std::min_element() algorithm
- since C++17
- until C++17
template< class ForwardIt >
ForwardIt min_element( ForwardIt first, ForwardIt last );
// (2)
template< class ForwardIt, class Compare >
ForwardIt min_element( ForwardIt first, ForwardIt last, Compare comp );
// (3)
template< class ExecutionPolicy, class ForwardIt >
ForwardIt min_element( ExecutionPolicy&& policy,
ForwardIt first, ForwardIt last );
// (4)
template< class ExecutionPolicy, class ForwardIt, class Compare >
ForwardIt min_element( ExecutionPolicy&& policy,
ForwardIt first, ForwardIt last, Compare comp );
template< class ForwardIt >
ForwardIt min_element( ForwardIt first, ForwardIt last );
// (2)
template< class ForwardIt, class Compare >
ForwardIt min_element( ForwardIt first, ForwardIt last, Compare comp );
Finds the smallest element in the range [first
; last
).
-
(1) Elements are compared using
operator<
. -
(2) Elements are compared using the given binary comparison function
comp
.
Parameters
first last | The range to find the smallest element in. |
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). The signature of the comparison function should be equivalent to the following:
|
Type requirements
RandomIt | LegacyRandomAccessIterator |
Return value
Iterator to the greatest element in the range [first
; last
).
If several elements in the range are equivalent to the greatest element, returns the iterator to the first such element.
Returns last
if the range is empty.
Complexity
Given N
as std::distance(first, last)
:
Exactly min(N - 1, 0)
comparisons.
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(2)
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;
}
Examples
#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";
}
min element has value -4 and index [2]
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