Функциональные объекты

#include <iostream>
#include <vector>
#include <algorithm>
#include <functional>
 
using namespace std;
 
template <typename T>
class less_with_count : public binary_function <T, T, bool> {
    public:
        less_with_count () {}
        static long counter;
        bool operator () (const T& x, const T& y) {
            ++counter;
            return x < y;
        }
        long report () const { return counter; }
};
 
template < typename T >
long less_with_count <T> :: counter = 0;
 
int main () {
    const long N1 = 1000, N2 = 128000;
    for (long N = N1; N <= N2; N *= 2) {
        vector <int> vector1;
        for (int k = 0; k < N; ++k) vector1.push_back (k);
        
    random_shuffle (vector1.begin (), vector1.end ());
    less_with_count <int> comp_counter;
    less_with_count <int> :: counter = 0;
    
    sort (vector1.begin (), vector1.end (), comp_counter);
    cout << "The size is: " << N << ", "
         << comp_counter.report () << " comparisons commited\n";
    }
    
    return 0;
}

: public binary_function <T, T, bool>

template < typename T >
long less_with_count <T> :: counter = 0;

less_with_count <int> :: counter = 0;

: public binary_function <T, T, bool>