std::adjacent_find

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算法库
功能
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Functions
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修改序列操作
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Non-modifying sequence operations
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all_of
any_of
none_of
(C++11)
(C++11)
(C++11)
for_each
count
count_if
mismatch
equal
修改序列操作
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Modifying sequence operations
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分区操作
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Partitioning operations
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is_partitioned(C++11)
partition
partition_copy(C++11)
排序操作(排序的区间)
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Sorting operations (on sorted ranges)
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is_sorted(C++11)
is_sorted_until(C++11)
sort
二进制搜索操作(排序的区间)
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Binary search operations (on sorted ranges)
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设置操作(排序的区间)
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Set operations (on sorted ranges)
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堆的操作
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Heap operations
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最小/最大操作
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Minimum/maximum operations
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数字操作
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Numeric operations
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C库
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C library
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Defined in header <algorithm>
template< class ForwardIt >
ForwardIt adjacent_find( ForwardIt first, ForwardIt last );
(1)
template< class ForwardIt, BinaryPredicate p >
ForwardIt adjacent_find( ForwardIt first, ForwardIt last, BinaryPredicate p );
(2)
搜索范围[first, last)为两个连续的相同元素。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:
Searches the range [first, last) for two consecutive identical elements. The first version uses operator== to compare the elements, the second version uses the given binary predicate p.
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目录

[编辑] 参数

first, last -
检查的元素
Original:
the range of elements to examine
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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.

[编辑] 返回值

一个迭代器相同的元素。如果没有这样的元素被发现,last返回
Original:
an iterator to the first of the identical elements. If no such elements are found, last is returned
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[编辑] 复杂性

完全(result - first)和小((last - 1) - first)应用的返回值是的谓词在那里,result.
Original:
Exactly the smaller of (result - first) and ((last - 1) - first) applications of the predicate where result is the return value.
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[编辑] 可能的实现

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

[编辑] 为例

下面的代码是找到一个对等效的整数的数组intergers .
Original:
The following code finds a pair of equivalent integers in an array of intergers.
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#include <algorithm>
#include <iostream>
 
int main()
{
    std::vector<int> v1{0, 1, 2, 3, 40, 40, 5};
 
    std::vector<int>::iterator result;
    result = std::adjacent_find(v1.begin(), v1.end());
 
    if (result == v1.end()) {
        std::cout << "no matching adjacent elements";
    } else {
        std::cout << "match at: " << std::distance(v1.begin(), result);
    }
}

Output:

match at: 4

[编辑] 另请参阅

removes consecutive duplicate elements in a range
(函数模板) [edit]