adjacent_difference(3C++) - adjacent_difference(3C++)
Standard C++ Library Copyright 1998, Rogue Wave Software, Inc.
NAMEadjacent_difference
- Outputs a sequence of the differences between each adjacent pair of
elements in a range.
SYNOPSIS
#include <numeric>
template <class InputIterator, class OutputIterator>
OutputIterator adjacent_difference (InputIterator first,
InputIterator last,
OutputIterator result);
template <class InputIterator,
class OutputIterator,
class BinaryOperation>
OutputIterator adjacent_difference (InputIterator first,
InputIterator last,
OutputIterator result,
BinaryOperation bin_op);
DESCRIPTION
Informally, adjacent_difference fills a sequence with the differences
between successive elements in a container. The result is a sequence in
which the first element is equal to the first element of the sequence
being processed, and the remaining elements are equal to the calculated
differences between adjacent elements. For instance, applying adja‐
cent_difference to {1,2,3,5} produces a result of {1,1,1,2}.
By default, subtraction is used to compute the difference, but you can
supply any binary operator. The binary operator is then applied to
adjacent elements. For example, by supplying the plus (+) operator, the
result of applying adjacent_difference to {1,2,3,5} is the sequence
{1,3,5,8}.
Formally,_adjacent_difference assigns to every element referred to by
iterator i in the range [result + 1, result + (last - first)) a value
equal to the appropriate one of the following:
*(first + (i - result)) - *(first + (i - result) - 1)
or
binary_op (*(first + (i - result)),
*(first + (i - result) - 1))
result is assigned the value of *first.binary_op should not have side effects.adjacent_difference returns result + (last - first).
result can be equal to first. This allows you to place the results of applyingadjacent_difference into the original sequence.COMPLEXITY
This algorithm performs exactly (last-first) - 1 applications of the
default operation (-) or binary_op.
EXAMPLE
//
// adj_diff.cpp
//
#include<numeric> //For adjacent_difference
#include<vector> //For vector
#include<functional> //For times
#include <iostream>
using namespace std;
int main()
{
//
//Initialize a vector of ints from an array
//
int arr[10] = {1,1,2,3,5,8,13,21,34,55};
vector<int> v(arr,arr+10);
//
//Two uninitialized vectors for storing results
//
vector<int> diffs(10), prods(10);
//
//Calculate difference(s) using default operator (minus)
//
adjacent_difference(v.begin(),v.end(),diffs.begin());
//
//Calculate difference(s) using the times operator
//
adjacent_difference(v.begin(), v.end(), prods.begin(),
times<int>());
//
//Output the results
//
cout << "For the vector: " << endl << " ";
copy(v.begin(),v.end(),
ostream_iterator<int,char>(cout," "));
cout << endl << endl;
cout << "The differences between adjacent elements are: "
<< endl << " ";
copy(diffs.begin(),diffs.end(),
ostream_iterator<int,char>(cout," "));
cout << endl << endl;
cout << "The products of adjacent elements are: "
<< endl << " ";
copy(prods.begin(),prods.end(),
ostream_iterator<int,char>(cout," "));
cout << endl;
return 0;
Program OutputFor the vector:
1 1 2 3 5 8 13 21 34 55
The differences between adjacent elements are:
1 0 1 1 2 3 5 8 13 21
The products of adjacent elements are:
1 1 2 6 15 40 104 273 714 1870
WARNINGS
If your compiler does not support default template parameters, then you
always need to supply the Allocator template argument. For instance,
you have to write:
vector<int,allocator<int> >
instead of:vector<int>
If your compiler does not support namespaces, then you do not need the using
declaration for std.Rogue Wave Software 02 Apr 1998 adjacent_difference(3C++)