance.

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  • Basic doubt about sensor usage

    - by Al
    Suppose I have a cellphone with accelerometer and magnetometer, and want to determine its absolute (wrt North/East/South/West) 3d position. Imagine the phone is laid vertically, with the screen facing me, the "up" vector pointing to the ceil. Whenever I tilt, the accelerometer allows me to get the "up" vector info change. The problem is that if I tilt the device and put it horizontally (screen now facing ceil, and "up" vector pointing to the opposite of where I am), then the up vector doesn't get updated any more if I rotate the phone horizontally on the table. This is something that clearly is detected by the magnetometer now. So, the question is, when to know where to use acc or mag for each case? Is there a generic way to achieve this?

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  • Memory leak dyld dlopen

    - by imthi
    I am getting leak and I cannot detect from where this is happening. The stack trace does not give full info after dyld open. For few leaks I am not getting any stack trace info. All I get is only object memory address. Is anyone else facing the same issue. I am using XCode 3.2 on show leopard. 18 0x103038 17 0x1033c7 16 0x1034a1 15 0x90145f48 14 dyld dlopen 13 dyld dyld::link(ImageLoader*, bool, ImageLoader::RPathChain const&) 12 dyld ImageLoader::link(ImageLoader::LinkContext const&, bool, bool, ImageLoader::RPathChain const&) 11 dyld ImageLoader::recursiveLoadLibraries(ImageLoader::LinkContext const&, bool, ImageLoader::RPathChain const&) 10 dyld dyld::libraryLocator(char const*, bool, char const*, ImageLoader::RPathChain const*) 9 dyld dyld::load(char const*, dyld::LoadContext const&) 8 dyld dyld::loadPhase0(char const*, dyld::LoadContext const&, std::vector<char const*, std::allocator<char const*> >*) 7 dyld dyld::loadPhase1(char const*, dyld::LoadContext const&, std::vector<char const*, std::allocator<char const*> >*) 6 dyld dyld::loadPhase3(char const*, dyld::LoadContext const&, std::vector<char const*, std::allocator<char const*> >*) 5 dyld dyld::loadPhase4(char const*, dyld::LoadContext const&, std::vector<char const*, std::allocator<char const*> >*) 4 dyld dyld::loadPhase5(char const*, dyld::LoadContext const&, std::vector<char const*, std::allocator<char const*> >*) 3 dyld dyld::mkstringf(char const*, ...) 2 dyld strdup 1 dyld mallocenter

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  • Architecture for Qt SIGNAL with subclass-specific, templated argument type

    - by Barry Wark
    I am developing a scientific data acquisition application using Qt. Since I'm not a deep expert in Qt, I'd like some architecture advise from the community on the following problem: The application supports several hardware acquisition interfaces but I would like to provide an common API on top of those interfaces. Each interface has a sample data type and a units for its data. So I'm representing a vector of samples from each device as a std::vector of Boost.Units quantities (i.e. std::vector<boost::units::quantity<unit,sample_type> >). I'd like to use a multi-cast style architecture, where each data source broadcasts newly received data to 1 or more interested parties. Qt's Signal/Slot mechanism is an obvious fit for this style. So, I'd like each data source to emit a signal like typedef std::vector<boost::units::quantity<unit,sample_type> > SampleVector signals: void samplesAcquired(SampleVector sampleVector); for the unit and sample_type appropriate for that device. Since tempalted QObject subclasses aren't supported by the meta-object compiler, there doesn't seem to be a way to have a (tempalted) base class for all data sources which defines the samplesAcquired Signal. In other words, the following won't work: template<T,U> //sample type and units class DataSource : public QObject { Q_OBJECT ... public: typedef std::vector<boost::units::quantity<U,T> > SampleVector signals: void samplesAcquired(SampleVector sampleVector); }; The best option I've been able to come up with is a two-layered approach: template<T,U> //sample type and units class IAcquiredSamples { public: typedef std::vector<boost::units::quantity<U,T> > SampleVector virtual shared_ptr<SampleVector> acquiredData(TimeStamp ts, unsigned long nsamples); }; class DataSource : public QObject { ... signals: void samplesAcquired(TimeStamp ts, unsigned long nsamples); }; The samplesAcquired signal now gives a timestamp and number of samples for the acquisition and clients must use the IAcquiredSamples API to retrieve those samples. Obviously data sources must subclass both DataSource and IAcquiredSamples. The disadvantage of this approach appears to be a loss of simplicity in the API... it would be much nicer if clients could get the acquired samples in the Slot connected. Being able to use Qt's queued connections would also make threading issues easier instead of having to manage them in the acquiredData method within each subclass. One other possibility, is to use a QVariant argument. This necessarily puts the onus on subclass to register their particular sample vector type with Q_REGISTER_METATYPE/qRegisterMetaType. Not really a big deal. Clients of the base class however, will have no way of knowing what type the QVariant value type is, unless a tag struct is also passed with the signal. I consider this solution at least as convoluted as the one above, as it forces clients of the abstract base class API to deal with some of the gnarlier aspects of type system. So, is there a way to achieve the templated signal parameter? Is there a better architecture than the one I've proposed?

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  • How to pass parameters to manage_shared_memory.construct() in Boost.Interprocess

    - by recipriversexclusion
    I've stared at the Boost.Interprocess documentation for hours but still haven't been able to figure this out. In the doc, they have an example of creating a vector in shared memory like so: //Define an STL compatible allocator of ints that allocates from the managed_shared_memory. //This allocator will allow placing containers in the segment typedef allocator<int, managed_shared_memory::segment_manager> ShmemAllocator; //Alias a vector that uses the previous STL-like allocator so that allocates //its values from the segment typedef vector<int, ShmemAllocator> MyVector; int main(int argc, char *argv[]) { //Create a new segment with given name and size managed_shared_memory segment(create_only, "MySharedMemory", 65536); //Initialize shared memory STL-compatible allocator const ShmemAllocator alloc_inst (segment.get_segment_manager()); //Construct a vector named "MyVector" in shared memory with argument alloc_inst MyVector *myvector = segment.construct<MyVector>("MyVector")(alloc_inst); Now, I understand this. What I'm stuck is how to pass a second parameter to segment.construct() to specify the number of elements. The interprocess document gives the prototype for construct() as MyType *ptr = managed_memory_segment.construct<MyType>("Name") (par1, par2...); but when I try MyVector *myvector = segment.construct<MyVector>("MyVector")(100, alloc_inst); I get compilation errors. My questions are: Who actually gets passed the parameters par1, par2 from segment.construct, the constructor of the object, e.g. vector? My understanding is that the template allocator parameter is being passed. Is that correct? How can I add another parameter, in addition to alloc_inst that is required by the constructor of the object being created in shared memory? There's very little information other than the terse Boost docs on this.

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  • How to create a function with vectors and vertical asymptote using MATLAB

    - by Pedro J Trinidad
    Plot the function f(x) = 1.5x / x-4 for -10 equal or less than X equal or less than 10. Notice that the function have a vertical asymptote at x = 4. Plot the function by creating two vectors for the domain of x. The first vector (call it x1) with elements from -10 to 3.7, and the second vector (calle it x2) with elements from 4.3 to 10. For each of the X vector create a Y vector (call them y1 and y2) with the corresponding values of Y according to the function. To plot the function make two curves in the same plot (y1 vs. x1 and y2 vs. x2).

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  • Iterating backward

    - by MBennett
    Suppose I have a vector<int> myvec and I want to loop through all of the elements in reverse. I can think of a few ways of doing this: for (vector<int>::iterator it = myvec.end() - 1; it >= myvec.begin(); --it) { // do stuff here } for (vector<int>::reverse_iterator rit = myvec.rbegin(); rit != myvec.rend(); ++rit) { // do stuff here } for (int i = myvec.size() - 1; i >= 0; --i) { // do stuff here } So my question is when should I use each? Is there a difference? I know that the first one is dangerous because if I pass in an empty vector, then myvec.end() - 1 is undefined, but are there any other hazards or inefficiencies with this?

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  • Detecting Acceleration in a car (iPhone Accelerometer)

    - by TheGazzardian
    Hello, I am working on an iPhone app where we are trying to calculate the acceleration of a moving car. Similar apps have accomplished this (Dynolicious), but the difference is that this app is designed to be used during general city driving, not on a drag strip. This leads us to one big concern that Dynolicious was luckily able to avoid: hills. Yes, hills. There are two important stages to this: calibration, and actual driving. Our initial run was simple and suffered the consequences. During the calibration stage, I took the average force on the phone, and during running, I just subtracted the average force from the current force to get the current acceleration this frame. The problem with this is that the typical car receives much more force than just the forward force - everything from turning to potholes was causing the values to go out of sync with what was really happening. The next run was to add the condition that the iPhone must be oriented in such a way that the screen was facing toward the back of the car. Using this method, I attempted to follow only force on the z-axis, but this obviously lead to problems unless the iPhone was oriented directly upright, because of gravity. Some trigonometry later, and I had managed to work gravity out of the equation, so that the car was actually being read very, very well by the iPhone. Until I hit a slope. As soon as the angle of the car changed, suddenly I was receiving accelerations and decelerations that didn't make sense, and we were once again going out of sync. Talking with someone a lot smarter than me at math lead to a solution that I have been trying to implement for longer than I would like to admit. It's steps are as follows: 1) During calibration, measure gravity as a vector instead of a size. Store that vector. 2) When the car initially moves forward, take the vector of motion and subtract gravity. Use this as the forward momentum. (Ignore, for now, the user cases where this will be difficult and let's concentrate on the math :) 3) From the forward vector and the gravity vector, construct a plane. 4) Whenever a force is received, project it onto said plane to get rid of sideways force/etc. 5) Then, use that force, the known magnitude of gravity, and the known direction of forward motion to essentially solve a triangle to get the forward vector. The problem that is causing the most difficulty in this new system is not step 5, which I have gotten to the point where all the numbers look as they should. The difficult part is actually the detection of the forward vector. I am selecting vectors whose magnitude exceeds gravity, and from there, averaging them and subtracting gravity. (I am doing some error checking to make sure that I am not using a force just because the iPhone accelerometer was off by a bit, which happens more frequently than I would like). But if I plot these vectors that I am using, they actually vary by an angle of about 20-30 degrees, which can lead to some strong inaccuracies. The end result is that the app is even more inaccurate now than before. So basically - all you math and iPhone brains out there - any glaring errors? Any potentially better solutions? Any experience that could be useful at all? Award: offering a bounty of $250 to the first answer that leads to a solution.

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  • Good way to maintain Muliple level selection menu list in J2ME

    - by geoaxis
    Hello, I need a good way to maintain multiple form level data for menue selection. So for example If I have A and B, each might Have 1 2 3 so A A1 A2 A3 B B1 B2 B3 And this can continue for long, so that I could have A - A1 - A1.1 - A1.1.1 -.... I have the following class in place, works ok But I suspect we could have better. I just need to perform selection ni a selection tree like Widget, but each level of selection comes in another form (in J2ME) import java.util.Vector; public class Tag { private String tag; private Vector childTags; private Tag parent; Tag(String tag, Vector childtag) { this.tag = tag; this.childTags= childTags; } public void setChildTags(Vector childTags) { this.childTags = childTags; } public Vector getChildTags() { return this.childTags; } public String getTag() { return this.tag; } public String toString(int depth) { String a =""; if(depth==0) { a = a + this.getTag(); } if(this.getChildTags()!= null) { for(int k=0;k <this.getChildTags().capacity(); k++) { for (int i=0; i<depth; i++ ) { a = a + ("-"); } a = a+ ( ((Tag)this.getChildTags().elementAt(k)).toString(depth++)); } } return a; } }

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  • Seeking STL-aware c++filt

    - by Don Wakefield
    In my development environment, I'm compiling a code base using GNU C++ 3.4.6. Code is under development, and unfortunately crashes now and then. It's nice to be able to run the traceback through a demangler, and I use c++filt 3.4. The problem comes when functions have a number of STL parameters. Consider My_callback::operator()( Status&, std::set<std::string> const&, std::vector<My_parameter*> const&, My_attribute_set const&, std::vector<My_parameter_base*> const&, std::vector<My_parameter> const&, std::set<std::string> const& ) { // ... } When this function is in the traceback, the mangled output on my platform is: (_ZN30My_callbackclER11StatusRKSt3setISsSt4lessISsESaISsEERKSt6vectorIP13My_parameterSaISB_EERK17My_attribute_setRKS9_IP18My_parameter_baseSaISK_EERKS9_ISA_SaISA_EES8_+0x76a) [0x13ffdaa] c++filt kindly demangles it to (My_callback::operator()(Status&, std::set<std::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::less<std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, std::allocator<std::basic_string<char, std::char_traits<char>, std::allocator<char> > > > const&, std::vector<My_parameter*, std::allocator<My_parameter*> > const&, My_attribute_set const&, std::vector<My_parameter_base*, std::allocator<My_parameter_base*> > const&, std::vector<My_parameter, std::allocator<My_parameter> > const&, std::set<std::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::less<std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, std::allocator<std::basic_string<char, std::char_traits<char>, std::allocator<char> > > > const&)+0x76a) [0x13ffdaa] This is the same problem as compiler errors encountered when using templates. However, the STL is a fairly regular and recognizable package of templates. So what I'm hoping is that someone out there has created an enhanced version of c++filt which would dump something closer to the original function signature. Any hints?

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  • Convert Decimal to ASCII

    - by Dan Snyder
    I'm having difficulty using reinterpret_cast. Before I show you my code I'll let you know what I'm trying to do. I'm trying to get a filename from a vector full of data being used by a MIPS I processor I designed. Basically what I do is compile a binary from a test program for my processor, dump all the hex's from the binary into a vector in my c++ program, convert all of those hex's to decimal integers and store them in a DataMemory vector which is the data memory unit for my processor. I also have instruction memory. So When my processor runs a SYSCALL instruction such as "Open File" my C++ operating system emulator receives a pointer to the beginning of the filename in my data memory. So keep in mind that data memory is full of ints, strings, globals, locals, all sorts of stuff. When I'm told where the filename starts I do the following: Convert the whole decimal integer element that is being pointed to to its ASCII character representation, and then search from left to right to see if the string terminates, if not then just load each character consecutively into a "filename" string. Do this until termination of the string in memory and then store filename in a table. My difficulty is generating filename from my memory. Here is an example of what I'm trying to do: C++ Syntax (Toggle Plain Text) 1.Index Vector NewVector ASCII filename 2.0 240faef0 128123792 'abc7' 'a' 3.0 240faef0 128123792 'abc7' 'ab' 4.0 240faef0 128123792 'abc7' 'abc' 5.0 240faef0 128123792 'abc7' 'abc7' 6.1 1234567a 243225 'k2s0' 'abc7k' 7.1 1234567a 243225 'k2s0' 'abc7k2' 8.1 1234567a 243225 'k2s0' 'abc7k2s' 9. //EXIT LOOP// 10.1 1234567a 243225 'k2s0' 'abc7k2s' Index Vector NewVector ASCII filename 0 240faef0 128123792 'abc7' 'a' 0 240faef0 128123792 'abc7' 'ab' 0 240faef0 128123792 'abc7' 'abc' 0 240faef0 128123792 'abc7' 'abc7' 1 1234567a 243225 'k2s0' 'abc7k' 1 1234567a 243225 'k2s0' 'abc7k2' 1 1234567a 243225 'k2s0' 'abc7k2s' //EXIT LOOP// 1 1234567a 243225 'k2s0' 'abc7k2s' Here is the code that I've written so far to get filename (I'm just applying this to element 1000 of my DataMemory vector to test functionality. 1000 is arbitrary.): C++ Syntax (Toggle Plain Text) 1.int i = 0; 2.int step = 1000;//top->a0; 3.string filename; 4.char *temp = reinterpret_cast<char*>( DataMemory[1000] );//convert to char 5.cout << "a0:" << top->a0 << endl;//pointer supplied 6.cout << "Data:" << DataMemory[top->a0] << endl;//my vector at pointed to location 7.cout << "Data(1000):" << DataMemory[1000] << endl;//the element I'm testing 8.cout << "Characters:" << &temp << endl;//my temporary char array 9. 10.while(&temp[i]!=0) 11.{ 12. filename+=temp[i];//add most recent non-terminated character to string 13. i++; 14. if(i==4)//when 4 chatacters have been added.. 15. { 16. i=0; 17. step+=1;//restart loop at the next element in DataMemory 18. temp = reinterpret_cast<char*>( DataMemory[step] ); 19. } 20. } 21. cout << "Filename:" << filename << endl; int i = 0; int step = 1000;//top-a0; string filename; char *temp = reinterpret_cast( DataMemory[1000] );//convert to char cout << "a0:" << top-a0 << endl;//pointer supplied cout << "Data:" << DataMemory[top-a0] << endl;//my vector at pointed to location cout << "Data(1000):" << DataMemory[1000] << endl;//the element I'm testing cout << "Characters:" << &temp << endl;//my temporary char array while(&temp[i]!=0) { filename+=temp[i];//add most recent non-terminated character to string i++; if(i==3)//when 4 chatacters have been added.. { i=0; step+=1;//restart loop at the next element in DataMemory temp = reinterpret_cast( DataMemory[step] ); } } cout << "Filename:" << filename << endl; So the issue is that when I do the conversion of my decimal element to a char array I assume that 8 hex #'s will give me 4 characters. Why isn't this this case? Here is my output: C++ Syntax (Toggle Plain Text) 1.a0:0 2.Data:0 3.Data(1000):4428576 4.Characters:0x7fff5fbff128 5.Segmentation fault

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  • using extends with Java Generics

    - by Sandro
    Lets say that I have the following code: public class Shelter<A extends Animal, B extends Animal> { List<A> topFloor = new Vector<A>(); List<B> bottomFloor = new Vector<B>(); public A getFirstTopFloorAnimal(){return topFloor.firstElement();} public B getFirstBottomFloorAnimal(){return bottomFloor.firstElement();} //This compiles but when I try to use it, it only returns objects public List<Animal> getAnimals() { Vector a = new Vector(topFloor); a.addAll(bottomFloor); return a; } } Now for somereason the following code compiles. But when I try to use getAnimals() I get a of objects instead of Animal. Any ideas why this is? Does this have to do with the List is NOT a List idea in the Generics tutorial? Thank you.

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  • The fastest way to iterate through a collection of objects

    - by Trev
    Hello all, First to give you some background: I have some research code which performs a Monte Carlo simulation, essential what happens is I iterate through a collection of objects, compute a number of vectors from their surface then for each vector I iterate through the collection of objects again to see if the vector hits another object (similar to ray tracing). The pseudo code would look something like this for each object { for a number of vectors { do some computations for each object { check if vector intersects } } } As the number of objects can be quite large and the amount of rays is even larger I thought it would be wise to optimise how I iterate through the collection of objects. I created some test code which tests arrays, lists and vectors and for my first test cases found that vectors iterators were around twice as fast as arrays however when I implemented a vector in my code in was somewhat slower than the array I was using before. So I went back to the test code and increased the complexity of the object function each loop was calling (a dummy function equivalent to 'check if vector intersects') and I found that when the complexity of the function increases the execution time gap between arrays and vectors reduces until eventually the array was quicker. Does anyone know why this occurs? It seems strange that execution time inside the loop should effect the outer loop run time.

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  • Calling unmanaged c++ code in C# Mixed with STL

    - by Turtle
    Hey, I want to call unmanaged c++ code in C# The function interface is like following(I simplified it to make it easy to understand) Face genMesh(int param1, int param2); Face is a struct defined as: struct Face{ vector<float> nodes; vector<int> indexs; } I googled and read the MSDN docs found ways to call simple c/c++ unmanged code in C#, also know how to hand the struct as return value. And My question is how to handle "vector". I did not find rules about mapping between vector and some types in C# Thanks!

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  • Output is different for R-value and L-value. Why?

    - by Leonid Volnitsky
    Can someone explain to me why output for R-value is different from L-value? #include <iostream> #include <vector> using namespace std; template<typename Ct> struct ct_wrapper { Ct&& ct; // R or L ref explicit ct_wrapper(Ct&& ct) : ct(std::forward<Ct>(ct)) { std::cout << this->ct[1];}; }; int main() { // L-val vector<int> v{1,2,3}; ct_wrapper<vector<int>&> lv(v); cout << endl << lv.ct[0] << lv.ct[1] << lv.ct[2] << endl; // R-val ct_wrapper<vector<int>&&> rv(vector<int>{1,2,3}); cout << endl << rv.ct[0] << rv.ct[1] << rv.ct[2] << endl; } Output (same for gcc48 and clang32): 2 123 2 003

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  • map operator [] operands

    - by Jamie Cook
    Hi all I have the following in a member function int tt = 6; vector<set<int>>& temp = m_egressCandidatesByDestAndOtMode[tt]; set<int>& egressCandidateStops = temp.at(dest); and the following declaration of a member variable map<int, vector<set<int>>> m_egressCandidatesByDestAndOtMode; However I get an error when compiling (Intel Compiler 11.0) 1>C:\projects\svn\bdk\Source\ZenithAssignment\src\Iteration\PtBranchAndBoundIterationOriginRunner.cpp(85): error: no operator "[]" matches these operands 1> operand types are: const std::map<int, std::vector<std::set<int, std::less<int>, std::allocator<int>>, std::allocator<std::set<int, std::less<int>, std::allocator<int>>>>, std::less<int>, std::allocator<std::pair<const int, std::vector<std::set<int, std::less<int>, std::allocator<int>>, std::allocator<std::set<int, std::less<int>, std::allocator<int>>>>>>> [ const int ] 1> vector<set<int>>& temp = m_egressCandidatesByDestAndOtMode[tt]; 1> ^ I know it's got to be something silly but I can't see what I've done wrong.

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  • Are returned locals automatically xvalues

    - by mark
    Following on from a comment I made on this: passing std::vector to constructor and move semantics Is the std::move necessary in the following code, to ensure that the returned value is a xvalue? std::vector<string> buildVector() { std::vector<string> local; // .... build a vector return std::move(local); } It is my understanding that this is required. I have often seen this used when returning a std::unique_ptr from a function, however GManNickG made the following comment: It is my understanding that in a return statement all local variables are automatically xvalues (expiring values) and will be moved, but I'm unsure if that only applies to the returned object itself. So OP should go ahead and put that in there until I'm more confident it shouldn't have to be. :) Can anyone clarify if the std::move is necessary? Is the behaviour compiler dependent?

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