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vector

vector のパフォーマンスを調査するサンプルです。
・Util.h
// パクリ：http://msdn.microsoft.com/ja-jp/library/system.diagnostics.stopwatch(v=vs.80).aspx
class Stopwatch {
 private:
  unsigned long long frequency_;
  unsigned long long elapsed_;
  unsigned long long start_;
  bool is_running_;
 public:
  Stopwatch();

  void Start();
  void Stop();
  void Reset();
  unsigned long long GetElapsedMilliseconds();
  unsigned long long GetElapsedSeconds();
  unsigned long long GetElapsedTicks();
  unsigned long long GetFrequency();
};
 
・Util.cc
#include "Util.h"

#include <assert.h>
#include <Windows.h>

Stopwatch::Stopwatch() {
  LARGE_INTEGER i;
  if(::QueryPerformanceFrequency(&i) == 0) {
    assert(false);
  }
  frequency_ = i.QuadPart;

  Reset();
}

void Stopwatch::Start() {
  LARGE_INTEGER i;
  ::QueryPerformanceCounter(&i);
  start_ = i.QuadPart;
  is_running_ = true;
}

void Stopwatch::Stop() {
  if(is_running_) {
    LARGE_INTEGER i;
    ::QueryPerformanceCounter(&i);
    elapsed_ += i.QuadPart - start_;
    is_running_ = false;
  }
}

void Stopwatch::Reset() {
  elapsed_ = start_ = 0;
  is_running_ = false;
}

unsigned long long Stopwatch::GetElapsedMilliseconds() {
  if (is_running_) {
    LARGE_INTEGER i;
    ::QueryPerformanceCounter(&i);
    return (elapsed_ + i.QuadPart - start_) * 1000 / frequency_;
  } else {
    return elapsed_ * 1000 / frequency_;
  }
}

unsigned long long Stopwatch::GetElapsedSeconds() {
  return GetElapsedTicks() / frequency_;
}

unsigned long long Stopwatch::GetElapsedTicks() {
  if (is_running_) {
    LARGE_INTEGER i;
    ::QueryPerformanceCounter(&i);
    return elapsed_ + i.QuadPart - start_;
  } else {
    return elapsed_;
  }
}

unsigned long long Stopwatch::GetFrequency() 
{
  return frequency_;
}

・main.cc
#include "Util.h"

#include <stdio.h>
#include <vector>
#include <iostream>

void main(void)
{
  int sum;
  Stopwatch sw;
  std::vector<int> v(10000);
  int a[10000];
  int* ha = new int[10000];

  sum = 0;
  sw.Start();
  for(int i = 0; i < 10000; i++) {
    v[i] = i * 2;
  }
  for(int i = 0; i < 10000; i++) {
    sum += v.at(i);
  }
  sw.Stop();
  std::cout << "vector=" << sw.GetElapsedTicks() << std::endl;

  sum = 0;
  //sw.Reset();
  sw.Start();
  for(int i = 0; i < 10000; i++) {
    a[i] = i * 2;
  }
  for(int i = 0; i < 10000; i++) {
    if(0 <= i && i < 10000) {
      sum += a[i];
    }
  }
  sw.Stop();
  std::cout << "array=" << sw.GetElapsedTicks() << std::endl;

  sum = 0;
  //sw.Reset();
  sw.Start();
  for(int i = 0; i < 10000; i++) {
    ha[i] = i * 2;
  }
  for(int i = 0; i < 10000; i++) {
    if(0 <= i && i < 10000) {
      sum += ha[i];
    }
  }
  sw.Stop();
  std::cout << "harray=" << sw.GetElapsedTicks() << std::endl;

  std::cout << "freq=" << sw.GetFrequency() << std::endl;
}