for_each.cpp

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#include <algorithm>    // for for_each
#include <functional>   // for less, unary_function
#include <iostream>     // for cout, endl
#include <set>          // for set
 
#include <examples.h>
 
 
// Function object that outputs its argument times x.
template <class Arg>
class out_times_x:  public std::unary_function<Arg, void>
{
    Arg multiplier;
public:
    out_times_x (const Arg &x) : multiplier (x) { }
 
    void operator() (const Arg &x) const {
        std::cout << x * multiplier << " " << std::endl;
    }
};
 
 
int main ()
{
    // Typedef for convenience.
    typedef std::set<int, std::less<int>, std::allocator<int> > sequence;
    
    sequence::value_type arr [] = { 1, 2, 3, 4, 5 };
 
    // Populate a sequence from arr.
    sequence s (arr, arr + sizeof arr / sizeof *arr);
 
    // Construct a function object.
    out_times_x<sequence::value_type> f2 (2);
  
    // Apply function object's operator() to each element.
    std::for_each (s.begin (), s.end (), f2);
  
    return 0;
}