| Defined in header <algorithm> | ||
|---|---|---|
template< class ForwardIt, class UnaryPredicate > ForwardIt partition_point( ForwardIt first, ForwardIt last, UnaryPredicate p ); | (1) | (since C++11) |
Examines the partitioned (as if by std::partition) range [first, last) and locates the end of the first partition, that is, the first element that does not satisfy p or last if all elements satisfy p.
Parameters
| first, last | - | the partitioned range of elements to examine |
| p | - | unary predicate which returns true for the elements found in the beginning of the range. The signature of the predicate function should be equivalent to the following:
The signature does not need to have |
| Type requirements | ||
- ForwardIt must meet the requirements of ForwardIterator. | ||
- UnaryPredicate must meet the requirements of Predicate. | ||
Return value
The iterator past the end of the first partition within [first, last) or last if all elements satisfy p.
Complexity
The number of applications of the predicate p is logarithmic in the distance between first and last.
Example
#include <algorithm>
#include <array>
#include <iostream>
#include <iterator>
int main()
{
std::array<int, 9> v = { 1, 2, 3, 4, 5, 6, 7, 8, 9 };
auto is_even = [](int i){ return i % 2 == 0; };
std::partition(v.begin(), v.end(), is_even);
auto p = std::partition_point(v.begin(), v.end(), is_even);
std::cout << "Before partition:\n ";
std::copy(v.begin(), p, std::ostream_iterator<int>(std::cout, " "));
std::cout << "\nAfter partition:\n ";
std::copy(p, v.end(), std::ostream_iterator<int>(std::cout, " "));
}Output:
Before partition:
8 2 6 4
After partition:
5 3 7 1 9See also
| (C++11) | checks whether a range is sorted into ascending order (function template) |
Please login to continue.