upper_bound (3C++std) - Tru64 UNIX
Standard C++ LibraryCopyright 1996, Rogue Wave Software, Inc.
NAME
upper_bound - Determines the last valid position for a value in a sorted
container.
SYNOPSIS
#include <algorithm>
template <class ForwardIterator, class T>
ForwardIterator
upper_bound(ForwardIterator first, ForwardIterator last,
const T& value);
template <class ForwardIterator, class T, class Compare>
ForwardIterator
upper_bound(ForwardIterator first, ForwardIterator last,
const T& value, Compare comp);
DESCRIPTION
The upper_bound algorithm is part of a set of binary search algorithms.
All of these algorithms perform binary searches on ordered containers.
Each algorithm has two versions. The first version uses the less than
operator (operator<) to perform the comparison, and assumes that the
sequence has been sorted using that operator. The second version allows
you to include a function object of type Compare, and assumes that Compare
is the function used to sort the sequence. The function object must be a
binary predicate.
The upper_bound algorithm finds the last position in a container that
value can occupy without violating the container's ordering. upper_bound's
return value is the iterator for the first element in the container that is
greater than value, or, when the comparison operator is used, the first
element that does not satisfy the comparison function. Because the
algorithm is restricted to using the less than operator or the user-defined
function to perform the search, upper_bound returns an iterator i in the
range [first, last) such that for any iterator j in the range [first, i)
the appropriate version of the following conditions holds:
!(value < *j)
or
comp(value, *j) == false
COMPLEXITY
upper_bound performs at most log(last - first) + 1 comparisons.
EXAMPLE
//
// ul_bound.cpp
//
#include <vector>
#include <algorithm>
#include <iostream.h>
int main()
{
typedef vector<int>::iterator iterator;
int d1[11] = {0,1,2,2,3,4,5,5,5,6,7};
// Set up a vector
vector<int> v1(d1,d1 + 11);
// Try lower_bound variants
iterator it1 = lower_bound(v1.begin(),v1.end(),3);
// it1 = v1.begin() + 4
iterator it2 =
lower_bound(v1.begin(),v1.end(),2,less<int>());
// it2 = v1.begin() + 4
// Try upper_bound variants
iterator it3 = upper_bound(v1.begin(),v1.end(),3);
// it3 = vector + 5
iterator it4 =
upper_bound(v1.begin(),v1.end(),2,less<int>());
// it4 = v1.begin() + 5
cout << endl << endl
<< "The upper and lower bounds of 3: ( "
<< *it1 << " , " << *it3 << " ]" << endl;
cout << endl << endl
<< "The upper and lower bounds of 2: ( "
<< *it2 << " , " << *it4 << " ]" << endl;
return 0;
}
Output :
The upper and lower bounds of 3: ( 3 , 4 ]
The upper and lower bounds of 2: ( 2 , 3 ]
WARNING
If your compiler does not support default template parameters, then you
need to always supply the Allocator template argument. For instance, you
will need to write :
vector<int, allocator<int> >
instead of :
vector<int>
SEE ALSO
lower_bound, equal_range
STANDARDS CONFORMANCE
ANSI X3J16/ISO WG21 Joint C++ Committee
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