.\" ident @(#)accumulate.3
.\" Standard Template Library
.\" $$RW_INSERT_HEADER "slyrs.man"
.TH accumulate 3C++ "02 Apr 1998" "Rogue Wave Software" "-"
.ce2
Standard C++ Library   
Copyright 1998, Rogue Wave Software, Inc.   

.SH NAME

\f2accumulate\fP

\ - Accumulates all elements within a range into a single value.



.SH  SYNOPSIS


.RE
.RS 0
#include <numeric>
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template <class InputIterator, class T>
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T accumulate (InputIterator first,
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.RS 13
InputIterator last,
.br
T init);
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template <class InputIterator,
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class T,
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class BinaryOperation>
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T accumulate (InputIterator first,
.RE
.RS 13
InputIterator last,
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T init,
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BinaryOperation binary_op);



.SH  DESCRIPTION


accumulate applies a binary operation to \f2init\fP and each value in the range \f2[first,last).\fP The result of each operation is returned in \f2init\fP. 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 \f2acc\fP with the initial value \f2init\fP and then modifying it with \f2acc = acc + *i \fPor \f2acc = binary_op(acc, *i)\fP for every iterator \f2i\fP in the range \f2[first, last)\fP in order. If the sequence is empty, accumulate returns \f2init\fP.

\f2binary_op\fP should not have side effects.



.SH  COMPLEXITY


accumulate performs exactly \f2last-first\fP applications of the binary operation (\f2operator+ \fPby default).



.SH  EXAMPLE



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//
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// accum.cpp
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//
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#include <numeric>   //for accumulate
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#include <vector>    //for vector
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#include <functional> //for times
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#include <iostream>
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using namespace std;
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int main()
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{
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//
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//Typedef for vector iterators
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//
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typedef vector<int>::iterator iterator;
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//
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//Initialize a vector using an array of ints
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//
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int d1[10] = {1,2,3,4,5,6,7,8,9,10};
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vector<int> v1(d1, d1+10);
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//
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//Accumulate sums and products
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//
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int sum = accumulate(v1.begin(), v1.end(), 0);
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int prod = accumulate(v1.begin(), v1.end(), 
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1, times<int>());
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//
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//Output the results
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//
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cout << "For the series: ";
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for(iterator i = v1.begin(); i != v1.end(); i++)
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cout << *i << " ";
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cout << " where N = 10." << endl;
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cout << "The sum = (N*N + N)/2 = " << sum << endl;
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cout << "The product = N! = " << prod << endl;
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return 0;
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}

.br
.RE
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Program Output



.RE
.RS 0

.br
For the series: 1 2 3 4 5 6 7 8 9 10  where N = 10.
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The sum = (N*N + N)/2 = 55
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The product = N! = 3628800



.SH  WARNINGS


If your compiler does not support default template parameters, then you always need to supply the \f2Allocator\fP template argument. For instance, you have to write:


.br
vector<int,allocator<int> >

instead of:


.br
vector<int>

If your compiler does not support namespaces, then you do not need the using declaration for \f2std\fP.