Using a function object for operation counting, first version : Functor « Development « C++ Tutorial

Home
C++ Tutorial
1.Language Basics
2.Data Types
3.Operators statements
4.Array
5.Development
6.Exceptions
7.Function
8.Structure
9.Class
10.Operator Overloading
11.Pointer
12.File Stream
13.template
14.STL Introduction
15.string
16.vector
17.list
18.bitset
19.set multiset
20.valarray
21.queue stack
22.deque
23.map multimap
24.STL Algorithms Modifying sequence operations
25.STL Algorithms Non modifying sequence operations
26.STL Algorithms Binary search
27.STL Algorithms Sorting
28.STL Algorithms Merge
29.STL Algorithms Min Max
30.STL Algorithms Iterator
31.STL Algorithms Heap
32.STL Algorithms Helper
C / ANSI-C
C Tutorial
C++
Visual C++ .NET
C++ Tutorial » Development » Functor 
5.15.5.Using a function object for operation counting, first version
//Revised from
//STL Tutorial and Reference Guide C++ Programming with the Standard Template L
ibrary, 2nd Edition
//by David R. Musser (Author), Atul Saini (Author)
//# Publisher: Addison-Wesley Pub (Sd) (March 1996)
//# Language: English
//# ISBN-10: 0201633981
//# ISBN-13: 978-0201633986


#include <iostream>
#include <iomanip>
#include <cassert>
#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() { }
  bool operator()(const T& x, const T& y) {
        ++counter;
        return x < y;
  }
  long report() const {return counter;}
  static long 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 << comp_counter.report() << endl;
  }
  return 0;
}
11846
26397
56776
125715
271505
596740
1235889
2727581
5.15.Functor
5.15.1.Functor
5.15.2.Functor compose 2
5.15.3.Functor compose 3
5.15.4.Using a function object for operation counting, second version
5.15.5.Using a function object for operation counting, first version
5.15.6.Demonstrating function pointer passing
www.java2java.com | Contact Us
Copyright 2009 - 12 Demo Source and Support. All rights reserved.
All other trademarks are property of their respective owners.