You can get a pointer to the first element as follows: int* pv = &v[0]; This pointer is only valid as long as the vector is not reallocated. Reallocation happens automatically if you insert more elements than will fit in the vector’s remaining capacity (that is, if v.size() + NumberOfNewElements > v.capacity(). You can use … Read more
You use a move_iterator with insert: v1.insert(v1.end(), make_move_iterator(v2.begin()), make_move_iterator(v2.end())); The example in 24.5.3 is almost exactly this. You’ll get the optimization you want if (a) vector::insert uses iterator-tag dispatch to detect the random-access iterator and precalculate the size (which you’ve assumed it does in your example that copies), and (b) move_iterator preserves the iterator category … Read more
Your code (vector1 == vector2) is correct C++ syntax. There is an == operator for vectors. If you want to compare short vector with a portion of a longer vector, you can use theequal() operator for vectors. (documentation here) Here’s an example: using namespace std; if( equal(vector1.begin(), vector1.end(), vector2.begin()) ) DoSomething();
Standard says (draft N3690; this is post C++11, pre C++14): [res.on.functions] 1 In certain cases (replacement functions, handler functions, operations on types used to instantiate standard library template components), the C++standard library depends on components supplied by a C++program. If these components do not meet their requirements, the Standard places no requirements on the implementation. … Read more
No. The elements of a vector are stored in a dynamically allocated block of memory; otherwise, the capacity of the vector could not increase. The vector object just holds a pointer to that block. The requirement that the elements be stored sequentially applies only to the elements themselves, and not to any dynamically allocated members … Read more
I found another forum post, where somebody seems to have reported the same exact problem that you are having. Please check to see if you have _DEBUG defined either in your project settings (under C/C++ — Preprocessor) or somewhere in your code (or include files). It looks as if std::vector thinks you are building a … Read more
If there are different indexes for vertex coordinates and texture coordinates, then the vertex positions must be “duplicated”. The vertex coordinate and its attributes (like texture coordinate) form a tuple. Each vertex coordinate must have its own texture coordinates and attributes. You can think of a 3D vertex coordinate and a 2D texture coordinate as … Read more
In theory, it is called each time, since a for loop: for(initialization; condition; increment) body; is expanded to something like { initialization; while(condition) { body; increment; } } (notice the curly braces, because initialization is already in an inner scope) In practice, if the compiler understands that a piece of your condition is invariant through … Read more
Yes, std::vector<T>::push_back() creates a copy of the argument and stores it in the vector. If you want to store pointers to objects in your vector, create a std::vector<whatever*> instead of std::vector<whatever>. However, you need to make sure that the objects referenced by the pointers remain valid while the vector holds a reference to them (smart … Read more
23.2.1 / p10 / b6: Unless otherwise specified … no swap() function invalidates any references, pointers, or iterators referring to the elements of the containers being swapped. … Nowhere does it “specify otherwise” for vector. So this outlaws the SBO for vector. string is not bound by this rule because it does “specify otherwise” in … Read more