The following is a list of algorithms that can be used for finding elements in a range:
- Use std::find() to find a value in a range; this algorithm returns an iterator to the first element equal to the value:
std::vector<int> v{ 1, 1, 2, 3, 5, 8, 13 };
auto it = std::find(v.cbegin(), v.cend(), 3);
if (it != v.cend()) std::cout << *it << std::endl;
- Use std::find_if() to find a value in a range that meets a criterion from a unary predicate; this algorithm returns an iterator to the first element for which the predicate returns true:
std::vector<int> v{ 1, 1, 2, 3, 5, 8, 13 };
auto it = std::find_if(v.cbegin(), v.cend(),
[](int const n) {return n > 10; });
if (it != v.cend()) std::cout << *it << std::endl;
- Use std::find_if_not() to find a value in a range that does not meet a criterion from a unary predicate; this algorithm returns an iterator to the first element for which the predicate returns false:
std::vector<int> v{ 1, 1, 2, 3, 5, 8, 13 };
auto it = std::find_if_not(v.cbegin(), v.cend(),
[](int const n) {return n % 2 == 1; });
if (it != v.cend()) std::cout << *it << std::endl;
- Use std::find_first_of() to search for the occurrence of any value from a range in another range; this algorithm returns an iterator to the first element that is found:
std::vector<int> v{ 1, 1, 2, 3, 5, 8, 13 };
std::vector<int> p{ 5, 7, 11 };
auto it = std::find_first_of(v.cbegin(), v.cend(),
p.cbegin(), p.cend());
if (it != v.cend())
std::cout << "found " << *it
<< " at index " << std::distance(v.cbegin(), it)
<< std::endl;
- Use std::find_end() to find the last occurrence of a subrange of elements in a range; this algorithm returns an iterator to the first element of the last subrange in the range:
std::vector<int> v1{ 1, 1, 0, 0, 1, 0, 1, 0, 1, 0, 1, 1 };
std::vector<int> v2{ 1, 0, 1 };
auto it = std::find_end(v1.cbegin(), v1.cend(),
v2.cbegin(), v2.cend());
if (it != v1.cend())
std::cout << "found at index "
<< std::distance(v1.cbegin(), it) << std::endl;
- Use std::search() to search for the first occurrence of a subrange in a range; this algorithm returns an iterator to the first element of the subrange in the range:
auto text = "The quick brown fox jumps over the lazy dog"s;
auto word = "over"s;
auto it = std::search(text.cbegin(), text.cend(),
word.cbegin(), word.cend());
if (it != text.cend())
std::cout << "found " << word
<< " at index "
<< std::distance(text.cbegin(), it) << std::endl;
- Use std::search() with a searcher, which is a class that implements a searching algorithm and meets some predefined criteria. This overload of std::search() was introduced in C++17, and available standard searchers implement the Boyer-Moore and the Boyer-Moore-Horspool string searching algorithms:
auto text = "The quick brown fox jumps over the lazy dog"s;
auto word = "over"s;
auto it = std::search(
text.cbegin(), text.cend(),
std::make_boyer_moore_searcher(word.cbegin(), word.cend()));
if (it != text.cend())
std::cout << "found " << word
<< " at index "
<< std::distance(text.cbegin(), it) << std::endl;
- Use std::search_n() to search for N consecutive occurrences of a value in a range; this algorithm returns an iterator to the first element of the found sequence in the range:
std::vector<int> v{ 1, 1, 0, 0, 1, 0, 1, 0, 1, 0, 1, 1 };
auto it = std::search_n(v.cbegin(), v.cend(), 2, 0);
if (it != v.cend())
std::cout << "found at index "
<< std::distance(v.cbegin(), it) << std::endl;
- Use std::adjacent_find() to find two adjacent elements in a range that are equal or satisfy a binary predicate; this algorithm returns an iterator to the first element that is found:
std::vector<int> v{ 1, 1, 2, 3, 5, 8, 13 };
auto it = std::adjacent_find(v.cbegin(), v.cend());
if (it != v.cend())
std::cout << "found at index "
<< std::distance(v.cbegin(), it) << std::endl;
auto it = std::adjacent_find(
v.cbegin(), v.cend(),
[](int const a, int const b) {
return IsPrime(a) && IsPrime(b); });
if (it != v.cend())
std::cout << "found at index "
<< std::distance(v.cbegin(), it) << std::endl;
- Use std::binary_search() to find whether an element exists in a sorted range; this algorithm returns a Boolean value to indicate whether the value was found or not:
std::vector<int> v{ 1, 1, 2, 3, 5, 8, 13 };
auto success = std::binary_search(v.cbegin(), v.cend(), 8);
if (success) std::cout << "found" << std::endl;
- Use std::lower_bound() to find the first element in a range not less than a specified value; this algorithm returns an iterator to the element:
std::vector<int> v{ 1, 1, 2, 3, 5, 8, 13 };
auto it = std::lower_bound(v.cbegin(), v.cend(), 1);
if (it != v.cend())
std::cout << "lower bound at "
<< std::distance(v.cbegin(), it) << std::endl;
- Use std::upper_bound() to find the first element in a range greater than a specified value; this algorithm returns an iterator to the element:
std::vector<int> v{ 1, 1, 2, 3, 5, 8, 13 };
auto it = std::upper_bound(v.cbegin(), v.cend(), 1);
if (it != v.cend())
std::cout << "upper bound at "
<< std::distance(v.cbegin(), it) << std::endl;
- Use std::equal_range() to find a subrange in a range whose values are equal to a specified value. This algorithm returns a pair of iterators defining the first and the one-past-end iterators to the subrange; these two iterators are equivalent to those returned by std::lower_bound() and std::upper_bound():
std::vector<int> v{ 1, 1, 2, 3, 5, 8, 13 };
auto bounds = std::equal_range(v.cbegin(), v.cend(), 1);
std::cout << "range between indexes "
<< std::distance(v.cbegin(), bounds.first)
<< " and "
<< std::distance(v.cbegin(), bounds.second)
<< std::endl;