Re: [Mono-list] offtopic, but cool

Wed, 12 May 2004 05:41:34 -0700

Hi Cory,

In the C++ sample, you are passing the rect by value, so you are saving a copy in the list. In C# a reference to the object is used, so there is no copy-construction overhead.

You can change the list<rect> to a list<rect*>, but this way you have to manage the memory by yourlself.

[]
Mello



Cory Nelson wrote:
Just got done installing the VS.NET 2005 preview and did a small test.

I compared an ArrayList of Rectangles to a List<Rectangle>, and timed
inserting 1mil rects into each.  I also wrote an equivalent c++ app. 
Got some interesting results:

ArrayList: 265ms
List<Rectangle>: 62ms
list<rect>: 141ms

So it seems with generics .NET is finally faster than c++ (at least,
in this case).

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#region Using directives

using System;
using System.Collections;
using System.Collections.Generic;
using System.Drawing;

#endregion

namespace SpeedTest {
	class Program {
		static void Main(string[] args) {
			ArrayList al = new ArrayList();
			List<Rectangle> rl = new List<Rectangle>();
			DateTime start, end;

			GC.Collect();
			GC.WaitForPendingFinalizers();

			start = DateTime.Now;
			for (int i = 0; i < 1000000; i++)
				al.Add(new Rectangle(i, i, i, i));
			end = DateTime.Now;

			Console.WriteLine("Arraylist:       {0:F3}ms", (end-start).TotalMilliseconds);

			GC.Collect();
			GC.WaitForPendingFinalizers();

			start = DateTime.Now;
			for (int i = 0; i < 1000000; i++)
				rl.Add(new Rectangle(i, i, i, i));
			end = DateTime.Now;

			Console.WriteLine("List<Rectangle>:  {0:F3}ms", (end - start).TotalMilliseconds);
		}
	}
}

  

#include <list>
#include <iostream>
#include <ctime>
using namespace std;

struct rect {
	int x;
	int y;
	int width;
	int height;
};

int main(void) {
	list<rect> rl;

	clock_t start=clock();
	for(int i=0; i<1000000; i++) {
		rect r={i, i, i, i};
		rl.push_back(r);
	}
	clock_t end=clock();

	cout << "list<rect>: " << (((float)(end-start))/((float)CLOCKS_PER_SEC)*1000.0f) << "ms" << endl;

	return 0;
}

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