All of the answers so far have copied a vector to a set. Since you asked to 'convert' a vector to a set, I'll show a more optimized method which moves each element into a set instead of copying each element: std::vector<T> v = /*...*/; std::set<T> s(std::make_move_iterator(v.begin()), std::make_move_iterator(v.end()));

2011年12月31日 · Of course you could maintain a vector of unique items, but your performance would suffer a lot when you do set-oriented operations. For example, assume that you have a set of 10000 items and a vector of 10000 distinct unordered items. Now suppose that you need to check if a value X is among the values in the set (or among the values in the vector).

2012年7月5日 · How to do the vector of sets in C++? I want to have a set for the different levels that are in my code. A set at each level will be holding integer values. The number of these sets should be dynamic depending on the number of levels required ( which is given as input ). For this, I wanted to have a dynamic set structure. How can I achieve this?

2011年4月8日 · If vector < set< char >> v is exactly what you've got there (I hope you cut and pasted), you've run into one of the annoying little features of C++. Those >> look to you like two closing angle brackets for two templates. They look like a right shift operator to the compiler. Change them to > > with a space in between.

2014年6月30日 · You're close. You need to pull the vector out of the set iterator. See below. main() { std::set< std::vector<int> > conjunto; std::vector<int> v0 = std::vector<int>(3 ...

2019年8月27日 · I am trying to create a set of vectors in C++. I want the vectors [1,2] and [2,1] to be considered equal in the set. So both should not exist in the set. Also a vector can have the same element mul...

2009年7月17日 · I have a vector of booleans. I need to set its elements from n-th to m-th to true. Is there an elegant way to do this without using a loop? Edit: Tanks to all those who pointed out the problems with using vector<bool>. However, I was looking for a more general solution, like the one given by jalf.

So, I created a vector: std::vector<int> vec = {10, 20, 30, 40, 50}; and I ran std::cout << vec[5]; multiple times in my gcc and every time, it displayed 0. On the other hand, when I tried running std::cout << vec.at(5); , I got terminate called after throwing an instance of 'std::out_of_range' what(): vector::_M_range_check: __n (which is 5 ...

In particular, this allows vector to only do one allocation (since it can't determine the distance of set iterators in O(1)), and, if it wasn't defined for vector to zero out each element when constructed, this could be worthwhile to allow the copy to boil down to a memcpy.

2009年11月3日 · If your vector contains POD types, it is safe to use memset on it - the storage of a vector is guaranteed to be contiguous. memset(&vec[0], 0, sizeof(vec[0]) * vec.size()); Edit: Sorry to throw an undefined term at you - POD stands for Plain Old Data, i.e. the types that were available in C and the structures built from them.