std::min_element
Defined in header <algorithm>
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(1) | ||
template< class ForwardIt > ForwardIt min_element( ForwardIt first, ForwardIt last ); |
(until C++17) | |
template< class ForwardIt > constexpr ForwardIt min_element( ForwardIt first, ForwardIt last ); |
(since C++17) | |
template< class ExecutionPolicy, class ForwardIt > ForwardIt min_element( ExecutionPolicy&& policy, |
(2) | (since C++17) |
(3) | ||
template< class ForwardIt, class Compare > ForwardIt min_element( ForwardIt first, ForwardIt last, Compare comp ); |
(until C++17) | |
template< class ForwardIt, class Compare > constexpr ForwardIt min_element( ForwardIt first, ForwardIt last, |
(since C++17) | |
template< class ExecutionPolicy, class ForwardIt, class Compare > ForwardIt min_element( ExecutionPolicy&& policy, |
(4) | (since C++17) |
Finds the smallest element in the range [
first,
last)
.
operator<
.
std::is_execution_policy_v<std::decay_t<ExecutionPolicy>> is true. |
(until C++20) |
std::is_execution_policy_v<std::remove_cvref_t<ExecutionPolicy>> is true. |
(since C++20) |
Parameters
first, last | - | forward iterators defining the range to examine |
policy | - | the execution policy to use. See execution policy for details. |
comp | - | comparison function object (i.e. an object that satisfies the requirements of Compare) which returns true if a is less than b .The signature of the comparison function should be equivalent to the following: bool cmp(const Type1& a, const Type2& b); While the signature does not need to have const&, the function must not modify the objects passed to it and must be able to accept all values of type (possibly const) |
Type requirements | ||
-ForwardIt must meet the requirements of LegacyForwardIterator.
|
Return value
Iterator to the smallest element in the range [
first,
last)
. If several elements in the range are equivalent to the smallest element, returns the iterator to the first such element. Returns last if the range is empty.
Complexity
Exactly max(N-1,0) comparisons, where N = std::distance(first, last).
Exceptions
The overloads with a template parameter named ExecutionPolicy
report errors as follows:
- If execution of a function invoked as part of the algorithm throws an exception and
ExecutionPolicy
is one of the standard policies, std::terminate is called. For any otherExecutionPolicy
, the behavior is implementation-defined. - If the algorithm fails to allocate memory, std::bad_alloc is thrown.
Possible implementation
min_element (1) |
---|
template<class ForwardIt> ForwardIt min_element(ForwardIt first, ForwardIt last) { if (first == last) return last; ForwardIt smallest = first; ++first; for (; first != last; ++first) if (*first < *smallest) smallest = first; return smallest; } |
min_element (3) |
template<class ForwardIt, class Compare> ForwardIt min_element(ForwardIt first, ForwardIt last, Compare comp) { if (first == last) return last; ForwardIt smallest = first; ++first; for (; first != last; ++first) if (comp(*first, *smallest)) smallest = first; return smallest; } |
Example
#include <algorithm> #include <iostream> #include <vector> int main() { std::vector<int> v {3, 1, -4, 1, 5, 9}; std::vector<int>::iterator result = std::min_element(v.begin(), v.end()); std::cout << "min element has value " << *result << " and index [" << std::distance(v.begin(), result) << "]\n"; }
Output:
min element has value -4 and index [2]
Defect reports
The following behavior-changing defect reports were applied retroactively to previously published C++ standards.
DR | Applied to | Behavior as published | Correct behavior |
---|---|---|---|
LWG 212 | C++98 | the return value was not specified if first == last | returns last in this case |
See also
returns the largest element in a range (function template) | |
(C++11) |
returns the smallest and the largest elements in a range (function template) |
returns the smaller of the given values (function template) | |
(C++20) |
returns the smallest element in a range (niebloid) |