Standard C++ Library Reference ISO/IEC (VERSION3)

otherwise be copied to adjacent elements, the function copies only the element from the ordered

range [first1, last1) and skips the other. An element from one sequence that has

equivalent ordering with no element from the other sequence is copied from the ordered range

[first1, last1) and skipped from the other. Thus, the function merges two ordered

sequences to form another ordered sequence that is effectively the difference of two sets.

If dest and first1 designate regions of storage, the range [dest, dest + K) must not

overlap the range [first1, last1). If dest and first2 designate regions of storage, the

range [dest, dest + K) must not overlap the range [first2, last2). The function

evaluates the ordering predicate X < Y at most 2 * ((last1 - first1) + (last2 -

first2)) - 1 times.

The second template function behaves the same, except that it replaces operator<(X, Y)

with pred(X, Y).

set_intersection

template<class InIt1, class InIt2, class OutIt>

OutIt set_intersection(InIt1 first1, InIt1 last1,

InIt2 first2, InIt2 last2, OutIt dest);

template<class InIt1, class InIt2, class OutIt,

class Pr>

OutIt set_intersection(InIt1 first1, InIt1 last1,

InIt2 first2, InIt2 last2, OutIt dest, Pr pred);

The first template function alternately copies values from two sequences designated by iterators

in the ranges [first1, last1) and [first2, last2), both ordered by operator<,

to form a merged sequence of length K beginning at dest, also ordered by operator<. The

function then returns dest + K.

The merge occurs without altering the relative order of elements within either sequence.

Moreover, for two elements from different sequences that have equivalent ordering that would