title: C++ Array vs vector
body: <p>when using C++ vector, time spent is 718 milliseconds,
  while when I use Array, time is almost 0 milliseconds.</p>
  
  <p>Why so much performance difference?</p>
  
  <pre><code>int _tmain(int argc, _TCHAR* argv[])
  {
  const int size = 10000; 
  clock_t start, end; 
  start = clock();
  vector&lt;int&gt; v(size*size); 
  for(int i = 0; i &lt; size; i++)
  {  
      for(int j = 0; j &lt; size; j++)
      {   
          v[i*size+j] = 1;  
      } 
  } 
  end = clock();
  cout&lt;&lt; (end - start)
      &lt;&lt;" milliseconds."&lt;&lt;endl; // 718 milliseconds
  
  int f = 0;
  start = clock(); 
  int arr[size*size]; 
  for(int i = 0; i &lt; size; i++)
  {  
      for(int j = 0; j &lt; size; j++)
      {   
          arr[i*size+j] = 1;  
      } 
  } 
  end = clock();
  cout&lt;&lt; ( end - start)
      &lt;&lt;" milliseconds."&lt;&lt;endl; // 0 milliseconds
  return 0;
  }
  </code></pre>