std::upper_bound

Parameters

first, last

Forward iterators to the initial and final positions of a sorted (or properly partitioned) sequence. The range used is [first,last), which contains all the elements between first and last, including the element pointed by first but not the element pointed by last.

val

Value of the upper bound to search for in the range.
For (1), T shall be a type supporting being compared with elements of the range [first,last) as the left-hand side operand of operator<.

comp

Binary function that accepts two arguments (the first is always val, and the second of the type pointed by ForwardIterator), and returns a value convertible to bool. The value returned indicates whether the first argument is considered to go before the second.
The function shall not modify any of its arguments.
This can either be a function pointer or a function object.

Return value

Example

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// lower_bound/upper_bound example
#include <iostream>     // std::cout
#include <algorithm>    // std::lower_bound, std::upper_bound, std::sort
#include <vector>       // std::vector
int main () {
  int myints[] = {10,20,30,30,20,10,10,20};
  std::vector<int> v(myints,myints+8);           // 10 20 30 30 20 10 10 20
  std::sort (v.begin(), v.end());                // 10 10 10 20 20 20 30 30
  std::vector<int>::iterator low,up;
  low=std::lower_bound (v.begin(), v.end(), 20); //          ^
  up= std::upper_bound (v.begin(), v.end(), 20); //                   ^
  std::cout << "lower_bound at position " << (low- v.begin()) << '\n';
  std::cout << "upper_bound at position " << (up - v.begin()) << '\n';
  return 0;
}

lower_bound at position 3
upper_bound at position 6

Complexity

Data races

Exceptions

See also

lower_bound

Return iterator to lower bound (function template)

equal_range

Get subrange of equal elements (function template)

binary_search

Test if value exists in sorted sequence (function template)

max_element

Return largest element in range (function template)