Android Question equality and inequality operators with b4a long type

Star-Dust

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• Nov 14, 2017

• #2

Simple, buy a new device, I've tried your code on an old Android 4.0 and it works perfectly

** Service (starter) Create **
** Service (starter) Start **
** Activity (main) Create, isFirst = true **
along is equal to itself
along2 is equal to itself
** Activity (main) Resume **
** Activity (main) Pause, UserClosed = false **

Click to expand...

 

Last edited: Nov 14, 2017

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stevel05

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• Nov 14, 2017

• #3

I copied and pasted your code into a new project and it gives the expected results.

 

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klaus

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• Nov 14, 2017

• #4

I tried it too, works as expected.

 

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lemonisdead

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• Nov 14, 2017

• #5

Inequality confirmed on Lenovo K6 (Android 7.0) and Equality on K10000 (Android 6). Si it really depends on the device

 

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B

b4xfr

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• Nov 14, 2017

• #6

thank you very much for a so fast answer.
I use a real device and android 7.0 for testing. The problem could be that i use VirtualBox. I will investigate more.

 

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B

b4xfr

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• Nov 14, 2017

• #7

lemonisdead said:

Inequality confirmed on Lenovo K6 (Android 7.0) and Equality on K10000 (Android 6). Si it really depends on the device

Click to expand...

Thank you very much. It help a lot. So apparently the problem is not related with my installation

 

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B

b4xfr

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• Nov 14, 2017

• #8

I have tested the code in release mode. And it work as expected. So the problem appears only in debug mode.

B4X:

Dim along As Long = 40000000000000100
     Dim along2 As Long = 40000000000000000
   
     If (along = along) Then
       ToastMessageShow("along is equal to itself",False)
       Log("along is equal to itself")
     Else
       ToastMessageShow("along is not equal to itself",False)
       Log("along is not equal to itself")
     End If
     
   
     If (along2 = along2) Then
       ToastMessageShow("along2 is equal to itself",False)
       Log("along2 is equal to itself")
     Else
       ToastMessageShow("along2 is not equal to itself", False)
       Log("along2 is not equal to itself")
     End If

 

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JordiCP

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• Nov 14, 2017

• #9

It appears only in rapid debug (not legacy) mode, not in Activity_Create, when comparing local vars (not if they are globally declared), and only if they differ in the latest digits

So it "could seem" as if the comparison block logic was performed not with the numbers themselves but with their string representation, but only taking into account up to a given length?
Just a guess

EDIT:
After doing a "Project Clean" it works ok

 

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B

b4xfr

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• Nov 14, 2017

• #10

@JordiCP. Thank you for these precisions.

JordiCP said:

After doing a "Project Clean" it works ok

Click to expand...

The "project clean" worked for me too! (Why?)

 

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JordiCP

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• Nov 14, 2017

• #11

As a rule of thumb, you can do it (clean project) as a check if you see "strange(r) things"
With legacy debugger it doesn't happen, but it's not as fast as the rapid debugger

 

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b4xfr

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• Nov 14, 2017

• #12

JordiCP said:

With legacy debugger it doesn't happen, but it's not as fast as the rapid debugger

Click to expand...

In fact I have only one debug mode. I don't know how to activate the "legacy debugger".

I will avoid if (a=b) and use preferably if (a-b=0), if (a-b)<>0, it worked before i made a "clean project".

 

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lemonisdead

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• Nov 14, 2017

• #13

Tools \ IDE Options \ Use legacy debugger

 

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DonManfred

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• Nov 14, 2017

• #14

You can find the legacy (Deprecated) Debugger in the Menu

 

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B

b4xfr

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• Nov 14, 2017

• #15

Ha, thank you very much, here is the legacy debugger .

 

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Erel

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• Nov 14, 2017

• #16

There is indeed a bug here. It happens in some cases in rapid debug mode (default debugger).

The rapid debugger has two pipelines. One is fast and static and the other is slower and more dynamic / sophisticated. This is why it can be tricky to reproduce it.

It can be reproduced with:

B4X:

Dim along As Long = 40000000000000100
Log(along = along)
Log("put breakpoint here")

I guess that it is related to a conversion between double to long.

I recommend you to keep using the rapid debugger. You can put this code in a different sub. It will run properly as long as you don't modify the code. Clean the project if you do modify it to force a full compilation.

 

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B

b4xfr

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• Nov 14, 2017

• #17

Ok.
Thank you very much. Indeed i can see that with the break point there is a latency before a log appear (with a false result) in the console.

The following code works well. In my point of view, this code will acces the value of the long and compute a difference, and my ancient code behaves as if it tested two different objects. A long versus a Long.

B4X:

Dim along As Long = 40000000000000100
   Log(along - along = 0)
   Log("put breakpoint here")

 

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