The Weird and The Wonderful

Richard Deeming10-Dec-13 5:58

10-Dec-13 5:58

GuyThiebaut wrote:
I should have coded:

C#
if (item.Substring(0, 3).ToLower() != "PF_".ToLower())

I hope that's a good example of sarcasm! Poke tongue | ;-P

if (string.Compare(item, 0, "PF_", 0, 3, StringComparison.OrdinalIgnoreCase) != 0)

"These people looked deep within my soul and assigned me a number based on the order in which I joined."
- Homer

GuyThiebaut10-Dec-13 6:00

GuyThiebaut

10-Dec-13 6:00

Yes it's self satire... honestly...

“That which can be asserted without evidence, can be dismissed without evidence.”

― Christopher Hitchens

BobJanova10-Dec-13 6:40

BobJanova

10-Dec-13 6:40

If we're going for doing it right of course the answer is

if(item.StartsWith("PF_", StringComparison.OrdinalIgnoreCase)) ...

Richard Deeming10-Dec-13 6:50

10-Dec-13 6:50

Well, if you will insist on writing code that other people can understand and maintain... Roll eyes | :rolleyes:

"These people looked deep within my soul and assigned me a number based on the order in which I joined."
- Homer

BobJanova10-Dec-13 6:59

BobJanova

10-Dec-13 6:59

I'm sorry I meant

if(1600548864 == (*(int*)&item.ToLower()) << 8) ...

Richard Deeming10-Dec-13 7:01

10-Dec-13 7:01

That's better! Laugh | :laugh:

"These people looked deep within my soul and assigned me a number based on the order in which I joined."
- Homer

OriginalGriff10-Dec-13 8:34

10-Dec-13 8:34

Nasty! Unsafe code...
Please, try to avoid it, especially when it can be done without it so much more clearly:

if (((BitConverter.ToInt32(Encoding.ASCII.GetBytes(item), 0) & 6250335) ^ 6243920) == 0)

CDP180210-Dec-13 17:09

CDP1802

10-Dec-13 17:09

Clearly a functional language will magically make this far better:

((xum 567 487) (map item (lambda x (find (xor x (and y z)) (encode pi 49)))

The language is JavaScript. that of Mordor, which I will not utter here

I hold an A-7 computer expert classification, Commodore. I'm well acquainted with Dr. Daystrom's theories and discoveries. The basic design of all our ship's computers are JavaScript.

OriginalGriff10-Dec-13 21:20

10-Dec-13 21:20

CDP1802 wrote:
((xum 567 487) (map item (lambda x (find (xor x (and y z)) (encode pi 49)))
The language is JavaScript. that of Mordor, which I will not utter here

Man!

Javascript has changed!

Argonia10-Dec-13 20:36

10-Dec-13 20:36

if(String.Equals(string1, string2, StringComparison.OrdinalIgnoreCase))
{
    ...
}

is faster than string.Compare

Please kill me now or erase any information about c# from my head.

Microsoft ... the only place where VARIANT_TRUE != true

Richard Deeming11-Dec-13 2:27

11-Dec-13 2:27

Are you sure? They both use a virtually identical approach behind the scenes.

And since the original code is only comparing the first three characters of the item string, you'd have to use Substring to create a new string before you could call Equals, which would almost certainly be slower.

"These people looked deep within my soul and assigned me a number based on the order in which I joined."
- Homer

OriginalGriff11-Dec-13 3:00

11-Dec-13 3:00

Yes!

string string1 = File.ReadAllText(@"D:\Temp\MyText.txt");
string string2 = File.ReadAllText(@"D:\Temp\MyText.txt");
int x = 0;
Stopwatch sw1 = new Stopwatch();
sw1.Start();
for (int i = 0; i < 1000; i++)
    {
    if (String.Equals(string1, string2, StringComparison.OrdinalIgnoreCase))
        {
        x++;
        }
    }
sw1.Stop();
Console.WriteLine(x);
x = 0;
Stopwatch sw2 = new Stopwatch();
sw2.Start();
for (int i = 0; i < 1000; i++)
    {
    if (String.Compare(string1, string2, true) == 0)
        {
        x++;
        }
    }
sw2.Stop();
Console.WriteLine(x);
Console.WriteLine("{0}:{1}", sw1.ElapsedMilliseconds, sw2.ElapsedMilliseconds);

(The file is one of my standard test files: 1.6MB of Ipsum Lorem paragraphs)
Results:

1000
1000
1716:4071

Richard Deeming11-Dec-13 3:27

11-Dec-13 3:27

That's strange - on my computer, with a similar sized text file, Compare(string, string, bool) is consistently faster:

1000
1000
13997:3431

I'm running .NET 4.5.1 on Win7 x64.

Also, string.Compare(s1, s2, true) isn't the same as string.Equals(s1, s2, StringComparison.OrdinalIgnoreCase); it's equivalent to StringComparison.CurrentCultureIgnoreCase. Try using string.Compare(s1, s2, StringComparison.OrdinalIgnoreCase) instead.

"These people looked deep within my soul and assigned me a number based on the order in which I joined."
- Homer

OriginalGriff11-Dec-13 3:46

11-Dec-13 3:46

Interesting: I'm also Win7/64, but .NET 4.0 rather than 4.5.
Adding OrdinalIgnoreCase:

string string1 = File.ReadAllText(@"D:\Temp\MyText.txt");
string string2 = File.ReadAllText(@"D:\Temp\MyText.txt");
int x = 0;
Stopwatch sw1 = new Stopwatch();
sw1.Start();
for (int i = 0; i < 1000; i++)
    {
    if (String.Equals(string1, string2, StringComparison.OrdinalIgnoreCase))
        {
        x++;
        }
    }
sw1.Stop();
Console.WriteLine(x);
x = 0;
Stopwatch sw2 = new Stopwatch();
sw2.Start();
for (int i = 0; i < 1000; i++)
    {
    if (String.Compare(string1, string2, true) == 0)
        {
        x++;
        }
    }
sw2.Stop();
Console.WriteLine(x);
x = 0;
Stopwatch sw3 = new Stopwatch();
sw3.Start();
for (int i = 0; i < 1000; i++)
    {
    if (String.Compare(string1, string2, StringComparison.OrdinalIgnoreCase) == 0)
        {
        x++;
        }
    }
sw3.Stop();
Console.WriteLine(x);
Console.WriteLine("{0}:{1}:{2}", sw1.ElapsedMilliseconds, sw2.ElapsedMilliseconds,sw3.ElapsedMilliseconds);

gives results similar to yours:

1000
1000
1000
1694:4087:1684

I'm surprised there is such a difference in performance between our machines: mine isn't anywhere near state of the art - more state of the ark! Laugh | :laugh:

Argonia11-Dec-13 3:57

11-Dec-13 3:57

Ah, the mysteries of M$. Our life will be so empty and boring without them.

The same code (Sorry Griff i should pay you author rights)

the result was

1000
1000
1000
4359:2216:4383

.Net 4.5 Win 7/64

Microsoft ... the only place where VARIANT_TRUE != true

OriginalGriff11-Dec-13 4:57

11-Dec-13 4:57

Out of interest, are you building for "Any CPU", "x64" or "x32"?
Mine is built "x32" because that's what the app I shoved the code in is built for.

Argonia11-Dec-13 5:04

11-Dec-13 5:04

The results i pasted was with "Any CPU"
x64

1000
1000
1000
5363:2199:5338

x86

1000
1000
1000
4530:2305:4519

Visual studio Premium 2012 version 11 with Update 3, Win7/64, .NET 4.5.50709 to be exact

Anyway i don't see how he gets ~14 seconds for String.Equals

P.S i should say i have problems with my hard at work. I am waiting for it to die. This also can affect the pasted data. I wonder what the results will be with reading from SSD
Note to myself : seconds comes after milliseconds not minutes. Stupid

Microsoft ... the only place where VARIANT_TRUE != true

modified 11-Dec-13 11:18am.

Richard Deeming11-Dec-13 5:13

11-Dec-13 5:13

It's milliseconds, so it was just under 14 seconds, not minutes! Poke tongue | ;-P

I'm running the code in LinqPad[^], and I've tried both with and without optimisations enabled, but it doesn't make a huge difference.

"These people looked deep within my soul and assigned me a number based on the order in which I joined."
- Homer

Argonia11-Dec-13 5:16

11-Dec-13 5:16

Yeah i know its in milliseconds but my upper processor forgot that after miliseconds seconds are next not minutes Big Grin | :-D

I am running it in debug mode with no optimisations.

Microsoft ... the only place where VARIANT_TRUE != true

Rob Grainger17-Dec-13 1:30

Rob Grainger

17-Dec-13 1:30

"I am running it in debug mode with no optimisations."

Why on earth try to benchmark code with no optimisations? Complete waste of time.

"If you don't fail at least 90 percent of the time, you're not aiming high enough."
Alan Kay.

Richard Deeming11-Dec-13 4:09

11-Dec-13 4:09

It must be .NET 4.5 - my machine's an early Vista-era dual-core.

"These people looked deep within my soul and assigned me a number based on the order in which I joined."
- Homer

Jörgen Andersson11-Dec-13 20:16

Jörgen Andersson

11-Dec-13 20:16

You'll have to redo the test using the same textfile. I believe that's where most of the difference lies.

Politicians are always realistically manoeuvering for the next election. They are obsolete as fundamental problem-solvers.
Buckminster Fuller

ledtech320-Dec-13 15:13

ledtech3

20-Dec-13 15:13

Could the difference be a extra file system filter driver slowing one down ?