STL Sample for the partial_sum FunctionLast reviewed: October 9, 1997Article ID: Q157393 |
The information in this article applies to:
SUMMARYThe sample code below illustrates how to use partial_sum STL function in Visual C++.
MORE INFORMATION
Required Header
#include <numeric> #include <functional> Prototype
template<class InputIterator, class OutputIterator> inline OutputIterator partial_sum(InputIterator first, InputIterator last, OutputIterator first2) template<class InputIterator, class OutputIterator, class BinaryOperator> inline OutputIterator partial_sum(InputIterator first, InputIterator last, OutputIterator first2, BinaryOperator binary_op)NOTE: The class/parameter names in the prototype may not match the version in the header file. Some have been modified to improve readability.
DescriptionAssigns to every iterator i in the range [result,result + (last - first)) a value correspondingly equal to ((...(*first + *(first + 1)) + ...) + *(first + (i - result)))
In other words, *(result+i) = init + *(first+0) + *(first+1) + ... + *(first+i)
Sample Code
/////////////////////////////////////////////////////////////////////// // // Compile options needed: /GX // // partial_sum.cpp : Demonstrates the use of partial_sum(). // // Description of partial_sum(first,last,first2,init) // partial_sum(first,last,first2,init,binary_op): // // Assigns to every iterator i in the range // [result,result + (last - first)) a value correspondingly equal to // ((...(*first + *(first + 1)) + ...) + *(first + (i - result))) // // - or - // // binary_op(binary_op(..., binary_op(*first, *(first + 1)),...), // *(first + (i - result))) // // In other words, // *(result+i) = init + *(first+0) + *(first+1) + ... + *(first+i) // // Written by Shaun Miller // of Microsoft Product Support Services, Languages Developer Support. // Copyright (c) 1996 Microsoft Corporation. All rights reserved. /////////////////////////////////////////////////////////////////////// #include <iostream> #include <numeric> #include <functional> #include <vector> #include <iterator>typedef vector < int, allocator < int > > IntArray; typedef ostream_iterator < int, char, char_traits<char> > IntOstreamIt;
void main (){ IntOstreamIt itOstream(cout," "); // Initialize the array IntArray rgI; for (int i=1; i<=10; i++) rgI.push_back(i); // Print the arrays cout << "Array: "; copy(rgI.begin(),rgI.end(),itOstream); cout << endl; // The result array must be at least the same size as the data array IntArray rgIresult(rgI.size()); // Compute the partial sum of the array partial_sum(rgI.begin(),rgI.end(),rgIresult.begin()); // Print the array of partial sums cout << "Array of partial sums: "; copy(rgIresult.begin(),rgIresult.end(),itOstream); cout << endl; // Compute the partial product of the array partial_sum(rgI.begin(),rgI.end(),rgIresult.begin(),times<int>()); // Print the array of partial products cout << "Array of partial products: "; partial_sum(rgIresult.begin(),rgIresult.end(),itOstream); cout << endl;} The program output is: Array: 1 2 3 4 5 6 7 8 9 10 Array of partial sums: 1 3 6 10 15 21 28 36 45 55 Array of partial products: 1 3 9 33 153 873 5913 46233 409113 4037913
REFERENCESVisual C++ Books On Line: Visual C++ Books:C/C++:Standard C++ Library Reference.
|
Additional query words: STL STLSample partial_sum
© 1998 Microsoft Corporation. All rights reserved. Terms of Use. |