C++ algorithm lower_bound() function
Example
Find the lowest value that is at or above "4" in a vector:
vector<int> numbers = {1, 7, 3, 5, 9, 2};
sort(numbers.begin(), numbers.end());
auto it = lower_bound(numbers.begin(), numbers.end(), 4);
if (it != numbers.end()) {
cout << *it << " is the first value at or above 4";
} else {
cout << "No elements found at or above the lower bound";
}
Definition and Usage
The lower_bound() function is an efficient algorithm to find the first value in a sorted data range that is at or above a specified lower bound.
If the data range is not already sorted then the function may return an incorrect result. The sort() function can be used to sort elements in the data range.
The range of data is specified by iterators.
Syntax
lower_bound(iterator start, iterator end, <type> bound);<type> refers to the type of the data that the range contains.
Parameter Values
| Parameter | Description |
|---|---|
| start | Required. An iterator pointing to the start of the data range. |
| end | Required. An iterator pointing to the end of the data range. Elements up to this position will be included, but the element at this position will not be. |
| bound | Required. Specifies the lower bound. |
Technical Details
| Returns: | An iterator pointing to the element containing the first value which is at or above the lower bound. If no element can be found then it returns the end of the data range. |
|---|
Related Pages
Read more about data structures in our Data Structures Tutorial.
Read more about iterators in our Iterators Tutorial.
Read more about algorithms in our Algorithms Tutorial.
