std::lexicographical_compare
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在头文件 <algorithm> 中定义
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template< class InputIt1, class InputIt2 > bool lexicographical_compare( InputIt1 first1, InputIt1 last1, |
(1) | |
template< class InputIt1, class InputIt2, class Compare > bool lexicographical_compare( InputIt1 first1, InputIt1 last1, |
(2) | |
第一范围[first1, last1)检查是否是字典“小于”比第二范围[first2, last2)。 operator<的第一个版本使用比较的元素,第二个版本使用给定的比较函数
comp
.原文:
Checks if the first range [first1, last1) is lexicographically less than the second range [first2, last2). The first version uses operator< to compare the elements, the second version uses the given comparison function
comp
.辞书比较是一个具有以下属性的操作:
原文:
Lexicographical comparison is a operation with the following properties:
- 比较两个范围元素的元素.....原文:Two ranges are compared element by element.
- 第一个不匹配,元素定义的范围是字典“少”或“较大”比其他.原文:The first mismatching element defines which range is lexicographically less or greater than the other.
- 如果一个范围是一个前缀的情况,在较短的范围是字典“小于”比其他.原文:If one range is a prefix of another, the shorter range is lexicographically less than the other.
- 如果两个范围有等同的元件,并具有相同的长度,则范围是字典“等于”.原文:If two ranges have equivalent elements and are of the same length, then the ranges are lexicographically equal.
- 空的范围是字典“少”比任何非空的范围内.原文:An empty range is lexicographically less than any non-empty range.
- 两个空的范围是字典“等于”.原文:Two empty ranges are lexicographically equal.
目录 |
[编辑] 参数
first1, last1 | - | 检查的元素
原文: the first range of elements to examine |
first2, last2 | - | 第二次检查的元素
原文: the second range of elements to examine |
comp | - | comparison function which returns true if the first argument is less than the second. 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 | ||
-InputIt1, InputIt2 必须满足 InputIterator 的要求。
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[编辑] 返回值
true如果第一个范围是字典“”比第二少.
原文:
true if the first range is lexicographically less than the second.
[编辑] 复杂度
在大多数2·min(N1, N2)的比较操作的应用程序,其中N1 = std::distance(first1, last1)和N2 = std::distance(first2, last2).
原文:
At most 2·min(N1, N2) applications of the comparison operation, where N1 = std::distance(first1, last1) and N2 = std::distance(first2, last2).
[编辑] 可能的实现
版本一 |
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template<class InputIt1, class InputIt2> bool lexicographical_compare(InputIt1 first1, InputIt1 last1, InputIt2 first2, InputIt2 last2) { for ( ; (first1 != last1) && (first2 != last2); first1++, first2++ ) { if (*first1 < *first2) return true; if (*first2 < *first1) return false; } return (first1 == last1) && (first2 != last2); } |
版本二 |
template<class InputIt1, class InputIt2, class Compare> bool lexicographical_compare(InputIt1 first1, InputIt1 last1, InputIt2 first2, InputIt2 last2, Compare comp) { for ( ; (first1 != last1) && (first2 != last2); first1++, first2++ ) { if (comp(*first1, *first2)) return true; if (comp(*first2, *first1)) return false; } return (first1 == last1) && (first2 != last2); } |
[编辑] 示例
#include <algorithm> #include <iostream> #include <vector> #include <cstdlib> #include <ctime> int main() { std::vector<char> v1 {'a', 'b', 'c', 'd'}; std::vector<char> v2 {'a', 'b', 'c', 'd'}; std::srand(std::time(0)); while (!std::lexicographical_compare(v1.begin(), v1.end(), v2.begin(), v2.end())) { for (auto c : v1) std::cout << c << ' '; std::cout << ">= "; for (auto c : v2) std::cout << c << ' '; std::cout << '\n'; std::random_shuffle(v1.begin(), v1.end()); std::random_shuffle(v2.begin(), v2.end()); } for (auto c : v1) std::cout << c << ' '; std::cout << "< "; for (auto c : v2) std::cout << c << ' '; std::cout << '\n'; }
Possible output:
a b c d >= a b c d d a b c >= c b d a b d a c >= a d c b a c d b < c d a b