For the first version:
• BidirectionalIterator is a model of Bidirectional Iterator.
• BidirectionalIterator is mutable.
• BidirectionalIterator's value type is a model of LessThan Comparable.
• The ordering on objects of BidirectionalIterator's value type is a strict weak ordering, as defined in the LessThan Comparable requirements.
For the second version: • BidirectionalIterator is a model of Bidirectional Iterator.
• BidirectionalIterator is mutable.
• StrictWeakOrdering is a model of Strict Weak Ordering.
• BidirectionalIterator's value type is convertible to StrictWeakOrdering's argument type.
Preconditions For the first version:
• [first, middle) is a valid range.
• [middle, last) is a valid range.
• [first, middle) is in ascending order. That is, for every pair of iterators i and j in [first, middle) such that i precedes j, *j < *i is false.
• [middle, last) is in ascending order. That is, for every pair of iterators i and j in [middle, last) such that i precedes j, *j < *i is false.
For the second version:
• [first, middle) is a valid range.
• [middle, last) is a valid range.
• [first, middle) is in ascending order. That is, for every pair of iterators i and j in [first, middle) such that i precedes j, comp(*j, *i) is false.
• [middle, last) is in ascending order. That is, for every pair of iterators i and j in [middle, last) such that i precedes j, comp(*j, *i) is false.
Complexity Inplace_merge is an adaptive algorithm: it attempts to allocate a temporary memory buffer, and its run-time complexity depends on how much memory is available. Inplace_merge performs no comparisons if [first, last) is an empty range. Otherwise, worst-case behavior (if no auxiliary memory is available) is O(N log(N)) , where N is last – first , and best case (if a large enough auxiliary memory buffer is available) is at most (last – first) – 1 comparisons.
Example int main() {
int A[] = { 1, 3, 5, 7, 2, 4, 6, 8 };
inplace_merge(A, A + 4, A + 8);
copy(A, A + 8, ostream_iterator<int>(cout, ' '));
// The output is '1 2 3 4 5 6 7 8'.
}
Notes [1] Note that you may use an ordering that is a strict weak ordering but not a total ordering; that is, there might be values x and y such that x < y, x > y, and x == y are all false. (See the LessThan Comparable requirements for a fuller discussion.) Two elements x and y are equivalent if neither x < y nor y < x. If you're using a total ordering, however (if you're using strcmp, for example, or if you're using ordinary arithmetic comparison on integers), then you can ignore this technical distinction: for a total ordering, equality and equivalence are the same.
See also merge, set_union, sort
Set operations on sorted ranges
Category: algorithms
Component type: function
Prototype Includes is an overloaded name; there are actually two includes functions.
template <class InputIterator1, class InputIterator2>
bool includes(InputIterator1 first1, InputIterator1 last1, InputIterator2 first2, InputIterator2 last2);
template <class InputIterator1, class InputIterator2, class StrictWeakOrdering>
bool includes(InputIterator1 first1, InputIterator1 last1, InputIterator2 first2, InputIterator2 last2, StrictWeakOrdering comp);
Description Includes tests whether one sorted range includes another sorted range. That is, it returns true if and only if, for every element in [first2, last2), an equivalent element [1] is also present in [first1, last1) [2]. Both [first1, last1) and [first2, last2) must be sorted in ascending order.
The two versions of includes differ in how they define whether one element is less than another. The first version compares objects using operator<, and the second compares objects using the function object comp.
Definition Defined in the standard header algorithm, and in the nonstandard backward-compatibility header algo.h.
Requirements on types For the first version:
• InputIterator1 is a model of Input Iterator.
• InputIterator2 is a model of Input Iterator.
• InputIterator1 and InputIterator2 have the same value type.
• InputIterator's value type is a model of LessThan Comparable.
