```
Standard C++ Library
Copyright 1998, Rogue Wave Software, Inc.

```

## NAME

```     adjacent_difference

- Outputs a sequence of the differences between each  adja-
cent pair of elements in a range.

```

## SYNOPSIS

```     #include <numeric>
template <class InputIterator, class OutputIterator>
InputIterator last,
OutputIterator result);
template <class InputIterator,
class OutputIterator,
class BinaryOperation>
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
adjacent_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  sup-
plying  the  plus  (+)  operator,  the  result  of  applying
adjacent_difference to {1,2,3,5} is the sequence {1,3,5,8}.

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  applying  adjacent_difference into the original
sequence.

```

## COMPLEXITY

```     This algorithm performs exactly (last-first)  -  1  applica-
tions of the default operation (-) or binary_op.

```

## EXAMPLE

```     //
//
#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)
//
//
//Calculate difference(s) using the times operator
//
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 Output

For 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  parame-
ters,  then you always need to supply the Allocator template
argument. For instance, you have to write:

vector<int,allocator<int> >

vector<int>

If your compiler does not support namespaces,  then  you  do
not need the using declaration for std.

```