std::min_element

 

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Defined in header <algorithm>
template< class ForwardIt > ForwardIt min_element( ForwardIt first, ForwardIt last );	(1)
template< class ForwardIt, class Compare > ForwardIt min_element( ForwardIt first, ForwardIt last, Compare comp );	(2)

查找的範圍內[first, last)中最小的元素。使用operator<的值進行比較的第一個版本，第二個版本使用給定的比較函數comp.

Original:

Finds the smallest element in the range [first, last). The first version uses operator< to compare the values, the second version uses the given comparison function comp.

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參數

first, last	-	前向迭代器定義的範圍檢查 Original: forward iterators defining the range to examine The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
cmp	-	comparison function which returns ​true if 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); The signature does not need to have const &, but the function must not modify the objects passed to it. The types Type1 and Type2 must be such that an object of type ForwardIt can be dereferenced and then implicitly converted to both of them. ​
Type requirements
- ForwardIt must meet the requirements of ForwardIterator.

返回值

迭代器的範圍內[first, last)最小的元素。如果幾個元素的取值範圍為最小的元素是等價的，返回的迭代器的第一個這樣的元件。返回last的範圍內是空

Original:

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.

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複雜性

究竟max(N-1,0)比較，N = std::distance(first, last).

Original:

Exactly max(N-1,0) comparisons, where N = std::distance(first, last).

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可能的實現

First version
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; }
Second version
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; }

為例

#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 at: " << std::distance(v.begin(), result);
}

Output:

min element at: 1

另請參閱

max_element	返回區間內的最大元素 （函數模板）
minmax_element （C++11）	返回區間內的最小元素和最大元素 （函數模板）
min	返回兩個元素中的較小者 （函數模板）