inner_product.cpp

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#include <algorithm>     // for copy()
#include <functional>    // for plus, minus
#include <iostream>      // for cout, endl
#include <iterator>      // for ostream_iterator
#include <list>          // for list
#include <numeric>       // for inner_product()
#include <vector>        // for vector
 
#include <examples.h>
 
 
int main ()
{
    typedef std::list<int, std::allocator<int> >                      List;
    typedef std::vector<int, std::allocator<int> >                    Vector;
    typedef std::ostream_iterator<int, char, std::char_traits<char> > os_iter;
 
    // Initialize a list and a vector using arrays of ints.
    int a1[] = { 6, -3, -2 };
    int a2[] = { -2, -3, -2 };
 
    List   l (a1, a1 + sizeof a1 / sizeof *a1);
    Vector v (a2, a2 + sizeof a2 / sizeof *a2);
 
    // Calculate the inner product of the two sets of values.
    List::value_type prod = std::inner_product (l.begin (), l.end (),
                                                v.begin (), 0);
 
    // Calculate a wacky inner product using the same values.
    List::value_type wacky =
        std::inner_product (l.begin (), l.end (), v.begin (), 0, 
                            std::plus<List::value_type>(),
                            std::minus<List::value_type>());
    // Print the output.
    std::cout << "For the sets of numbers: { ";
    std::copy (v.begin (), v.end (), os_iter (std::cout, " "));
 
    std::cout << "} and { ";
    std::copy (l.begin (), l.end (), os_iter (std::cout, " "));
 
    std::cout << "}\nThe inner product is: " << prod
              << "\nThe wacky result is:  " << wacky
              << std::endl;
 
    return 0;
}