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  • Vector transform equation explanation

    - by cyberdemon
    I'm trying to understand the maths of moving points in a 3d space by making a game written in C#. I'm looking at this wolfire blog series which explains some basic 3d maths. I've read the first two parts but am stuck on the 3rd. I know it's all really rudimentary stuff but I find Googling for help with equations really hard. The one I'm struggling with is: 0*(0.66,0.75) + 2*(-0.75, 0.66) = (-1.5, 1.3) How can anything multiplied by 0 not be 0? So my question is how does this look in code: x(a,b) + y(c,d) I know it's basic stuff but I just can't see it.

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  • std::vector elements initializing

    - by Chameleon
    std::vector<int> v1(1000); std::vector<std::vector<int>> v2(1000); std::vector<std::vector<int>::const_iterator> v3(1000); How elements of these 3 vectors initialized? About int, I test it and I saw that all elements become 0. Is this standard? I believed that primitives remain undefined. I create a vector with 300000000 elements, give non-zero values, delete it and recreate it, to avoid OS memory clear for data safety. Elements of recreated vector were 0 too. What about iterator? Is there a initial value (0) for default constructor or initial value remains undefined? When I check this, iterators point to 0, but this can be OS When I create a special object to track constructors, I saw that for first object, vector run the default constructor and for all others it run the copy constructor. Is this standard? Is there a way to completely avoid initialization of elements? Or I must create my own vector? (Oh my God, I always say NOT ANOTHER VECTOR IMPLEMENTATION) I ask because I use ultra huge sparse matrices with parallel processing, so I cannot use push_back() and of course I don't want useless initialization, when later I will change the value.

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  • Cast vector<T> to vector<const T>

    - by user345386
    I have a member variable of type vector (where is T is a custom class, but it could be int as well.) I have a function from which I want to return a pointer to this vector, but I don't want the caller to be able to change the vector or it's items. So I want the return type to be const vector* None of the casting methods I tried worked. The compiler keeps complaining that T is not compatible with const T. Here's some code that demonstrates the gist of what I'm trying to do; vector<int> a; const vector<const int>* b = (const vector<const int>* ) (&a); This code doesn't compile for me. Thanks in advance!

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  • Would vector of vectors be contiguous?

    - by user1150989
    I need to allocate a vector of rows where row contains a vector of rows. I know that a vector would be contiguous. I wanted to know whether a vector of vectors would also be contiguous. Example code is given below vector<long> firstRow; firstRow.push_back(0); firstRow.push_back(1); vector<long> secondRow; secondRow.push_back(0); secondRow.push_back(1); vector< vector < long> > data; data.push_back(firstRow); data.push_back(secondRow); Would the sequence in memory be 0 1 0 1?

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  • C++ vector reference parameter

    - by Archanimus
    Hello folks, let's say we have a class class MyClass { vector<vector<int > > myMatrice; public : MyClass(vector<vector<int > > &); } MyClass::MyClass(vector<vector<int > > & m) { myMatrice = m; } During the instanciation of MyClass, I pass a big vector < vector < int and I find that the object is actually copied and not only the reference, so it takes the double of the memory ... Please, can anyone help me out with this problem, I'm stuck since too many time ... And thanks a lot!

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  • Populate array from vector

    - by Zag zag..
    Hi, I would like to populate an 2 dimensional array, from a vector. I think the best way to explain myself is to put some examples (with a array of [3,5] length). When vector is: [1, 0] [ [4, 3, 2, 1, 0], [4, 3, 2, 1, 0], [4, 3, 2, 1, 0] ] When vector is: [-1, 0] [ [0, 1, 2, 3, 4], [0, 1, 2, 3, 4], [0, 1, 2, 3, 4] ] When vector is: [-2, 0] [ [0, 0, 1, 1, 2], [0, 0, 1, 1, 2], [0, 0, 1, 1, 2] ] When vector is: [1, 1] [ [2, 2, 2, 1, 0], [1, 1, 1, 1, 0], [0, 0, 0, 0, 0] ] When vector is: [0, 1] [ [2, 2, 2, 2, 2], [1, 1, 1, 1, 1], [0, 0, 0, 0, 0] ] Have you got any ideas, a good library or a plan? Any comments are welcome. Thanks. Note: I consulted Ruby "Matrix" and "Vector" classes, but I don't see any way to use it in my way... Edit: In fact, each value is the number of cells (from the current cell to the last cell) according to the given vector. If we take the example where the vector is [-2, 0], with the value *1* (at array[2, 3]): array = [ [<0>, <0>, <1>, <1>, <2>], [<0>, <0>, <1>, <1>, <2>], [<0>, <0>, <1>, *1*, <2>] ] ... we could think such as: The vector [-2, 0] means that -2 is for cols and 0 is for rows. So if we are in array[2, 3], we can move 1 time on the left (left because 2 is negative) with 2 length (because -2.abs == 2). And we don't move on the top or bottom, because of 0 for rows.

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  • How can I move a polygon edge 1 unit away from the center?

    - by Stephen
    Let's say I have a polygon class that is represented by a list of vector classes as vertices, like so: var Vector = function(x, y) { this.x = x; this.y = y; }, Polygon = function(vectors) { this.vertices = vectors; }; Now I make a polygon (in this case, a square) like so: var poly = new Polygon([ new Vector(2, 2), new Vector(5, 2), new Vector(5, 5), new Vector(2, 5) ]); So, the top edge would be [poly.vertices[0], poly.vertices[1]]. I need to stretch this polygon by moving each edge away from the center of the polygon by one unit, along that edge's normal. The following example shows the first edge, the top, moved one unit up: The final polygon should look like this new one: var finalPoly = new Polygon([ new Vector(1, 1), new Vector(6, 1), new Vector(6, 6), new Vector(1, 6) ]); It is important that I iterate, moving one edge at a time, because I will be doing some collision tests after moving each edge. Here is what I tried so far (simplified for clarity), which fails triumphantly: for(var i = 0; i < vertices.length; i++) { var a = vertices[i], b = vertices[i + 1] || vertices[0]; // in case of final vertex var ax = a.x, ay = a.y, bx = b.x, by = b.y; // get some new perpendicular vectors var a2 = new Vector(-ay, ax), b2 = new Vector(-by, bx); // make into unit vectors a2.convertToUnitVector(); b2.convertToUnitVector(); // add the new vectors to the original ones a.add(a2); b.add(b2); // the rest of the code, collision tests, etc. } This makes my polygon start slowly rotating and sliding to the left, instead of what I need. Finally, the example shows a square, but the polygons in question could be anything. They will always be convex, and always with vertices in clockwise order.

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  • Looking for "bitmap-vector" image editor

    - by Borek
    I used to use PhotoImpact which is no longer developed so I'm looking for a replacement. What made PhotoImpact great to me was the ability to work in both bitmap and vector modes. What I mean by that: I could have an image or screenshot and easily add arrows, text captions or shapes to it. These shapes were vector objects so I could come back to them later and amend their properties easily. Software I know of: Paint.NET is purely bitmap so please don't recommend it - layers are not enough for my needs Drawing tools in MS Office work pretty much the way I'd like - you can paste an image and then add vector objects on top of it. It just doesn't feel right to have the full-fidelity original images stored as .docx or .pptx (I don't fully trust Word/Powerpoint that they don't compress the image) I'm not sure about GIMP but if it's just "better Paint.NET" (i.e., layers but no vector objects) I'm not interested Photoshop is out of question purely because of its price tag Corel killed PhotoImpact because they already had a competing product (Paint Shop Pro) but AFAIK it lacks vector features. Any tips for PhotoImpact alternatives would be very welcome.

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  • KD-Trees and missing values (vector comparison)

    - by labratmatt
    I have a system that stores vectors and allows a user to find the n most similar vectors to the user's query vector. That is, a user submits a vector (I call it a query vector) and my system spits out "here are the n most similar vectors." I generate the similar vectors using a KD-Tree and everything works well, but I want to do more. I want to present a list of the n most similar vectors even if the user doesn't submit a complete vector (a vector with missing values). That is, if a user submits a vector with three dimensions, I still want to find the n nearest vectors (stored vectors are of 11 dimensions) I have stored. I have a couple of obvious solutions, but I'm not sure either one seem very good: Create multiple KD-Trees each built using the most popular subset of dimensions a user will search for. That is, if a user submits a query vector of thee dimensions, x, y, z, I match that query to my already built KD-Tree which only contains vectors of three dimensions, x, y, z. Ignore KD-Trees when a user submits a query vector with missing values and compare the query vector to the vectors (stored in a table in a DB) one by one using something like a dot product. This has to be a common problem, any suggestions? Thanks for the help.

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  • Direct3D Rotation Matrix from Vector and vice-versa

    - by Beta Carotin
    I need to compute a rotation matrix from a direction vector, and a direction vector from a rotation matrix. The up direction should correspond to the z-axis, forward is y and right is x; D3DXMATRIX m; // the rotation matrix D3DXVECTOR3 v; // this is the direction vector wich is given D3DXVECTOR3 r; // resulting direction vector float len = D3DXVec3Length(&v); // length of the initial direction vector // compute matrix D3DXMatrixLookAtLH(&m, &v, &D3DXVECTOR3(0,0,0), &D3DXVECTOR3(0,0,1)); // use the matrix on a vector { 0, len, 0 } D3DXVec3TransformCoord(&r, &D3DXVECTOR3(0,len,0), &m); Now, the vector r should be equal to v, but it isnt. What exactly do I have to do to get the results I need?

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  • Some questions about Vector in STL

    - by skydoor
    I have some questions about vector in STL to clarify..... Where are the objects in vector allocated? heap? does vector have boundary check? If the index out of the boundary, what error will happen? Why array is faster than vector? Is there any case in which vector is not applicable but array is a must?

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  • some qeustions about Vector in STL

    - by skydoor
    I have some questions about vector in STL to clarify..... 1 Where are the objects in vector allocated? heap? 2 does vector have boundary check? If the index out of the boundary, what error will happen? 3 Why array is faster than vector? 4 Is there any case in which vector is not applicable but array is a must?

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  • Finding character in String in Vector.

    - by SoulBeaver
    Judging from the title, I kinda did my program in a fairly complicated way. BUT! I might as well ask anyway xD This is a simple program I did in response to question 3-3 of Accelerated C++, which is an awesome book in my opinion. I created a vector: vector<string> countEm; That accepts all valid strings. Therefore, I have a vector that contains elements of strings. Next, I created a function int toLowerWords( vector<string> &vec ) { for( int loop = 0; loop < vec.size(); loop++ ) transform( vec[loop].begin(), vec[loop].end(), vec[loop].begin(), ::tolower ); that splits the input into all lowercase characters for easier counting. So far, so good. I created a third and final function to actually count the words, and that's where I'm stuck. int counter( vector<string> &vec ) { for( int loop = 0; loop < vec.size(); loop++ ) for( int secLoop = 0; secLoop < vec[loop].size(); secLoop++ ) { if( vec[loop][secLoop] == ' ' ) That just looks ridiculous. Using a two-dimensional array to call on the characters of the vector until I find a space. Ridiculous. I don't believe that this is an elegant or even viable solution. If it was a viable solution, I would then backtrack from the space and copy all characters I've found in a separate vector and count those. My question then is. How can I dissect a vector of strings into separate words so that I can actually count them? I thought about using strchr, but it didn't give me any epiphanies.

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  • C++ STL Map vs Vector speed

    - by sub
    In the interpreter for my experimental programming language I have a symbol table. Each symbol consists of a name and a value (the value can be e.g.: of type string, int, function, etc.). At first I represented the table with a vector and iterated through the symbols checking if the given symbol name fitted. Then I though using a map, in my case map<string,symbol>, would be better than iterating through the vector all the time but: It's a bit hard to explain this part but I'll try. If a variable is retrieved the first time in a program in my language, of course its position in the symbol table has to be found (using vector now). If I would iterate through the vector every time the line gets executed (think of a loop), it would be terribly slow (as it currently is, nearly as slow as microsoft's batch). So I could use a map to retrieve the variable: SymbolTable[ myVar.Name ] But think of the following: If the variable, still using vector, is found the first time, I can store its exact integer position in the vector with it. That means: The next time it is needed, my interpreter knows that it has been "cached" and doesn't search the symbol table for it but does something like SymbolTable.at( myVar.CachedPosition ). Now my (rather hard?) question: Should I use a vector for the symbol table together with caching the position of the variable in the vector? Should I rather use a map? Why? How fast is the [] operator? Should I use something completely different?

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  • C++ std::vector problems

    - by Faur Ioan-Aurel
    For 2 days i tried to explain myself some of the things that are happening in my c++ code,and i can't get a good explanation.I must say that i'm more a java programmer.Long time i used quite a bit the C language but i guess Java erased those skills and now i'm hitting a wall trying to port a few classes from java to c++. So let's say that we have this 2 classes: class ForwardNetwork { protected: ForwardLayer* inputLayer; ForwardLayer* outputLayer; vector<ForwardLayer* > layers; public: void ForwardNetwork::getLayers(std::vector< ForwardLayer* >& result ) { for(int i= 0 ;i< layers.size(); i++){ ForwardLayer* lay = dynamic_cast<ForwardLayer*>(this->layers.at(i)); if(lay != NULL) result.push_back(lay); else cout << "Layer at#" << i << " is null" << endl; } } void ForwardNetwork::addLayer ( ForwardLayer* layer ) { if(layer != NULL) cout << "Before push layer is not null" << endl; //setup the forward and back pointer if ( this->outputLayer != NULL ) { layer->setPrevious ( this->outputLayer ); this->outputLayer->setNext ( layer ); } //update the input layer and outputLayer variables if ( this->layers.size() == 0 ) this->inputLayer = this->outputLayer = layer; else this->outputLayer = layer; //push layer in vector this->layers.push_back ( layer ); for(int i = 0; i< layers.size();i++) if(layers[i] != NULL) cout << "Check::Layer[" << i << "] is not null!" << endl; } }; Second class: class Backpropagation : public Train { public: Backpropagation::Backpropagation ( FeedForwardNetwork* network ){ this->network = network; vector<FeedforwardLayer*> vec; network->getLayers(vec); } }; Now if i add from main() some layers into network via addLayer(..) method it's all good.My vector is just as it should.But after i call Backpropagation() constructor with a network object ,when i enter getLayers(), some of my objects from vector have their address set to NULL(they are randomly chosen:for example if i run my app once with 3 layer's into vector ,the first object from vector is null.If i run it second time first 2 objects are null,third time just first object null and so on). Now i can't explain why this is happening.I must say that all the objects that should be in vector they also live inside the network and they are not NULL; This happens everywhere after i done with addLayer() so not just in the getLayers(). I cant get a good grasp to this problem.I thought first that i might modify my vector.But i can't find such thing. Also why if the reference from vector is NULL ,the reference that lives inside ForwardNetwork as a linked list (inputLayer and outputLayer) is not NULL? I must ask for your help.Please ,if you have some advices don't hesitate! PS: as compiler i use g++ part of gcc 4.6.1 under ubuntu 11.10

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  • Weird behaviour with vector::erase and std::remove_if with end range different from vector.end()

    - by Edison Gustavo Muenz
    Hi, I need to remove elements from the middle of a std::vector. So I tried: struct IsEven { bool operator()(int ele) { return ele % 2 == 0; } }; int elements[] = {1, 2, 3, 4, 5, 6}; std::vector<int> ints(elements, elements+6); std::vector<int>::iterator it = std::remove_if(ints.begin() + 2, ints.begin() + 4, IsEven()); ints.erase(it, ints.end()); After this I would expect that the ints vector have: [1, 2, 3, 5, 6]. In the debugger of Visual studio 2008, after the std::remove_if line, the elements of ints are modified, I'm guessing I'm into some sort of undefined behaviour here. So, how do I remove elements from a Range of a vector?

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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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  • 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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