A question about exceptions

[=?Utf-8?B?RWR3YXJk?=]

Hi everybody,
I was testing a piece of code and I noticed that try catch block doesn't
recognize "DivideByZeroEx ception" when I have zero in denominator and I have
to use the "OverflowExcept ion" , I can't figure out why VB behaves this way ,
Any thoughts?
--
Best regards,
Edward

[Tom Shelton]

On 2008-05-30, Edward <Ed****@discuss ions.microsoft. comwrote:

Hi everybody,
I was testing a piece of code and I noticed that try catch block doesn't
recognize "DivideByZeroEx ception" when I have zero in denominator and I have
to use the "OverflowExcept ion" , I can't figure out why VB behaves this way ,
Any thoughts?

You probably need to read the documentation on the DivideByZeroExc eption
:) See, this one is only thrown by integer and decimal types. Floating
point numbers, single and double do not throw this exception - they
return NaN.

Now, you are probably going to say that you are using integers - but,
probably not... See VB (both classic and .NET) have two division
operators / and \. The commonly used / actually performs it's work by
converting it's operands to double values - so it won't throw this
exception. I would bet that if you switched to \ instead - doing
integer division that it would throw a DivideByZeroExc eption... Here
let me try it real quick :)

Yep... In fact, if you do say 3\0 using literals - it won't even
compile :) But if you do it with variables, then a
DivideByZeroExc eption is thrown at runtime.

--
Tom Shelton

[Armin Zingler]

"Edward" <Ed****@discuss ions.microsoft. comschrieb

Hi everybody,
I was testing a piece of code and I noticed that try catch block
doesn't recognize "DivideByZeroEx ception" when I have zero in
denominator and I have to use the "OverflowExcept ion" , I can't
figure out why VB behaves this way , Any thoughts?

Can't repro this. Can you show some code? Do you have Option Strict
enabled? I guess you try to assign the result of a floating point
division to an Integer value. So, not the division is the problem, the
assignment is. We must distinguish between floating point division and
integer division. The former does not throw an exception if the
demoninator is 0. Instead the result is PositiveInfinit y,
NegativeInfinit y or NaN (see help for / operator). The latter throws a
DivideByZeroExc eption.
Armin

[Tom Shelton]

On 2008-05-30, Armin Zingler <az*******@free net.dewrote:

"Edward" <Ed****@discuss ions.microsoft. comschrieb

>Hi everybody,
I was testing a piece of code and I noticed that try catch block
doesn't recognize "DivideByZeroEx ception" when I have zero in
denominator and I have to use the "OverflowExcept ion" , I can't
figure out why VB behaves this way , Any thoughts?

Can't repro this. Can you show some code? Do you have Option Strict
enabled? I guess you try to assign the result of a floating point
division to an Integer value. So, not the division is the problem, the
assignment is. We must distinguish between floating point division and
integer division. The former does not throw an exception if the
demoninator is 0. Instead the result is PositiveInfinit y,
NegativeInfinit y or NaN (see help for / operator). The latter throws a
DivideByZeroExc eption.
Armin

/ converts its operands to floating point values - so does not throw a
DivisionByZeroE xception. You need to be doing integer division (\) to
get that exception.

--
Tom Shelton

[=?Utf-8?B?RWR3YXJk?=]

Both of you guys were right ! I wasn't aware of integer division !
--
Best regards,
Edward
"Tom Shelton" wrote:

On 2008-05-30, Armin Zingler <az*******@free net.dewrote:

"Edward" <Ed****@discuss ions.microsoft. comschrieb

Hi everybody,
I was testing a piece of code and I noticed that try catch block
doesn't recognize "DivideByZeroEx ception" when I have zero in
denominator and I have to use the "OverflowExcept ion" , I can't
figure out why VB behaves this way , Any thoughts?

Can't repro this. Can you show some code? Do you have Option Strict
enabled? I guess you try to assign the result of a floating point
division to an Integer value. So, not the division is the problem, the
assignment is. We must distinguish between floating point division and
integer division. The former does not throw an exception if the
demoninator is 0. Instead the result is PositiveInfinit y,
NegativeInfinit y or NaN (see help for / operator). The latter throws a
DivideByZeroExc eption.
Armin

/ converts its operands to floating point values - so does not throw a
DivisionByZeroE xception. You need to be doing integer division (\) to
get that exception.

--
Tom Shelton

[=?Utf-8?B?S2VycnkgTW9vcm1hbg==?=]

Tom,

I think it depends on the operand types. For example, this function will
throw a DivideByZero exception if donors is zero:

Private Function getAverage(ByVa l donations As Decimal, ByVal donors As
Integer) As Decimal

'Calculate and return the average donation
getAverage = donations / donors

End Function

Kerry Moorman
"Tom Shelton" wrote:

>
/ converts its operands to floating point values - so does not throw a
DivisionByZeroE xception. You need to be doing integer division (\) to
get that exception.

--
Tom Shelton

[Armin Zingler]

"Tom Shelton" <to*********@YO UKNOWTHEDRILLco mcast.netschrie b

Can't repro this. Can you show some code? Do you have Option
Strict enabled? I guess you try to assign the result of a floating
point division to an Integer value. So, not the division is the
problem, the assignment is. We must distinguish between floating
point division and integer division. The former does not throw an
exception if the demoninator is 0. Instead the result is
PositiveInfinit y,
NegativeInfinit y or NaN (see help for / operator). The latter
throws a DivideByZeroExc eption.

/ converts its operands to floating point values - so does not throw
a DivisionByZeroE xception. You need to be doing integer division
(\) to get that exception.

Yep, that's what I wrote.
Armin

[Tom Shelton]

On May 30, 4:59*pm, Kerry Moorman
<KerryMoor...@d iscussions.micr osoft.comwrote:

Tom,

I think it depends on the operand types. For example, this function will
throw a DivideByZero exception if donors is zero:

* * Private Function getAverage(ByVa l donations As Decimal, ByVal donors As
Integer) As Decimal

* * * * 'Calculate and return the average donation
* * * * getAverage = donations / donors

* * End Function

Kerry Moorman

Hmm... Actually, that's probably correct in this case. Since
decimals can hold a bigger range of numbers, the / operator probably
does use decimal in this case - and decimal is really an integer type
under the covers, so it throws the DivideByZeroExc eption. Not one I
thought about since, VB.CLASSIC didn't have a real decimal type (it
was a variant sub type)....

Thanks for that, Kerry.

--
Tom Shelton