partial_sum (STL Samples)
Illustre comment utiliser la fonction de bibliothèque de types (STL) Standard de partial_sum dans Visual C++.
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
)
Notes
[!REMARQUE]
Les noms de classes/paramètre dans le prototype ne correspondent pas à la version du fichier d'en-tête.certains ont été modifiés pour améliorer la lisibilité.
assigne à chaque itérateur i dans la plage [résultat,résultat + (Last - First)) une valeur également égale à ((… (*First + * (First + 1)) +…) + * (First + (I - résultat))) - ou - Binary_Op(Binary_Op(…, Binary_Op(*First, * (First + 1)),…), * (First + (I - résultat))).En d'autres termes, * (résultat + i)= init + * (premier + 0) + * (premier + 1) +…+ * (premier + i).
Exemple
// partial_sum.cpp
// compile with: /EHsc
// 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)
///////////////////////////////////////////////////////////////////////
#include <iostream>
#include <numeric>
#include <functional>
#include <vector>
#include <iterator>
using namespace std;
typedef vector < int > IntArray;
typedef ostream_iterator < int, char, char_traits<char> > IntOstreamIt;
int 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(),multiplies<int>());
// Print the array of partial products
cout << "Array of partial products: [ ";
partial_sum(rgIresult.begin(),rgIresult.end(),itOstream);
cout << "]" << endl;
}
Sortie
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 ]
Configuration requise
en-tête : <numeric>