|Category: algorithms||Component type: function|
template <class ForwardIterator, class Generator> void generate(ForwardIterator first, ForwardIterator last, Generator gen);
vector<int> V; ... generate(V.begin(), V.end(), rand);
 The function object gen is invoked for each iterator in the range [first, last), as opposed to just being invoked a single time outside the loop. This distinction is important because a Generator need not return the same result each time it is invoked; it is permitted to read from a file, refer to and modify local state, and so on.
 The reason that generate requires its argument to be a mutable Forward Iterator, rather than just an Output Iterator, is that it uses a range [first, last) of iterators. There is no sensible way to describe a range of Output Iterators, because it is impossible to compare two Output Iterators for equality. The generate_n algorithm does have an interface that permits use of an Output Iterator.