std::max_element
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在头文件 <algorithm> 中定义
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template< class ForwardIt > ForwardIt max_element( ForwardIt first, ForwardIt last ); |
(1) | |
template< class ForwardIt, class Compare > ForwardIt max_element( ForwardIt first, ForwardIt last, Compare comp ); |
(2) | |
Finds the greatest element in the range [first, last)
. The first version uses operator< to compare the values, the second version uses the given comparison function comp
.
目录 |
[编辑] 参数
first, last | - | 前向迭代器定义的范围检查
原文: forward iterators defining the range to examine |
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. |
类型要求 | ||
-ForwardIt 必须满足 ForwardIterator 的要求。
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[编辑] 返回值
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.
[编辑] 复杂度
[编辑] 可能的实现
版本一 |
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template<class ForwardIt> ForwardIt max_element(ForwardIt first, ForwardIt last) { if (first == last) { return last; } ForwardIt largest = first; ++first; for (; first != last; ++first) { if (*largest < *first) { largest = first; } } return largest; } |
版本二 |
template<class ForwardIt, class Compare> ForwardIt max_element(ForwardIt first, ForwardIt last, Compare comp) { if (first == last) { return last; } ForwardIt largest = first; ++first; for (; first != last; ++first) { if (comp(*largest, *first)) { largest = first; } } return largest; } |
[编辑] 示例
#include <algorithm> #include <iostream> #include <vector> #include <cmath> static bool abs_compare(int a, int b) { return (std::abs(a) < std::abs(b)); } int main() { std::vector<int> v{ 3, 1, -14, 1, 5, 9 }; std::vector<int>::iterator result; result = std::max_element(v.begin(), v.end()); std::cout << "max element at: " << std::distance(v.begin(), result) << '\n'; result = std::max_element(v.begin(), v.end(), abs_compare); std::cout << "max element (absolute) at: " << std::distance(v.begin(), result); }
输出:
max element at: 5 max element (absolute) at: 2
[编辑] 另请参阅
返回区间内的最小元素 (函数模板) | |
(C++11) |
返回区间内的最小元素和最大元素 (函数模板) |
返回两个元素中的较大者 (函数模板) |