I don’t think this would be possible. On some STL libraries you actually have a vector iterator as a pointer type, i.e. std::vector<T>::iterator is a T* so I can’t think of any way you could get back to the container type from that.
int len = hex.length(); std::string newString; for(int i=0; i< len; i+=2) { std::string byte = hex.substr(i,2); char chr = (char) (int)strtol(byte.c_str(), null, 16); newString.push_back(chr); }
A partial order would not be sufficient to implement some algorithms, such as a sorting algorithm. Since a partially ordered set does not necessarily define a relationship between all elements of the set, how would you sort a list of two items that do not have an order relationship within the partial order?
You can use GMan’s answer — but the question is, why do you want to use std::copy? You should use the member function std::map<k, v>::insert instead. m2.insert(m1.begin(), m1.end());
I’ve added a few lines to your code. That’s sufficient to make it clear why this is disallowed: void f(vector<const T*>& p) { static const T ct; p.push_back(&ct); // adds a const T* to nonConstVec ! } int main() { vector<T*> nonConstVec; f(nonConstVec); nonConstVec.back()->nonConstFunction(); }
Element access time in a typical implementation of a std::vector is the same as element access time in an ordinary array available through a pointer object (i.e. a run-time pointer value) std::vector<int> v; int *pa; … v[i]; pa[i]; // Both have the same access time However, the access time to an element of an array … Read more
The problem you’re having is that the compiler doesn’t know which versions of your template to instantiate. When you move the implementation of your function to x.cpp it is in a different translation unit from main.cpp, and main.cpp can’t link to a particular instantiation because it doesn’t exist in that context. This is a well-known … Read more
Although your question is not very clear, I’m going to assume you mean a 2D vector to mean a vector of vectors: vector< vector<int> > vvi; Then you need to use two iterators to traverse it, the first the iterator of the “rows”, the second the iterators of the “columns” in that “row”: //assuming you … Read more
If you want to watch more than one element at the same time, you can append a comma and the number of elements as so: (v._Myfirst)[startIndex], count However, note that count must be a constant, it cannot be the result of another expression.
Unfortunately, this program has undefined behavior. C++11 ยง17.6.4.2.1: A program may add a template specialization for any standard library template to namespace std only if the declaration depends on a user-defined type and the specialization meets the standard library requirements for the original template and is not explicitly prohibited. hash<pair<int,int>> depends on primitive and standard … Read more