listvsset.cpp

Thinking in c++ 2nd edition,c++编程思想（第2版）

//: C07:ListVsSet.cpp
// From "Thinking in C++, Volume 2", by Bruce Eckel & Chuck Allison.
// (c) 1995-2004 MindView, Inc. All Rights Reserved.
// See source code use permissions stated in the file 'License.txt',
// distributed with the code package available at www.MindView.net.
// Comparing list and set performance.
#include <algorithm>
#include <cstdlib>
#include <ctime>
#include <iostream>
#include <iterator>
#include <list>
#include <set>
#include "PrintContainer.h"
using namespace std;

class Obj {
  int a[20]; // To take up extra space
  int val;
public:
  Obj() : val(rand() % 500) {}
  friend bool
  operator<(const Obj& a, const Obj& b) {
    return a.val < b.val;
  }
  friend bool
  operator==(const Obj& a, const Obj& b) {
    return a.val == b.val;
  }
  friend ostream&
  operator<<(ostream& os, const Obj& a) {
    return os << a.val;
  }
};

struct ObjGen {
  Obj operator()() { return Obj(); }
};

int main() {
  const int SZ = 5000;
  srand(time(0));
  list<Obj> lo;
  clock_t ticks = clock();
  generate_n(back_inserter(lo), SZ, ObjGen());
  lo.sort();
  lo.unique();
  cout << "list:" << clock() - ticks << endl;
  set<Obj> so;
  ticks = clock();
  generate_n(inserter(so, so.begin()),
    SZ, ObjGen());
  cout << "set:" << clock() - ticks << endl;
  print(lo);
  print(so);
} ///:~