std::adjacent_difference

来自cppreference.com

 
 
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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adjacent_difference
partial_sum
C库
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C library
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Defined in header <numeric>
template< class InputIt, class OutputIt >

OutputIt adjacent_difference( InputIt first, InputIt last,

                                    OutputIt d_first );
(1)
template< class InputIt, class OutputIt, class BinaryOperation >

OutputIt adjacent_difference( InputIt first, InputIt last,
                                    OutputIt d_first,

                                    BinaryOperation op );
(2)
计算所述第二和第一元素的范围内[first, last)的每个相邻对之间的差异,并且将它们写入到的范围内开始,d_first + 1。未修改的副本,first被写入d_first。第一个版本使用operator-来计算的差异,第二个版本使用给定的二进制功能的op.
Original:
Computes the differences between the second and the first of each adjacent pair of elements of the range [first, last) and writes them to the range beginning at d_first + 1. Unmodified copy of first is written to d_first. The first version uses operator- to calculate the differences, the second version uses the given binary function op.
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相同的操作
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Equivalent operation:
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*(d_first)   = *first;
*(d_first+1) = (*first+1) - *(first);
*(d_first+2) = (*first+2) - *(first+1);
*(d_first+3) = (*first+3) - *(first+2);
...

目录

[编辑] 参数

first, last -
的范围内的元素
Original:
the range of elements
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d_first -
的目标范围的开头
Original:
the beginning of the destination range
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op - binary operation function object that will be applied.

The signature of the function should be equivalent to the following:

Ret fun(const Type1 &a, const Type2 &b);

The signature does not need to have const &.
The types  Type1 and  Type2 must be such that an object of type iterator_traits<InputIt>::value_type can be implicitly converted to both of them. The type  Ret must be such that an object of type OutputIt can be dereferenced and assigned a value of type  Ret. ​

Type requirements
-
InputIt must meet the requirements of InputIterator.
-
OutputIt must meet the requirements of OutputIterator.

[编辑] 返回值

它过去的最后一个元素的元素写的
Original:
It to the element past the last element written.
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[编辑] 复杂性

究竟(last - first) - 1应用程序的二进制运算
Original:
Exactly (last - first) - 1 applications of the binary operation
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[编辑] 可能的实现

First version
template<class InputIt, class OutputIt>
OutputIt adjacent_difference(InputIt first, InputIt last, 
                             OutputIt d_first)
{
    if (first == last) return d_first;
 
    typedef typename std::iterator_traits<InputIt>::value_type value_t;
    value_t acc = *first;
    *d_first = acc;
    while (++first != last) {
        value_t val = *first;
        *++d_first = val - acc;
        acc = std::move(val);
    }
    return ++d_first;
}
Second version
template<class InputIt, class T, class BinaryOperation>
OutputIt adjacent_difference(InputIt first, InputIt last, 
                             OutputIt d_first, BinaryOperation op)
{
    if (first == last) return d_first;
 
    typedef typename std::iterator_traits<InputIt>::value_type value_t;
    value_t acc = *first;
    *d_first = acc;
    while (++first != last) {
        value_t val = *first;
        *++d_first = op(val, acc);
        acc = std::move(val);
    }
    return ++d_first;
}

[编辑] 为例

下面的代码转换为偶数序列的重复数2与斐波那契数列的序列的序列转换.
Original:
The following code converts a sequence of even numbers to repetitions of the number 2 and converts a sequence of ones to a sequence of Fibonacci numbers.
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#include <numeric>
#include <vector>
#include <iostream>
#include <functional>
int main()
{
    std::vector<int> v{2, 4, 6, 8, 10, 12, 14, 16, 18, 20};
    std::adjacent_difference(v.begin(), v.end(), v.begin());
 
    for(auto n: v) {
        std::cout << n << ' ';
    }
    std::cout << '\n';
 
    v = {1, 1, 1, 1, 1, 1, 1, 1, 1, 1};
    std::adjacent_difference(v.begin(), v.end()-1, v.begin()+1, std::plus<int>()
 
    for(auto n: v) {
        std::cout << n << ' ';
    }
    std::cout << '\n';
}

Output:

2 2 2 2 2 2 2 2 2 2
1 1 2 3 5 8 13 21 34 55

[编辑] 另请参阅

计算的部分和一定范围的元素
Original:
computes the partial sum of a range of elements
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(函数模板) [edit]
总结了一系列的元素
Original:
sums up a range of elements
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(函数模板) [edit]