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  • std::vector iterator or index access speed question

    - by Simone Margaritelli
    Just a stupid question . I have a std::vector<SomeClass *> v; in my code and i need to access its elements very often in the program, looping them forward and backward . Which is the fastest access type between those two ? Iterator access std::vector<SomeClass *> v; std::vector<SomeClass *>::iterator i; std::vector<SomeClass *>::reverse_iterator j; // i loops forward, j loops backward for( i = v.begin(), j = v.rbegin(); i != v.end() && j != v.rend(); i++, j++ ){ // some operations on v items } Subscript access (by index) std::vector<SomeClass *> v; unsigned int i, j, size = v.size(); // i loops forward, j loops backward for( i = 0, j = size - 1; i < size && j >= 0; i++, j-- ){ // some operations on v items } And, does const_iterator offer a faster way to access vector elements in case i do not have to modify them? Thank you in advantage.

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  • How to print all values of Vector[]

    - by terence6
    I have a Vector[] of Object type that stores my data. How to print all it's objects ? The code: private static Vector<Object[]> vector = new Vector<Object[]>(); int event=0; for(int i=0; i<10; i++){ vector.add( this.addToObject(System.currentTimeMillis(), event , "String") ); event++; } private Object[] addToObject(long t, int i,String s ){ Object[] o = new Object[4]; o[3] = s; o[2] = i; o[1] = "00000"; o[0] = t; return o; } printing public static void main(String[]args){ main m = new Main(); for(int i=0; i< m.vector.size(); i++){ } } And I'd like to get sth like this : 1202393057117 1 OOOOO String 1202393057117 2 OOOOO String 1202393057118 3 OOOOO String 1202393057118 4 OOOOO String 1202393057118 5 OOOOO String

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  • iterators to range of elements in a vector whose attributes have specific value

    - by user1801173
    I have a vector of objects and I want to return the range of elements whose attribute have a specific value. This is the structure: class A { public: std::vector<B*> vec_; pair<vector<B*>::iterator, vector<B*>::iterator> getElements(unsigned int attr_val); unsigned int name() { return name_; } private: unsigned int name_; }; class B { public: unsigned int attr() { return attr_; } A* source() { return source_; } B* dest() { return dest_; } private: A* source_; B* dest_; unsigned int attr_; }; The vector vec_; is already sorted by attr_ and dest_-name() (in that order). Now I want to return all elements, whose attr_ is equal to attr_val. What is the appropriate stl algorithm (or is there even a vector member function?) to implement getElements(unsigned int attr_val) ? Thanks for help.

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  • velocity vector

    - by wanderer
    Hi, I am trying to simulate a collision. The collision is shown here http://www.freeimagehosting.net/image.php?c5ae01b476.jpg A particle falls down on a sphere and a collision between sphere and particle takes place. The sphere always remain stationary and the collision itself is not elastic. So if the particle falls directly n top of sphere, the velocity of particle will become zero. I was trying to set the velocity of particle to be zero after the collision. But that does not give good simulation when the collision does not occur on top of sphere but along the side of sphere. So now after the collision i need to make sure that the particle has a velocity which is orthogonal to the vector of the point of collision from the center of sphere. The velocity along the vector from center of sphere to point of collision should become zero. How do i do that? I am a bit mathematically challenged but i think it has something to do with dot product of vectors. Or maybe i am wrong :) I have the initial velocity vector and 'radiusvector' say :- 1)velocity <-1.03054, -1.56563, 1.33341e-016 2) radius vector <2.04406, 2.19587, 1.0514 Pseudo code for the problem is: foreach( particle particle in particlesCollections) { //sphere.x, sphere.y sphere.z give the center of the sphere dist = particle.pos-vector(sphere.x,sphere.y,sphere.z); //detect if a collision has taken place. if (dist.mag < sphere.radius) { rVector=dist/dist.mag*sphere.radius; particle.pos=vector(sphere.x,sphere.y,sphere.z) + rVector; //particle.Velocity gives the velocity vector of the particle at the time of collision //i need to modify particle.Velocity so that the component of velocity that runs along // with the rvector becomes zero as i have a non elsatic collision. The remaining //velocity that the particle will have is the one which runs along with tangent to the //rVector. The sphere remains stationary. //example values: particle.Velocity == <-1.03054, -1.56563, .006> //and rVector = <2.04406, 2.19587, 1.0514> } } Thanks

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  • segfault on vector<struct>

    - by Andre
    Hello, I created a struct to hold some data and then declared a vector to hold that struct. But when I do a push_back I get damn segfault and I have no idea why! My struct is defines as: typedef struct Group { int codigo; string name; int deleted; int printers; int subpage; /*included this when it started segfaulting*/ Group(){ name.reserve(MAX_PRODUCT_LONG_NAME); } ~Group(){ name.clear(); } Group(const Group &b) { codigo = b.codigo; name = b.name; deleted = b.deleted; printers = b.printers; subpage = b.subpage; } /*end of new stuff*/ }; Originally, the struct didn't have the copy, constructor or destructor. I added them latter when I read this post below. http://stackoverflow.com/questions/676575/seg-fault-after-is-item-pushed-onto-stl-container but the end result is the same. There is one this that is bothering me as hell! When I first push some data into the vector, everything goes fine. Later on in the code when I try to push some more data into the vector, my app just segfaults! The vector is declared vector<Group> Groups and is a global variable to the file where I am using it. No externs anywhere else, etc... I can trace the error to: _M_deallocate(this->_M_impl._M_start, this->_M_impl._M_end_of_storage- this->_M_impl._M_start); in vector.tcc when I finish adding/copying the last element to the vector.... As far as I can tell. I shouldn't be needing anything to do with a copy constructor as a shallow copy should be enough for this. I'm not even allocating any space (but I did a reserve for the string to try out). I have no idea what the problem is! I'm running this code on OpenSuse 10.2 with gcc 4.1.2 I'm not really to eager to upgrade gcc because of backward compatibility issues... This code worked "perfectly" on my windows machine. I compiled it with gcc 3.4.5 mingw without any problems... help! --- ... --- :::EDIT::: I push data Group tmp_grp; (...) tmp_grp.name = "Nova "; tmp_grp.codigo=GetGroupnextcode(); tmp_grp.deleted=0; tmp_grp.printers=0; tmp_grp.subpage=0; Groups.push_back(tmp_grp);

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  • C++ vector pointer/reference problem

    - by sub
    Please take a look at this example: #include <iostream> #include <vector> #include <string> using namespace std; class mySubContainer { public: string val; }; class myMainContainer { public: mySubContainer sub; }; void doSomethingWith( myMainContainer &container ) { container.sub.val = "I was modified"; } int main( ) { vector<myMainContainer> vec; /** * Add test data */ myMainContainer tempInst; tempInst.sub.val = "foo"; vec.push_back( tempInst ); tempInst.sub.val = "bar"; vec.push_back( tempInst ); // 1000 lines of random code here int i; int size = vec.size( ); myMainContainer current; for( i = 0; i < size; i ++ ) { cout << i << ": Value before='" << vec.at( i ).sub.val << "'" << endl; current = vec.at( i ); doSomethingWith( current ); cout << i << ": Value after='" << vec.at( i ).sub.val << "'" << endl; } system("pause");//i suck } A hell lot of code for an example, I know. Now so you don't have to spend years thinking about what this [should] do[es]: I have a class myMainContainer which has as its only member an instance of mySubContainer. mySubContainer only has a string val as member. So I create a vector and fill it with some sample data. Now, what I want to do is: Iterate through the vector and make a separate function able to modify the current myMainContainer in the vector. However, the vector remains unchanged as the output tells: 0: Value before='foo' 0: Value after='foo' 1: Value before='bar' 1: Value after='bar' What am I doing wrong? doSomethingWith has to return void, I can't let it return the modified myMainContainer and then just overwrite it in the vector, that's why I tried to pass it by reference as seen in the doSomethingWith definition above.

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  • overloaded stream insertion operator with a vector

    - by Julz
    hi, i'm trying to write an overloaded stream insertion operator for a class who's only member is a vector. i dont really know what i'm doing. (lets make that clear) it's a vector of "Points" which is a struct containing two doubles. i figure what i want is to insert user input (a bunch of doubles) into a stream that i then send to a modifier method? i keep working off other stream insertion examples such as... std::ostream& operator<< (std::ostream& o, Fred const& fred) { return o << fred.i_; } but when i try a similar..... istream & operator >> (istream &inStream, Polygon &vertStr) { inStream >> ws; inStream >> vertStr.vertices; return inStream; } i get an error "no match for operator etc etc. if i leave off the .vertices it compiles but i figure it's not right? (vertices is the name of my vector ) and even if it is right, i dont actually know what syntax to use in my driver to use it? also not %100 on what my modifier method needs to look like. here's my Polygon class //header #ifndef POLYGON_H #define POLYGON_H #include "Segment.h" #include <vector> class Polygon { friend std::istream & operator >> (std::istream &inStream, Polygon &vertStr); public: //Constructor Polygon(const 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 (int) vertices.capacity();} //add Point elements to vector inline void setVertices(const Point &theVerts){vertices.push_back (theVerts);} private: std::vector<Point> vertices; }; #endif //Body using namespace std; #include "Polygon.h" // Constructor Polygon::Polygon(const Point &theVerts) { vertices.push_back (theVerts); } //Copy Constructor Polygon::Polygon(const Polygon &polyCopy) { vertices = polyCopy.vertices; } //Default Constructor Polygon::Polygon(){} istream & operator >> (istream &inStream, Polygon &vertStr) { inStream >> ws; inStream >> vertStr; return inStream; } any help greatly appreciated, sorry to be so vague, a lecturer has just kind of given us a brief example of stream insertion then left us on our own thanks. oh i realise there are probably many other problems that need fixing

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  • overloaded stream insetion operator with a vector

    - by julz666
    hi, i'm trying to write an overloaded stream insertion operator for a class who's only member is a vector. i dont really know what i'm doing. (lets make that clear) it's a vector of "Points" which is a struct containing two doubles. i figure what i want is to insert user input (a bunch of doubles) into a stream that i then send to a modifier method? i keep working off other stream insertion examples such as... std::ostream& operator<< (std::ostream& o, Fred const& fred) { return o << fred.i_; } but when i try a similar..... istream & operator >> (istream &inStream, Polygon &vertStr) { inStream >> ws; inStream >> vertStr.vertices; return inStream; } i get an error "no match for operator etc etc. if i leave off the .vertices it compiles but i figure it's not right? (vertices is the name of my vector ) and even if it is right, i dont actually know what syntax to use in my driver to use it? also not %100 on what my modifier method needs to look like. here's my Polygon class //header #ifndef POLYGON_H #define POLYGON_H #include "Segment.h" #include <vector> class Polygon { friend std::istream & operator >> (std::istream &inStream, Polygon &vertStr); public: //Constructor Polygon(const 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 (int) vertices.capacity();} //add Point elements to vector inline void setVertices(const Point &theVerts){vertices.push_back (theVerts);} private: std::vector<Point> vertices; }; #endif //Body using namespace std; #include "Polygon.h" // Constructor Polygon::Polygon(const Point &theVerts) { vertices.push_back (theVerts); } //Copy Constructor Polygon::Polygon(const Polygon &polyCopy) { vertices = polyCopy.vertices; } //Default Constructor Polygon::Polygon(){} istream & operator >> (istream &inStream, Polygon &vertStr) { inStream >> ws; inStream >> vertStr; return inStream; } any help greatly appreciated, sorry to be so vague, a lecturer has just kind of given us a brief example of stream insertion then left us on our own thanks. oh i realise there are probably many other problems that need fixing

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  • STL vector reserve() and copy()

    - by natersoz
    Greetings, I am trying to perform a copy from one vector (vec1) to another vector (vec2) using the following 2 abbreviated lines of code (full test app follows): vec2.reserve( vec1.size() ); copy(vec1.begin(), vec1.end(), vec2.begin()); While the call to vec2 sets the capacity of vector vec2, the copying of data to vec2 seems to not fill in the values from vec1 to vec2. Replacing the copy() function with calls to push_back() works as expected. What am I missing here? Thanks for your help. vectest.cpp test program followed by resulting output follows. Compiler: gcc 3.4.4 on cygwin. Nat /** * vectest.cpp */ #include <iostream> #include <vector> using namespace std; int main() { vector<int> vec1; vector<int> vec2; vec1.push_back(1); vec1.push_back(2); vec1.push_back(3); vec1.push_back(4); vec1.push_back(5); vec1.push_back(6); vec1.push_back(7); vec2.reserve( vec1.size() ); copy(vec1.begin(), vec1.end(), vec2.begin()); cout << "vec1.size() = " << vec1.size() << endl; cout << "vec1.capacity() = " << vec1.capacity() << endl; cout << "vec1: "; for( vector<int>::const_iterator iter = vec1.begin(); iter < vec1.end(); ++iter ) { cout << *iter << " "; } cout << endl; cout << "vec2.size() = " << vec2.size() << endl; cout << "vec2.capacity() = " << vec2.capacity() << endl; cout << "vec2: "; for( vector<int>::const_iterator iter = vec2.begin(); iter < vec2.end(); ++iter ) { cout << *iter << endl; } cout << endl; } output: vec1.size() = 7 vec1.capacity() = 8 vec1: 1 2 3 4 5 6 7 vec2.size() = 0 vec2.capacity() = 7 vec2:

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  • Rendering a big game universe - bitmaps or vector graphics?

    - by user1641923
    I am new to an Android development, though I have much experience with Java, C++, PHP programming and a bit experience with vector graphics too (basic 3d Studio Max, Flash, etc). I am starting to work on an Android game. It is going to be a 2D space shooter/RPG, and I am not going to use any game engines and any 3D party libs. I really want to create a very large game universe, or even pseudo-infinite (without visible borders, as if it were a 2D projection of a sphere). It should include 10-12 clusters of 7-8 planets/other space objects and random amount of single asteroids/comets, which player can interact with and also not interactive background. I am looking for a least complicated aproach to create such a universe. My current ideas are: Simply create bitmaps with space scenery background so that they can be tiled seamlessly repeated and construct my 2D universe of this tiles, then place interactive objects (planets, other spaceships) on it. Using vector graphics. I would have a solid color background, some random background objects and gradients here and there. My problems here: Lack of knowledge of how well vector graphics is integrated in Android. Performance? Memory usage? Does Android manage big bitmaps well? Do all of the bitmaps have to be in memory during all game process? I am interested in technical details regarding each of the ideas and a suggestion, which I should go with.

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  • Vector is pointing to uninitialized bytes when used in recvfrom call

    - by Adam A.
    In a function that I am writing I am trying to return a pointer to a vector of unsigned chars. The relevant code is below. std::vector<unsigned char> *ret = new std::vector<unsigned char>(buffSize,'0'); int n = recvfrom(fd_, &((*ret)[0]) ,buffSize, &recvAddress, &sockSize); //This should work too... recvfrom(fd_, ret ,buffSize, &recvAddress, &sockSize); // display chars somehow just for testing for(std::vector<unsigned char>::iterator it=ret->begin(); it<it->end();i++) { std::cout<<*it; } std::cout<<std::endl; ... return ret; When I run this through valgrind I get errors talking about how the buffer in recvfrom is pointing to uninitialized bytes. I've narrowed this down to the vector since I swapped it out for an unsigned char array and everything works fine. Any suggestions?

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  • AS3 serialization of Vector of custom objects

    - by aaaidan
    What is serialization support like for the new Vector class. I have a Vector.<GameMove> which I'd like to serialize into a ByteArray. GameMove is a custom class. I presume it's necesssary to call registerClassAlias() on GameMove, but do I also have to register Vector.<GameMove>? It's it it's own distinctive type, or is it kinda composed of those two types?

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  • vector::erase with pointer member

    - by matt
    I am manipulating vectors of objects defined as follow: class Hyp{ public: int x; int y; double wFactor; double hFactor; char shapeNum; double* visibleShape; int xmin, xmax, ymin, ymax; Hyp(int xx, int yy, double ww, double hh, char s): x(xx), y(yy), wFactor(ww), hFactor(hh), shapeNum(s) {visibleShape=0;shapeNum=-1;}; //Copy constructor necessary for support of vector::push_back() with visibleShape Hyp(const Hyp &other) { x = other.x; y = other.y; wFactor = other.wFactor; hFactor = other.hFactor; shapeNum = other.shapeNum; xmin = other.xmin; xmax = other.xmax; ymin = other.ymin; ymax = other.ymax; int visShapeSize = (xmax-xmin+1)*(ymax-ymin+1); visibleShape = new double[visShapeSize]; for (int ind=0; ind<visShapeSize; ind++) { visibleShape[ind] = other.visibleShape[ind]; } }; ~Hyp(){delete[] visibleShape;}; }; When I create a Hyp object, allocate/write memory to visibleShape and add the object to a vector with vector::push_back, everything works as expected: the data pointed by visibleShape is copied using the copy-constructor. But when I use vector::erase to remove a Hyp from the vector, the other elements are moved correctly EXCEPT the pointer members visibleShape that are now pointing to wrong addresses! How to avoid this problem? Am I missing something?

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  • C# Vector maths questions

    - by Mark
    Im working in a screen coordinate space that is different to that of the classical X/Y coordinate space, where my Y direction goes down in the positive instead of up. Im also trying to figure out how to make a Circle on my screen always face away from the center point of the screen. If the center point of my screen is at x(200) y(300) and the point of my circle's center is at x(150) and y(380) then I would like to calculate the angle that the circle should be facing. At the moment I have this: Point centerPoint = new Point(200, 300); Point middleBottom = new Point(200, 400); Vector middleVector = new Vector(centerPoint.X - middleBottom.X, centerPoint.Y - middleBottom.Y); Vector vectorOfCircle = new Vector(centerPoint.X - 150, centerPoint.Y - 400); middleVector.Normalize(); vectorOfCircle.Normalize(); var angle = Math.Acos(Vector.CrossProduct(vectorOfCircle, middleVector)); Console.WriteLine("Angle: {0}", angle * (180/Math.PI)); Im not getting what I would expect. I would say that when I enter in x(150) and y(300) of my circle, I would expect to see the rotation of 90 deg, but Im not getting that... Im getting 180!! Any help here would be greatly appreciated. Cheers, Mark

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  • Using read() directly into a C++ std:vector

    - by Joe
    I'm wrapping up user space linux socket functionality in some C++ for an embedded system (yes, this is probably reinventing the wheel again). I want to offer a read and write implementation using a vector. Doing the write is pretty easy, I can just pass &myvec[0] and avoid unnecessary copying. I'd like to do the same and read directly into a vector, rather than reading into a char buffer then copying all that into a newly created vector. Now, I know how much data I want to read, and I can allocate appropriately (vec.reserve). I can also read into &myvec[0], though this is probably a VERY BAD IDEA. Obviously doing this doesn't allow myvec.size to return anything sensible. Is there any way of doing this that 1) Doesn't completely feel yucky from a safety/C++ perspective and 2) Doesn't involve two copies of the data block - once from kernel to user space and once from a C char * style buffer into a C++ vector. Any thoughts collective?

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  • C++ Operator overloading - 'recreating the Vector'

    - by Wallter
    I am currently in a collage second level programing course... We are working on operator overloading... to do this we are to rebuild the vector class... I was building the class and found that most of it is based on the [] operator. When I was trying to implement the + operator I run into a weird error that my professor has not seen before (apparently since the class switched IDE's from MinGW to VS express...) (I am using Visual Studio Express 2008 C++ edition...) Vector.h #include <string> #include <iostream> using namespace std; #ifndef _VECTOR_H #define _VECTOR_H const int DEFAULT_VECTOR_SIZE = 5; class Vector { private: int * data; int size; int comp; public: inline Vector (int Comp = 5,int Size = 0) : comp(Comp), size(Size) { if (comp > 0) { data = new int [comp]; } else { data = new int [DEFAULT_VECTOR_SIZE]; comp = DEFAULT_VECTOR_SIZE; } } int size_ () const { return size; } int comp_ () const { return comp; } bool push_back (int); bool push_front (int); void expand (); void expand (int); void clear (); const string at (int); int operator[ ](int); Vector& operator+ (Vector&); Vector& operator- (const Vector&); bool operator== (const Vector&); bool operator!= (const Vector&); ~Vector() { delete [] data; } }; ostream& operator<< (ostream&, const Vector&); #endif Vector.cpp #include <iostream> #include <string> #include "Vector.h" using namespace std; const string Vector::at(int i) { this[i]; } void Vector::expand() { expand(size); } void Vector::expand(int n ) { int * newdata = new int [comp * 2]; if (*data != NULL) { for (int i = 0; i <= (comp); i++) { newdata[i] = data[i]; } newdata -= comp; comp += n; delete [] data; *data = *newdata; } else if ( *data == NULL || comp == 0) { data = new int [DEFAULT_VECTOR_SIZE]; comp = DEFAULT_VECTOR_SIZE; size = 0; } } bool Vector::push_back(int n) { if (comp = 0) { expand(); } for (int k = 0; k != 2; k++) { if ( size != comp ){ data[size] = n; size++; return true; } else { expand(); } } return false; } void Vector::clear() { delete [] data; comp = 0; size = 0; } int Vector::operator[] (int place) { return (data[place]); } Vector& Vector::operator+ (Vector& n) { int temp_int = 0; if (size > n.size_() || size == n.size_()) { temp_int = size; } else if (size < n.size_()) { temp_int = n.size_(); } Vector newone(temp_int); int temp_2_int = 0; for ( int j = 0; j <= temp_int && j <= n.size_() && j <= size; j++) { temp_2_int = n[j] + data[j]; newone[j] = temp_2_int; } //////////////////////////////////////////////////////////// return newone; //////////////////////////////////////////////////////////// } ostream& operator<< (ostream& out, const Vector& n) { for (int i = 0; i <= n.size_(); i++) { //////////////////////////////////////////////////////////// out << n[i] << " "; //////////////////////////////////////////////////////////// } return out; } Errors: out << n[i] << " "; error C2678: binary '[' : no operator found which takes a left-hand operand of type 'const Vector' (or there is no acceptable conversion) return newone; error C2106: '=' : left operand must be l-value As stated above, I am a student going into Computer Science as my selected major I would appreciate tips, pointers, and better ways to do stuff :D

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  • c++ : list(vector) definition with array

    - by Meloun
    I have Class Email, there is parameter "bcc" in her construktor. Its actually list of emails for copies. There is no fixed number of these emails and later i have to have possibility to extend this list. //construktor prototype Email::Email(vector<string> bcc) So i want to use type vector or list for that and function push_back(). How can i make a new instance with bcc emails? I need actually declaration with definition for my list. I've found this definition with iterator for integer type: int myints[] = {16,2,77,29}; Email myEmail(vector<int> (myints, myints + sizeof(myints) / sizeof(int) )); , but its not very user friend and i need it with strings. Is there something like this? Email myEmail(vector<string> ("first","second","third"));

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  • How to call a method withgin a vector?

    - by Mike Dooley
    Hi! How do I call a method of an object which is stored within a vector? The following code fails... ClassA* class_derived_a = new ClassDerivedA; ClassA* class_another_a = new ClassAnotherDerivedA; vector<ClassA*> test_vector; test_vector.push_back(class_derived_a); test_vector.push_back(class_another_a); for (vector<ClassA*>::iterator it = test_vector.begin(); it != test_vector.end(); it++) it->printOutput(); The code retrieves the following error: test3.cpp:47: error: request for member ‘printOutput’ in ‘* it.__gnu_cxx::__normal_iterator<_Iterator, _Container::operator- with _Iterator = ClassA**, _Container = std::vector ’, which is of non-class type ‘ClassA*’ The problem seems to be it->printOutput(); but at the moment I don't know how to call the method properly, does anyone know? regards mikey

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  • Using std::ifstream to load in an array of struct data type into a std::vector

    - by Sent1nel
    I am working on a bitmap loader in C++ and when moving from the C style array to the std::vector I have run into an usual problem of which Google does not seem to have the answer. 8 Bit and 4 bit, bitmaps contain a colour palette. The colour palette has blue, green, red and reserved components each 1 byte in size. // Colour palette struct BGRQuad { UInt8 blue; UInt8 green; UInt8 red; UInt8 reserved; }; The problem I am having is when I create a vector of the BGRQuad structure I can no longer use the ifstream read function to load data from the file directly into the BGRQuad vector. // This code throws an assert failure! std::vecotr quads; if (coloursUsed) // colour table available { // read in the colours quads.reserve(coloursUsed); inFile.read( reinterpret_cast(&quads[0]), coloursUsed * sizeof(BGRQuad) ); } Does anyone know how to read directly into the vector without having to create a C array and copy data into the BGRQuad vector?

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  • Finding if all elements in a vector<string> are in a string

    - by devin
    I have a vector and I need to see if all the strings in that vector are substrings of another given string. eg vector<string> v; v.push_back("str1"); v.push_back("str2"); string s1 = "str1, str2, str3"; string s2 = "str1, str3"; Is there a way to get true from s1 and false from s2 without looping over the vector? Also, note that due to my environment, I can't use boost. I think if I had boost, I could do this.

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  • "Right" way to deallocate an std::vector object

    - by Jacob
    The first solution is: std::vector<int> *vec = new std::vector<int>; assert(vec != NULL); // ... delete vec; An alternative is: std::vector<int> v; //... vec.clear(); vec.swap(std::vector<int>(vec)); The second solution's a bit of a trick --- what's the "right" way to do it?

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  • Vector does reallocation on every push_back

    - by Amrish
    IDE - Visual Studio 2008, Visual C++ I have a custom class Class1 with a copy constructor to it. I also have a vector Data is inserted using the following code Class1* objClass1; vector<Class1> vClass1; for(int i=0;i<1000;i++) { objClass1 = new Class1(); vClass1.push_back(*objClass1); delete objClass1; } Now on every insert, the vector gets re-allocated and all the existing contents are copied to new locations. For example, if the vector has 5 elements and if I insert the 6th one, the previous 5 elements along with the new one gets copied to a new location (I figured it out by adding log statements in the copy constructors.) On using reserve(), this however does not happen as expected! I have the following questions Is it mandatory to always use the reserve statement? Does vector does a reallocation every time I do a push_back; or does it happen because I am debugging?

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