Standard C++ LibraryCopyright 1996, Rogue Wave Software, Inc.

NAME

  accumulate  - Accumulate 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);

DESCRIPTION

  accumulate 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 initial
  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.

COMPLEXITY

  accumulate performs exactly last-first applications of the binary operation
  (operator+ by default).

EXAMPLE

  //
  // accum.cpp
  //
   #include <numeric>   //for accumulate
   #include <vector>    //for vector
   #include <functional> //for times
   #include <iostream.h>

  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;
   }
  Output :
  For 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 need
  to always supply the Allocator template argument.  For instance you'll have
  to write:

  vector<int,allocator<int> >

  instead of:

  vector<int>

STANDARDS CONFORMANCE

  ANSI X3J16/ISO WG21 Joint C++ Committee



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