std::unique

 

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算法库

功能 Original: Functions The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
修改序列操作 Original: Non-modifying sequence operations The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
all_of any_of none_of （C++11） （C++11） （C++11） for_each count count_if mismatch equal	find find_if find_if_not （C++11） find_end find_first_of adjacent_find search search_n
修改序列操作 Original: Modifying sequence operations The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
copy copy_if （C++11） copy_n （C++11） copy_backward move （C++11） move_backward （C++11） fill fill_n transform generate generate_n remove remove_if remove_copy remove_copy_if	replace replace_if replace_copy replace_copy_if swap swap_ranges iter_swap reverse reverse_copy rotate rotate_copy random_shuffle shuffle   （C++11） unique unique_copy
分区操作 Original: Partitioning operations The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
is_partitioned （C++11） partition partition_copy （C++11）	stable_partition partition_point （C++11）
排序操作（排序的区间） Original: Sorting operations (on sorted ranges) The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
is_sorted （C++11） is_sorted_until （C++11） sort	partial_sort partial_sort_copy stable_sort nth_element
二进制搜索操作（排序的区间） Original: Binary search operations (on sorted ranges) The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
lower_bound upper_bound	binary_search equal_range
设置操作（排序的区间） Original: Set operations (on sorted ranges) The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
merge inplace_merge includes	set_difference set_intersection set_symmetric_difference set_union
堆的操作 Original: Heap operations The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
is_heap is_heap_until （C++11） make_heap	push_heap pop_heap sort_heap
最小/最大操作 Original: Minimum/maximum operations The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
max max_element min min_element minmax （C++11） minmax_element （C++11）	lexicographical_compare is_permutation （C++11） next_permutation prev_permutation
数字操作 Original: Numeric operations The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
iota （C++11） accumulate inner_product	adjacent_difference partial_sum
C库 Original: C library The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
qsort	bsearch

 

Defined in header <algorithm>
template< class ForwardIt > ForwardIt unique( ForwardIt first, ForwardIt last );	(1)
template< class ForwardIt, class BinaryPredicate > ForwardIt unique( ForwardIt first, ForwardIt last, BinaryPredicate p );	(2)

删除所有连续重复的元素的范围[first, last)。卸下做是通过移动的范围内，在需要的时候在这样一种方式，要被擦除的元素将被覆盖。只有相等的元素的每个组中的第一个元素的在左边。元素之间的旧的和新的结束或范围保持不变。的第一个版本使用operator==比较的元素，第二个版本使用给定的二元谓词p.

Original:

Removes all consecutive duplicate elements from the range [first, last). Removing is done by shifting the range when needed in such a way that elements to be erased are overwritten. Only the first element in each group of equal elements is left. The elements between the old and the new end or the range are left intact. The first version uses operator== to compare the elements, the second version uses the given binary predicate p.

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参数

first, last	-	元素的范围内进行处理 Original: the range of elements to process The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
p	-	binary predicate which returns ​true if the elements should be treated as equal. The signature of the predicate function should be equivalent to the following:  bool pred(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.
- The type of dereferenced ForwardIt must meet the requirements of MoveAssignable.

返回值

前向迭代器新的范围

Original:

Forward iterator to the new end of the range

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可能的实现

First version
template<class ForwardIt> ForwardIt unique(ForwardIt first, ForwardIt last) { if (first == last) return last;   ForwardIt result = first; while (++first != last) { if (!(*result == *first)) { *(++result) = *first; } } return ++result; }
Second version
template<class ForwardIt, class BinaryPredicate> ForwardIt unique(ForwardIt first, ForwardIt last, BinaryPredicate p) { if (first == last) return last;   ForwardIt result = first; while (++first != last) { if (!p(*result, *first)) { *(++result) = *first; } } return ++result; }

为例

下面的代码将删除所有连续相等的元素的向量整数.

Original:

The following code removes all consecutive equivalent elements from a vector of integers.

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#include <iostream>
#include <algorithm>
#include <vector>
 
int main() 
{
    std::vector<int> v{1, 2, 2, 2, 3, 3, 2, 2, 1};
    std::vector<int>::iterator last;
 
    last = std::unique(v.begin(), v.end()); // 1 2 3 2 1 3 2 2 1
                                            //           ^
    for (std::vector<int>::iterator it = v.begin(); it != last; ++it) {
        std::cout << *it << " ";
    }
    std::cout << "\n";
}

Output:

1 2 3 2 1

复杂性

线性first和last之间的距离

Original:

linear in the distance between first and last

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另请参阅

adjacent_find	查找彼此相邻的两个相同（或其它的关系）的元素 （函数模板）
unique_copy	删除区间内连续重复的元素并复制 （函数模板）