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  • vector<string> or vector<char *>?

    - by Aaron
    Question: What is the difference between: vector<string> and vector<char *>? How would I pass a value of data type: string to a function, that specifically accepts: const char *? For instance: vector<string> args(argv, argv + argc); vector<string>::iterator i; void foo (const char *); //*i I understand using vector<char *>: I'll have to copy the data, as well as the pointer Edit: Thanks for input!

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  • Vector of vectors of T in template<T> class

    - by topright
    Why this code does not compile (Cygwin)? #include <vector> template <class Ttile> class Tilemap { typedef std::vector< Ttile > TtileRow; typedef std::vector< TtileRow > TtileMap; typedef TtileMap::iterator TtileMapIterator; // error here }; error: type std::vector<std::vector<Ttile, std::allocator<_CharT> >, std::allocator<std::vector<Ttile, std::allocator<_CharT> > > >' is not derived from typeTilemap'

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  • Trimming a vector of strings

    - by dreamlax
    I have an std::vector of std::strings containing data similar to this: [0] = "" [1] = "Abc" [2] = "Def" [3] = "" [4] = "Ghi" [5] = "" [6] = "" How can I get a vector containing the 4 strings from 1 to 4? (i.e. I want to trim all blank strings from the start and end of the vector): [0] = "Abc" [1] = "Def" [2] = "" [3] = "Ghi" Currently, I am using a forward iterator to make my way up to "Abc" and a reverse iterator to make my way back to "Ghi", and then constructing a new vector using those iterators. This method works, but I want to know if there is an easier way to trim these elements. P.S. I'm a C++ noob. Edit Also, I should mention that the vector may be composed entirely of blank strings, in which case a 0-sized vector would be the desired result.

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  • Boolean algebra simplification

    - by xbonez
    I need to reduce this boolean expression to its simplest form. Its given that the simplest form contains 3 terms and 7 literals. The expression is: x'yz + w'x'z + x'y + wxy + w'y'z We tried this in class, and even out recitation teacher could not figure it out. Any help would be appreciated.

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  • Unexpected result in C algebra for search algorithm.

    - by Rhys
    Hi, I've implemented this search algorithm for an ordered array of integers. It works fine for the first data set I feed it (500 integers), but fails on longer searches. However, all of the sets work perfectly with the other four search algorithms I've implemented for the assignment. This is the function that returns a seg fault on line 178 (due to an unexpected negative m value). Any help would be greatly appreciated. CODE: 155 /* perform Algortihm 'InterPolationSearch' on the set 156 * and if 'key' is found in the set return it's index 157 * otherwise return -1 */ 158 int 159 interpolation_search(int *set, int len, int key) 160 { 161 int l = 0; 162 int r = len - 1; 163 int m; 164 165 while (set[l] < key && set[r] >= key) 166 { 167 168 printf ("m = l + ((key - set[l]) * (r - l)) / (set[r] - set[l])\n"); 169 170 printf ("m = %d + ((%d - %d) * (%d - %d)) / (%d - %d);\n", l, key, set[l], r, l, set[r], set[l]); 171 m = l + ((key - set[l]) * (r - l)) / (set[r] - set[l]); 172 printf ("m = %d\n", m); 173 174 #ifdef COUNT_COMPARES 175 g_compares++; 176 #endif 177 178 if (set[m] < key) 179 l = m + 1; 180 else if (set[m] > key) 181 r = m - 1; 182 else 183 return m; 184 } 185 186 if (set[l] == key) 187 return l; 188 else 189 return -1; 190 } OUTPUT: m = l + ((key - set[l]) * (r - l)) / (set[r] - set[l]) m = 0 + ((68816 - 0) * (100000 - 0)) / (114836 - 0); m = -14876 Thankyou! Rhys

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  • C++ std::vector insert segfault

    - by ArunSaha
    I am writing a test program to understand vector's better. In one of the scenarios, I am trying to insert a value into the vector at a specified position. The code compiles clean. However, on execution, it is throwing a Segmentation Fault from the v8.insert(..) line (see code below). I am confused. Can somebody point me to what is wrong in my code? #define UNIT_TEST(x) assert(x) #define ENSURE(x) assert(x) #include <vector> typedef std::vector< int > intVector; typedef std::vector< int >::iterator intVectorIterator; typedef std::vector< int >::const_iterator intVectorConstIterator; intVectorIterator find( intVector v, int key ); void test_insert(); intVectorIterator find( intVector v, int key ) { for( intVectorIterator it = v.begin(); it != v.end(); ++it ) { if( *it == key ) { return it; } } return v.end(); } void test_insert() { const int values[] = {10, 20, 30, 40, 50}; const size_t valuesLength = sizeof( values ) / sizeof( values[ 0 ] ); size_t index = 0; const int insertValue = 5; intVector v8; for( index = 0; index < valuesLength; ++index ) { v8.push_back( values[ index ] ); } ENSURE( v8.size() == valuesLength ); for( index = 0; index < valuesLength; ++index ) { printf( "index = %u\n", index ); intVectorIterator it = find( v8, values[ index ] ); ENSURE( it != v8.end() ); ENSURE( *it == values[ index ] ); // intVectorIterator itToInsertedItem = v8.insert( it, insertValue ); // line 51 // UNIT_TEST( *itToInsertedItem == insertValue ); } } int main() { test_insert(); return 0; } $ ./a.out index = 0 Segmentation Fault (core dumped) (gdb) bt #0 0xff3a03ec in memmove () from /platform/SUNW,T5140/lib/libc_psr.so.1 #1 0x00012064 in std::__copy_move_backward<false, true, std::random_access_iterator_tag>::__copy_move_b<int> (__first=0x23e48, __last=0x23450, __result=0x23454) at /local/gcc/4.4.1/lib/gcc/sparc-sun-solaris2.10/4.4.1/../../../../include/c++/4.4.1/bits/stl_algobase.h:575 #2 0x00011f08 in std::__copy_move_backward_a<false, int*, int*> (__first=0x23e48, __last=0x23450, __result=0x23454) at /local/gcc/4.4.1/lib/gcc/sparc-sun-solaris2.10/4.4.1/../../../../include/c++/4.4.1/bits/stl_algobase.h:595 #3 0x00011d00 in std::__copy_move_backward_a2<false, int*, int*> (__first=0x23e48, __last=0x23450, __result=0x23454) at /local/gcc/4.4.1/lib/gcc/sparc-sun-solaris2.10/4.4.1/../../../../include/c++/4.4.1/bits/stl_algobase.h:605 #4 0x000119b8 in std::copy_backward<int*, int*> (__first=0x23e48, __last=0x23450, __result=0x23454) at /local/gcc/4.4.1/lib/gcc/sparc-sun-solaris2.10/4.4.1/../../../../include/c++/4.4.1/bits/stl_algobase.h:640 #5 0x000113ac in std::vector<int, std::allocator<int> >::_M_insert_aux (this=0xffbfeba0, __position=..., __x=@0xffbfebac) at /local/gcc/4.4.1/lib/gcc/sparc-sun-solaris2.10/4.4.1/../../../../include/c++/4.4.1/bits/vector.tcc:308 #6 0x00011120 in std::vector<int, std::allocator<int> >::insert (this=0xffbfeba0, __position=..., __x=@0xffbfebac) at /local/gcc/4.4.1/lib/gcc/sparc-sun-solaris2.10/4.4.1/../../../../include/c++/4.4.1/bits/vector.tcc:126 #7 0x00010bc0 in test_insert () at vector_insert_test.cpp:51 #8 0x00010c48 in main () at vector_insert_test.cpp:58 (gdb) q

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  • crash when using stl vector at instead of operator[]

    - by Jamie Cook
    I have a method as follows (from a class than implements TBB task interface - not currently multithreading though) My problem is that two ways of accessing a vector are causing quite different behaviour - one works and the other causes the entire program to bomb out quite spectacularly (this is a plugin and normally a crash will be caught by the host - but this one takes out the host program as well! As I said quite spectacular) void PtBranchAndBoundIterationOriginRunner::runOrigin(int origin, int time) const // NOTE: const method { BOOST_FOREACH(int accessMode, m_props->GetAccessModes()) { // get a const reference to appropriate vector from member variable // map<int, vector<double>> m_rowTotalsByAccessMode; const vector<double>& rowTotalsForAccessMode = m_rowTotalsByAccessMode.find(accessMode)->second; if (origin != 129) continue; // Additional debug constrain: I know that the vector only has one non-zero element at index 129 m_job->Write("size: " + ToString(rowTotalsForAccessMode.size())); try { // check for early return... i.e. nothing to do for this origin if (!rowTotalsForAccessMode[origin]) continue; // <- this works if (!rowTotalsForAccessMode.at(origin)) continue; // <- this crashes } catch (...) { m_job->Write("Caught an exception"); // but its not an exception } // do some other stuff } } I hate not putting in well defined questions but at the moment my best phrasing is : "WTF?" I'm compiling this with Intel C++ 11.0.074 [IA-32] using Microsoft (R) Visual Studio Version 9.0.21022.8 and my implementation of vector has const_reference operator[](size_type _Pos) const { // subscript nonmutable sequence #if _HAS_ITERATOR_DEBUGGING if (size() <= _Pos) { _DEBUG_ERROR("vector subscript out of range"); _SCL_SECURE_OUT_OF_RANGE; } #endif /* _HAS_ITERATOR_DEBUGGING */ _SCL_SECURE_VALIDATE_RANGE(_Pos < size()); return (*(_Myfirst + _Pos)); } (Iterator debugging is off - I'm pretty sure) and const_reference at(size_type _Pos) const { // subscript nonmutable sequence with checking if (size() <= _Pos) _Xran(); return (*(begin() + _Pos)); } So the only difference I can see is that at calls begin instead of simply using _Myfirst - but how could that possibly be causing such a huge difference in behaviour?

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  • how to cout a vector of structs (that's a class member, using extraction operator)

    - by Julz
    hi, i'm trying to simply cout the elements of a vector using an overloaded extraction operator. the vector contians Point, which is just a struct containing two doubles. the vector is a private member of a class called Polygon, so heres my Point.h #ifndef POINT_H #define POINT_H #include <iostream> #include <string> #include <sstream> struct Point { double x; double y; //constructor Point() { x = 0.0; y = 0.0; } friend std::istream& operator >>(std::istream& stream, Point &p) { stream >> std::ws; stream >> p.x; stream >> p.y; return stream; } friend std::ostream& operator << (std::ostream& stream, Point &p) { stream << p.x << p.y; return stream; } }; #endif my Polygon.h #ifndef POLYGON_H #define POLYGON_H #include "Segment.h" #include <vector> class Polygon { //insertion operator needs work friend std::istream & operator >> (std::istream &inStream, Polygon &vertStr); // extraction operator friend std::ostream & operator << (std::ostream &outStream, const Polygon &vertStr); public: //Constructor Polygon(const std::vector<Point> &theVerts); //Default Constructor Polygon(); //Copy Constructor Polygon(const Polygon &polyCopy); //Accessor/Modifier methods inline std::vector<Point> getVector() const {return vertices;} //Return number of Vector elements inline int sizeOfVect() const {return vertices.size();} //add Point elements to vector inline void setVertices(const Point &theVerts){vertices.push_back (theVerts);} private: std::vector<Point> vertices; }; and Polygon.cc using namespace std; #include "Polygon.h" // Constructor Polygon::Polygon(const vector<Point> &theVerts) { vertices = theVerts; } //Default Constructor Polygon::Polygon(){} istream & operator >> (istream &inStream, Polygon::Polygon &vertStr) { inStream >> ws; inStream >> vertStr; return inStream; } // extraction operator ostream & operator << (ostream &outStream, const Polygon::Polygon &vertStr) { outStream << vertStr.vertices << endl; return outStream; } i figure my Point insertion/extraction is right, i can insert and cout using it and i figure i should be able to just...... cout << myPoly[i] << endl; in my driver? (in a loop) or even... cout << myPoly[0] << endl; without a loop? i've tried all sorts of myPoly.at[i]; myPoly.vertices[i]; etc etc also tried all veriations in my extraction function outStream << vertStr.vertices[i] << endl; within loops, etc etc. when i just create a... vector<Point> myVect; in my driver i can just... cout << myVect.at(i) << endl; no problems. tried to find an answer for days, really lost and not through lack of trying!!! thanks in advance for any help. please excuse my lack of comments and formatting also there's bits and pieces missing but i really just need an answer to this problem thanks again

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  • STL: writing "where" operator for a vector.

    - by Arman
    Hello, I need to find the indexes in the vector based on several boolean predicates. ex: vector<float> v; vector<int> idx; idx=where( bool_func1(v), bool_func2(v), ... ); What is the way to declare **where** function, in order to use the several user defined boolean functions over the vector? thanks Arman.

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  • how can i get rotation vector from matrix4x4 in xna?

    - by mr.Smyle
    i want to get rotation vector from matrix to realize some parent-children system for models. Matrix bonePos = link.Bone.Transform * World; Matrix m = Matrix.CreateTranslation(link.Offset) * Matrix.CreateScale(link.gameObj.Scale.X, link.gameObj.Scale.Y, link.gameObj.Scale.Z) * Matrix.CreateFromYawPitchRoll(MathHelper.ToRadians(link.gameObj.Rotation.Y), MathHelper.ToRadians(link.gameObj.Rotation.X), MathHelper.ToRadians(link.gameObj.Rotation.Z)) //need rotation vector from bone matrix here (now it's global model rotation vector) * Matrix.CreateFromYawPitchRoll(MathHelper.ToRadians(Rotation.Y), MathHelper.ToRadians(Rotation.X), MathHelper.ToRadians(Rotation.Z)) * Matrix.CreateTranslation(bonePos.Translation); link.gameObj.World = m; where : link - struct with children model settings, like position, rotation etc. And link.Bone - Parent Bone

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  • What Java class should I use to represent a Vector?

    - by user8363
    Does Java have a built-in Vector class suitable for handling collision detection / response? It should have methods like subtract(Vector v), normalize(), dotProduct(Vector v), ... It seems logical to use java.awt.Rectangle and java.awt.Polygon to calculate collisions. Would I be right to use these classes for this purpose? I understand collision detection; I'm only wondering what approach to it is idiomatic in Java. I'm new to the language and to application development in general.

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  • How do I find a unit vector of another in Java?

    - by Shijima
    I'm writing a Java formula based on this tutorial: 2-D elastic collisions without Trigonometry. I am in the section "Elastic Collisions in 2 Dimensions". Part of step 1 says: Next, find the unit vector of n, which we will call un. This is done by dividing by the magnitude of n. My below code represents the normal vector of 2 objects (I'm using a simple array to represent the normal vector). int[] normal = new int[2]; normal[0] = ball2.x - ball1.x; normal[1] = ball2.y - ball1.y; I am unsure what the tutorial means by dividing the magnitude of n to get the un. What is un? How can I calculate it with my Java array?

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  • boost fusion: strange problem depending on number of elements on a vector

    - by ChAoS
    I am trying to use Boost::Fusion (Boost v1.42.0) in a personal project. I get an interesting error with this code: #include "boost/fusion/include/sequence.hpp" #include "boost/fusion/include/make_vector.hpp" #include "boost/fusion/include/insert.hpp" #include "boost/fusion/include/invoke_procedure.hpp" #include "boost/fusion/include/make_vector.hpp" #include <iostream> class Class1 { public: typedef boost::fusion::vector<int,float,float,char,int,int> SequenceType; SequenceType s; Class1(SequenceType v):s(v){} }; class Class2 { public: Class2(){} void met(int a,float b ,float c ,char d ,int e,int f) { std::cout << a << " " << b << " " << c << " " << d << " " << e << std::endl; } }; int main(int argn, char**) { Class2 p; Class1 t(boost::fusion::make_vector(9,7.66f,8.99f,'s',7,6)); boost::fusion::begin(t.s); //OK boost::fusion::insert(t.s, boost::fusion::begin(t.s), &p); //OK boost::fusion::invoke_procedure(&Class2::met,boost::fusion::insert(t.s, boost::fusion::begin(t.s), &p)); //FAILS } It fails to compile (gcc 4.4.1): In file included from /home/thechaos/Escriptori/of_preRelease_v0061_linux_FAT/addons/ofxTableGestures/ext/boost/fusion/include/invoke_procedur e.hpp:10, from problema concepte.cpp:11: /home/thechaos/Escriptori/of_preRelease_v0061_linux_FAT/addons/ofxTableGestures/ext/boost/fusion/functional/invocation/invoke_procedure.hpp: I n function ‘void boost::fusion::invoke_procedure(Function, const Sequence&) [with Function = void (Class2::*)(int, float, float, char, int, in t), Sequence = boost::fusion::joint_view<boost::fusion::joint_view<boost::fusion::iterator_range<boost::fusion::vector_iterator<const boost::f usion::vector<int, float, float, char, int, int, boost::fusion::void_, boost::fusion::void_, boost::fusion::void_, boost::fusion::void_>, 0>, boost::fusion::vector_iterator<boost::fusion::vector<int, float, float, char, int, int, boost::fusion::void_, boost::fusion::void_, boost::fus ion::void_, boost::fusion::void_>, 0> >, const boost::fusion::single_view<Class2*> >, boost::fusion::iterator_range<boost::fusion::vector_iter ator<boost::fusion::vector<int, float, float, char, int, int, boost::fusion::void_, boost::fusion::void_, boost::fusion::void_, boost::fusion: :void_>, 0>, boost::fusion::vector_iterator<const boost::fusion::vector<int, float, float, char, int, int, boost::fusion::void_, boost::fusion ::void_, boost::fusion::void_, boost::fusion::void_>, 6> > >]’: problema concepte.cpp:39: instantiated from here /home/thechaos/Escriptori/of_preRelease_v0061_linux_FAT/addons/ofxTableGestures/ext/boost/fusion/functional/invocation/invoke_procedure.hpp:88 : error: incomplete type ‘boost::fusion::detail::invoke_procedure_impl<void (Class2::*)(int, float, float, char, int, int), const boost::fusio n::joint_view<boost::fusion::joint_view<boost::fusion::iterator_range<boost::fusion::vector_iterator<const boost::fusion::vector<int, float, f loat, char, int, int, boost::fusion::void_, boost::fusion::void_, boost::fusion::void_, boost::fusion::void_>, 0>, boost::fusion::vector_itera tor<boost::fusion::vector<int, float, float, char, int, int, boost::fusion::void_, boost::fusion::void_, boost::fusion::void_, boost::fusion:: void_>, 0> >, const boost::fusion::single_view<Class2*> >, boost::fusion::iterator_range<boost::fusion::vector_iterator<boost::fusion::vector< int, float, float, char, int, int, boost::fusion::void_, boost::fusion::void_, boost::fusion::void_, boost::fusion::void_>, 0>, boost::fusion: :vector_iterator<const boost::fusion::vector<int, float, float, char, int, int, boost::fusion::void_, boost::fusion::void_, boost::fusion::voi d_, boost::fusion::void_>, 6> > >, 7, true, false>’ used in nested name specifier However, if I change the number of arguments in the vectors and the method from 6 to 5 from int,float,float,char,int,int to int,float,float,char,int,I can compile it without problems. I suspected about the maximum number of arguments being a limitation, but I tried to change it through defining FUSION_MAX_VECTOR_SIZE without success. I am unable to see what am I doing wrong. Can you reproduce this? Can it be a boost bug (i doubt it but is not impossible)?

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  • Pushing a variable onto a vector, value at that point in vector changes when the variable does.

    - by David Andrews
    I have a programming problem =) std::vector<char*> Names; if(MyPacket.ID == 3) {Names.push_back(MyPacket.Buffer);} I push the recieved buffer onto a vector like so, but when the buffer changes so does the value of the variable at that point in the vector. So say I sent and pushed a buffer containing 'Simon' onto the vector that would be fine so at point [0] on the vector would be the word Simon. but then when I recieve a new buffer it overwrites position [0] even though the packets ID is different, a breakpoint within the if statement is not reached with this new buffer. I really hope i'm explaining this well enough, I tried asking a friends advice and he pointed me towards this site. Any help appreciated David Andrews

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  • Extract co-ordinates from a vector of co-ordinates and save to file

    - by barsil sil
    I have a vector which contains a list co-ordinates ...x1,y1 ; x2,y2....xn,yn I am trying to extract each individual element which is a co-ordinate and then save them to file as a nice delineated co-ord pair which can be easily read. Or what would be nice i to save them so I can plot something in excel e.t.c (as cols of x and y values). My original vector size is 31, and was originally constructed as vector<vector<Point> > myvector( previous vector.size() ); Thanks !

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  • Extracting a reference from a c++ vector

    - by Archanimus
    Hello folks, I have a vector< vector< vector< int and I would like to extract from it a vector< vector< int to process it individually. The problem is that when I write : myMatrix = myCube[anIndex]; the matrix is copied but I only want a reference in order to save memory. Can you please help me out ? Thanks a lot!

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  • STL: how to overload operator= for <vector> ?

    - by MBes
    There's simple example: #include <vector> int main() { vector<int> veci; vector<double> vecd; for(int i = 0;i<10;++i){ veci.push_back(i); vecd.push_back(i); } vecd = veci; // <- THE PROBLEM } The thing I need to know is how to overload operator = so that I could make assignment like this: vector<double> = vector<int>; I've just tried a lot of ways, but always compiler has been returning errors... Is there any option to make this code work without changing it? I can write some additional lines, but can't edit or delete the existing ones. Ty.

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  • creating a vector with references to some of the elements of another vector

    - by memC
    hi, I have stored instances of class A in a std:vector, vec_A as vec_A.push_back(A(i)). The code is shown below. Now, I want to store references some of the instances of class A (in vec_A) in another vector or another array. For example, if the A.getNumber() returns 4, 7, 2 , I want to put a reference to that instance of A in another vector, say std:vector<A*> filtered_A or an array. Can someone sow me how to do this?? Thanks! class A { public: int getNumber(); A(int val); ~A(){}; private: int num; }; A::A(int val){ num = val; }; int A::getNumber(){ return num; }; int main(){ int i =0; int num; std::vector<A> vec_A; for ( i = 0; i < 10; i++){ vec_A.push_back(A(i)); } std::cout << "\nPress RETURN to continue..."; std::cin.get(); return 0; }

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  • Pushing an array into a vector.

    - by Sunil
    I've a 2d array, say A[2][3]={{1,2,3},{4,5,6}}; and I want to push it into a 2D vector(vector of vectors). I know you can use two for loops to push the elements one by on on to the first vector and then push that into the another vector which makes it 2d vector but I was wondering if there is any way in C++ to do this in a single loop. For example I want to do something like this: myvector.pushback(A[1]+3); // where 3 is the size or number of columns in the array. I understand this is not a correct code but I put this just for understanding purpose. Thanks

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  • How to update a vector in method

    - by gurpinars
    I'm new to C++ and trying to understand vectors. My goal is to update a vector in method: #include <vector> #include <iostream> using namespace std; void test(vector<int>& array){ for(int i=0;i<10;i++){ array.push_back(i); } } int main(){ // some integer value vector<int> array(10); test(array); for(int i=0;i<array.size();++i) cout<<array.at(i)<<endl; cout<<"array size:"<<array.size()<<endl; return 0; } output: 0 0 0 0 0 0 0 0 0 0 0 1 2 3 4 5 6 7 8 9 array size:20 I haven't figure out why 10 zeros add vector at first?

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  • C++ Reference of vector

    - by void
    Hello, class Refvect { public: vector<int> &refv; Refvect(int t, vector<int> &refv = vector<int>()) : refv(refv) { }; void operator()() { refv.clear(); } }; int main () { Refvect r(0); r(); } With Visual Studio 2010, this gives me an error : "vector iterators incompatible" at the execution, but I don't understand why (but I can insert elements in refv without any problem). The temporary object vector() lives as long as the reference, no?

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  • JavaScript or PHP based WYSIWYG vector based image editor

    - by Jeroen Pluimers
    For a PHP based site of a client, I'm looking for a vector based image editor that allows: end user creation of vectored images consisting of objects supports upload of bitmap images to be used as objects inside the vector image supports adding text objects to add to the vector image, and change properties (font name, font style, font size) of the text objects preferably supports layering or grouping of objects inside the vector image integrates nicely with a PHP based site (so a PHP or JavaScript library is preferred) can store the vector image in SVG, EPS or PDF Both commercial and FOSS solutions are OK. Any idea where to find such a library? --jeroen

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