std::partition
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| Defined in header <algorithm>
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| template< class BidirIt, class UnaryPredicate > BidirectionalIterator partition( BidirIt first, BidirIt last, |
（至 C++11） （C++11 起） |
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重新排序的范围
[first, last)在这样一种方式中的元素，所有元素的谓词p回报true之前的元素为谓词p回报false。不保留元素的相对顺序. Original:
Reorders the elements in the range
[first, last) in such a way that all elements for which the predicate p returns true precede the elements for which predicate p returns false. Relative order of the elements is not preserved. The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
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目录 |
[编辑] 参数
| first, last | - | 范围内的元素进行重新排序
Original: the range of elements to reorder The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. | |||||||||
| p | - | unary predicate which returns true 如果该元素的，要责令之前的其他元素 . Original: if the element should be ordered before other elements The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. The signature of the predicate function should be equivalent to the following:
The signature does not need to have const &, but the function must not modify the objects passed to it. | |||||||||
| Type requirements | |||||||||||
-BidirIt must meet the requirements of BidirectionalIterator.
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-ForwardIt must meet the requirements of ValueSwappable and ForwardIterator. However, the operation is more efficient if ForwardIt also satisfies the requirements of BidirectionalIterator
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[编辑] 返回值
第二组的第一个元素的迭代器，.
Original:
Iterator to the first element of the second group.
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
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[编辑] 复杂性
究竟last-first应用程序的谓词和最last-first掉期。
ForwardIt符合要求的BidirectionalIterator(last-first)/2掉期做.Original:
Exactly last-first applications of the predicate and at most last-first swaps. If
ForwardIt meets the requirements of BidirectionalIterator at most (last-first)/2 swaps are done.The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
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[编辑] 可能的实现
template<class BidirIt, class UnaryPredicate> BidirIt partition(BidirIt first, BidirIt last, UnaryPredicate p) { while (1) { while ((first != last) && p(*first)) { ++first; } if (first == last--) break; while ((first != last) && !p(*last)) { --last; } if (first == last) break; std::swap(*first++, *last); } return first; } |
[编辑] 为例
#include <algorithm> #include <functional> #include <iostream> #include <iterator> #include <vector> bool is_even(int i) { return i % 2 == 0; } int main() { std::vector<int> v; for (int i = 0; i < 10; ++i) v.push_back(i); std::cout << "Original vector:\n "; std::copy(v.begin(), v.end(), std::ostream_iterator<int>(std::cout, " ")); // Partition the vector std::vector<int>::iterator p = std::partition(v.begin(), v.end(), std::ptr_fun(is_even)); std::cout << "\nPartitioned vector:\n "; std::copy(v.begin(), v.end(), std::ostream_iterator<int>(std::cout, " ")); std::cout << "\nBefore partition:\n "; std::copy(v.begin(), p, std::ostream_iterator<int>(std::cout, " ")); std::cout << "\nAfter partition:\n "; std::copy(p, v.end(), std::ostream_iterator<int>(std::cout, " ")); }
Possible output:
Original vector:
0 1 2 3 4 5 6 7 8 9
Partitioned vector:
0 8 2 6 4 5 3 7 1 9
Before partition:
0 8 2 6 4
After partition:
5 3 7 1 9[编辑] 另请参阅
| （C++11） |
确定的范围被划分给定的谓词 Original: determines if the range is partitioned by the given predicate The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. （函数模板） |
| 将元素分为两组，同时保留其相对顺序 Original: divides elements into two groups while preserving their relative order The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. （函数模板） | |
