The Weird and The Wonderful

Manfred Rudolf Bihy16-Dec-13 1:23

Manfred Rudolf Bihy

16-Dec-13 1:23

The compiler should issue a warning or unreachable code. Did it?
And what with the uninitialised statusMutex thingy?
Or is there some background magic going on I'm not privy to?

Cheers!

"I had the right to remain silent, but I didn't have the ability!"

Ron White, Comedian

Marco Bertschi16-Dec-13 3:18

Marco Bertschi

16-Dec-13 3:18

Manfred R. Bihy wrote:
And what with the uninitialised statusMutex thingy?

It is initialized - It is Qt code, where objects can be initialized by just writing "ObjectType variablename;".
Remember that this is a must for constructors not accepting any parameters - Otherwise they'd be mistaken for method calls, leading the compiler to throw up.

And, No - The compiler did not issue a warning or an error, may has something to do with the Qt-Plugin not playing nice to VS 2012.

Veni, vidi, caecus

Manfred Rudolf Bihy16-Dec-13 3:22

Manfred Rudolf Bihy

16-Dec-13 3:22

Marco Bertschi wrote:
It is Qt code, where objects can be initialized by just writing "ObjectType variablename;".

Interesting, to say the least. What would you do in Qt if you wanted an uninitialised variable declaration?

Cheers!

"I had the right to remain silent, but I didn't have the ability!"

Ron White, Comedian

Marco Bertschi16-Dec-13 4:31

Marco Bertschi

16-Dec-13 4:31

Not initialized variables are bad!
Nevertheless, go for MyType myObject = 0;.
Initialize to 0 because the MS C++ compiler may get a little hiccup if you try it with NULL - Even though it is theoretically valid, MS uses another value which is != 0 for the debug versions to avoid the use of unintilized variables - This behavior may lead to system crashes in the debug version, therefore my first statement.

Veni, vidi, caecus

Manfred Rudolf Bihy16-Dec-13 4:35

Manfred Rudolf Bihy

16-Dec-13 4:35

Marco Bertschi wrote:
Not initialized variables are bad!

I'm an engineer, trust me, I know what I'm adfsadfasdfdfffffffffffffffffffffüllächt!

Poke tongue | ;-P

"I had the right to remain silent, but I didn't have the ability!"

Ron White, Comedian

Pablo Aliskevicius16-Dec-13 4:40

Pablo Aliskevicius

16-Dec-13 4:40

Why didn't you use RAII?

C++

class  MutexLocker {
    QMutex &m;
public:
    MutexLocker(QMutex &qm) : m(qm) { m.lock(); }
    ~MutexLocker() { m.unlock(); }
}; // class

int GetStatus(){
   MutexLocker tmp(statusMutex);
   return status;
   // destructor unlocks 
}

Pablo.

"Accident: An inevitable occurrence due to the action of immutable natural laws." (Ambrose Bierce, circa 1899).
"You are to act in the light of experience as guided by intelligence" (Rex Stout, "In the Best Families", 1950).

Albert Holguin28-Dec-13 12:10

Albert Holguin

28-Dec-13 12:10

Manfred R. Bihy wrote:
The compiler should issue a warning or unreachable code. Did it?

Is that what I just ignored... D'Oh! | :doh:

Albert Holguin28-Dec-13 12:08

Albert Holguin

28-Dec-13 12:08

"worst code you'll ever see is the one you wrote last year"

Yes I know it was me who wrote that...

charlieg14-Jan-14 23:17

charlieg

14-Jan-14 23:17

Haha - I have the same t-shirt. I earned it late one night trying to debug a release build problem. Had wrapped important code with #ifdef DEBUG..

Charlie Gilley
<italic>You're going to tell me what I want to know, or I'm going to beat you to death in your own house.

"Where liberty dwells, there is my country." B. Franklin, 1783
“They who can give up essential liberty to obtain a little temporary safety deserve neither liberty nor safety.” BF, 1759

GuyThiebaut10-Dec-13 5:51

GuyThiebaut

10-Dec-13 5:51

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

[Head hangs in shame] D'Oh! | :doh:

I should have coded:

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

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

― Christopher Hitchens

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

OriginalGriff

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

OriginalGriff

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

Argonia

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

OriginalGriff

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