accumulate(3C++) - accumulate(3C++)
Standard C++ Library Copyright 1998, Rogue Wave Software, Inc.
NAMEaccumulate
- Accumulates all elements within a range into a single value.
SYNOPSIS
#include <numeric>
template <;class InputIterator, class T>
T accumulate (InputIterator first,
InputIterator last,
T init);
template <;class InputIterator,
class T,
class BinaryOperation>
T accumulate (InputIterator first,
InputIterator last,
T init,
BinaryOperation binary_op);
DESCRIPTIONaccumulate applies a binary operation to init and each value in the
range [first,last). The result of each operation is returned in init.
This process aggregates the result of performing the operation on every
element of the sequence into a single value.
Accumulation is done by initializing the accumulator acc with the ini‐
tial value init and then modifying it with acc = acc + *i or acc =
binary_op(acc, *i) for every iterator i in the range [first, last) in
order. If the sequence is empty, accumulate returns init.
binary_op should not have side effects.
COMPLEXITYaccumulate performs exactly last-first applications of the binary oper‐
ation (operator+ by default).
EXAMPLE
//
// accum.cpp
//
#include <numeric> //for accumulate
#include <vector> //for vector
#include <functional> //for times
#include <iostream>
using namespace std;
int main()
{
//
//Typedef for vector iterators
//
typedef vector<int>::iterator iterator;
//
//Initialize a vector using an array of ints
//
int d1[10] = {1,2,3,4,5,6,7,8,9,10};
vector<int> v1(d1, d1+10);
//
//Accumulate sums and products
//
int sum = accumulate(v1.begin(), v1.end(), 0);
int prod = accumulate(v1.begin(), v1.end(),
1, times<int>());
//
//Output the results
//
cout << "For the series: ";
for(iterator i = v1.begin(); i != v1.end(); i++)
cout << *i << " ";
cout << " where N = 10." << endl;
cout << "The sum = (N*N + N)/2 = " << sum << endl;
cout << "The product = N! = " << prod << endl;
return 0;
}
Program OutputFor the series: 1 2 3 4 5 6 7 8 9 10 where N = 10.
The sum = (N*N + N)/2 = 55
The product = N! = 3628800
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 accumulate(3C++)
