Re: Why not True - C# Discussion Boards

Henry Minute4-Feb-09 5:17

4-Feb-09 5:17

I am coding an override for OnDragDrop, only DataFormat.FileDrop is valid, tested for in OnDragEnter and in the OnDragDrop handler.

I've just reviewed the code and noticed that I have put in a if (File.Exists(filename)) test before allowing the drop.
Is this test redundant? I mean, are there any circumstances in which a DataFormats.FileDrop can occur apart from when dragging from explorer, or other shell source.

This must be a really daft question but my brain is going in circles at the moment and I can't get my head round it.

Henry Minute

Do not read medical books! You could die of a misprint. - Mark Twain
Girl: (staring) "Why do you need an icy cucumber?"
“I want to report a fraud. The government is lying to us all.”

Re: Simple DragDrop question

led mike4-Feb-09 6:04

led mike

4-Feb-09 6:04

Henry Minute wrote:
are there any circumstances in which a DataFormats.FileDrop can occur apart from when dragging from explorer, or other shell source.

I've never tried it, but I suspect any application can create a FileDrop event. Furthermore I suspect it is possible to do it such that your test would evaluate to false.

Re: Simple DragDrop question

Henry Minute4-Feb-09 6:11

Henry Minute

4-Feb-09 6:11

Cheers.
I'll leave it as is, I think, unless I hear otherwise from the C# sages.

Re: Simple DragDrop question

Luc Pattyn4-Feb-09 6:38

Luc Pattyn

4-Feb-09 6:38

Hi Henry,

one can programmatically drop just about anything on an app, including non-existing files.
Also files can get deleted while a drag-drop is going on.

On the other hand, when a file gets operated on (as in after the drop), you need to have
error handling anyway, so you may as well skip the test.

Smile | :)

Luc Pattyn [Forum Guidelines] [My Articles]

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Re: Simple DragDrop question

Henry Minute4-Feb-09 8:46

Henry Minute

4-Feb-09 8:46

Luc Pattyn wrote:
when a file gets operated on (as in after the drop), you need to have
error handling anyway

Good thinking Batman!

Why not True

ziwez04-Feb-09 4:53

ziwez0

4-Feb-09 4:53

// StatusID =2
// xGetStatusOID = 2
if (StatusID.CompareTo(xGetStatusOID).Equals(true))
{
ii = 1;
}
else
{
ii = 2;
}

//Result
//ii = 2

Re: Why not True

SeMartens4-Feb-09 5:00

SeMartens

4-Feb-09 5:00

well, CompareTo returns an int, saying whether the passed argument is less, equals or greater than the object.

You can rewrite your code like this:

ii = (StatusID.Equals(xGetStatusOID) ? 1 : 2);

That's all.

Regards
Sebastian

It's not a bug, it's a feature!

Check out my CodeProject article Permission-by-aspect.

Me in Softwareland.

Re: Why not True

Luc Pattyn4-Feb-09 5:01

Luc Pattyn

4-Feb-09 5:01

Hi,

what are you doing?
did you check the return type of CompareTo?
does your code even compile?
why not simply if(StatusID==xGetStatusOID) { ... } else { ... }?

I recommend you buy a book on the language or technology of interest and study it.

Smile | :)

Luc Pattyn [Forum Guidelines] [My Articles]

Re: Why not True

ziwez04-Feb-09 5:23

ziwez0

4-Feb-09 5:23

This code does compile and returns false,
perhaps you should of read what I wrote, it was a question.

Re: Why not True

J4amieC4-Feb-09 5:34

J4amieC

4-Feb-09 5:34

ziwez0 wrote:
perhaps you should of read what I wrote, it was a question.

No you didnt, you just posted some code!

Perhaps you should buy a beginner book on C# and work your way through it!

Re: Why not True

ziwez04-Feb-09 6:16

ziwez0

4-Feb-09 6:16

Hi j4amieC,

J4amieC wrote:
No you didnt, you just posted some code!

Suject "Why not True"
http://www.thefreedictionary.com/why[^]

I asked a question?, perhaps if you spent more time reading what people write, maybe your reponse might be helpful (like Alan's post), instead of your alternative which was a quick dismissal of someone's question.

Re: Why not True [modified]

Luc Pattyn4-Feb-09 5:36

Luc Pattyn

4-Feb-09 5:36

Hi,

yes you are absolutely right, it does compile (well, after one adds type declarations for all the variables used), although it does not make sense whatsoever.

CompareTo returns an int
int.Equals(true) returns false no matter what.

It may help to read some documentation[^] especially if you insist on using methods you don't really need and apparently don't understand well.

Smile | :)

Luc Pattyn [Forum Guidelines] [My Articles]

modified on Friday, June 10, 2011 11:35 AM

Re: Why not True

PIEBALDconsult4-Feb-09 5:21

PIEBALDconsult

4-Feb-09 5:21

Why use methods when operators will suffice?

Re: Why not True

musefan4-Feb-09 5:36

musefan

4-Feb-09 5:36

is it because :

bool == 0; is false?

you are comparing an 'integer' to a 'bool' which is always false as they are different types

My opinion is... If someone has already posted an answer, dont post the SAME answer

Re: Why not True [modified]

Alan N4-Feb-09 5:40

Alan N

4-Feb-09 5:40

Ok
Lets break your code into steps

int result1 = StatusID.CompareTo(xGetStatusOID);
// result1 will be zero as the values are equal
bool result2 = result1.Equals(true);
//result2 will be false

The overload of Equals your code would call is

public override bool Equals (Object obj)

and the documentation says

The return value is true if obj is an instance of Int32 and equals the value of this instance; otherwise, false.

Alan.

modified on Wednesday, February 4, 2009 12:01 PM

Re: Why not True

ziwez04-Feb-09 6:24

ziwez0

4-Feb-09 6:24

Thanks Alan,

I also looked at http://msdn.microsoft.com/en-us/library/fbh501kz(VS.80).aspx[^]

I Was expecting it to return 1, but yes your right it will return 0

Re: Why not True [modified]

Luc Pattyn4-Feb-09 6:43

Luc Pattyn

4-Feb-09 6:43

The page you provided a link to discusses string comparison.
How does that relate to the original question?

Further more whether CompareTo returns 0, 1 or any other number is irrelevant as long as
you apply .Equals(true) to it, since that will ALWAYS return false.

Luc Pattyn [Forum Guidelines] [My Articles]

modified on Friday, June 10, 2011 11:35 AM

Re: Why not True

ziwez04-Feb-09 7:03

ziwez0

4-Feb-09 7:03

Hi Luc,

Yes the link was a string comparision, but dont forget that Int32 Supports the CompareToMethod,
and they both return 0 if "strA equals strB."
And as mentioned I thought it would return 1 and not 0.

Re: Why not True [modified]

Luc Pattyn4-Feb-09 7:16

Luc Pattyn

4-Feb-09 7:16

You read the wrong pages, you think you read the opposite of what they say,
you ignore earlier good advice, in short you don't have a clue.
I suggest a career change.

Smile | :)

Luc Pattyn [Forum Guidelines] [My Articles]

modified on Friday, June 10, 2011 11:35 AM

Re: Why not True

ziwez04-Feb-09 7:33

ziwez0

4-Feb-09 7:33

Thanks for that, keep up the good advice.... Laugh | :laugh:

Re: Why not True

User 66584-Feb-09 8:46

User 6658

4-Feb-09 8:46

You still don't understand that comparing 1 to true would still return false anyway. So it is irrelevant whether CompareTo would return 0, 1 or PI, the result would always be false in your case.

modified 12-Sep-18 21:01pm.

Re: Why not True

ziwez05-Feb-09 2:03

ziwez0

5-Feb-09 2:03

Hi Greeeg,

thanks for taking the time to post, yeah your right, I was just expecting it to return 1 (true),
I was just curious, but after alans post made me look on MSDN, so it would be more like
if (i.CompareTo(ii).Equals(0)) ((0\1)and not true\false)

thanks tho.

adjust my machine's utc?

mirko864-Feb-09 4:40

mirko86

4-Feb-09 4:40

good morning people, can someone tell me how can i adjust a pc's UTC by code?

Re: adjust my machine's utc?

PIEBALDconsult4-Feb-09 5:22

PIEBALDconsult

4-Feb-09 5:22