thrust::upper_bound

Defined in thrust/binary_search.h

template<class ForwardIterator, class LessThanComparable> ForwardIterator thrust::upper_bound(ForwardIterator first, ForwardIterator last, const LessThanComparable &value)

upper_bound is a version of binary search: it attempts to find the element value in an ordered range [first, last). Specifically, it returns the last position where value could be inserted without violating the ordering. This version of upper_bound uses operator< for comparison and returns the furthermost iterator i in [first, last) such that, for every iterator j in [first, i), value < *j is false.

The following code snippet demonstrates how to use upper_bound to search for values in a ordered range.

#include <thrust/binary_search.h>
#include <thrust/device_vector.h>
...
thrust::device_vector<int> input(5);

input[0] = 0;
input[1] = 2;
input[2] = 5;
input[3] = 7;
input[4] = 8;

thrust::upper_bound(input.begin(), input.end(), 0); // returns input.begin() + 1
thrust::upper_bound(input.begin(), input.end(), 1); // returns input.begin() + 1
thrust::upper_bound(input.begin(), input.end(), 2); // returns input.begin() + 2
thrust::upper_bound(input.begin(), input.end(), 3); // returns input.begin() + 2
thrust::upper_bound(input.begin(), input.end(), 8); // returns input.end()
thrust::upper_bound(input.begin(), input.end(), 9); // returns input.end()

See also

lower_bound

See also

equal_range

See also

Binary Search

Parameters

first – The beginning of the ordered sequence.
last – The end of the ordered sequence.
value – The value to be searched.

Template Parameters

ForwardIterator – is a model of Forward Iterator.
LessThanComparable – is a model of LessThanComparable.

Returns

The furthermost iterator i, such that value < *i is false.