Tim_Mac <mackey.tim@gmail.com> wrote:
> in c# i can run the following code without risk of
> NullReferenceException:
>
> if(textNode != null && !String.IsNullOrEmptytextNode.InnerText))
>
> the reason it is safe to run is because if the first condition is
> false, then the CLR will not bother to examine further conditions
> (false and anything else is still false...) and the second part of the
> condition will not evaluate.
>
> however, in VB, i am running the following code:
>
> If Not textNode Is Nothing And Not
> String.IsNullOrEmpty(textNode.InnerText) Then ...
>
> and i get a NullReferenceException... what gives?
> thanks for any tips.

"Tim_Mac" <mackey.tim@gmail.com> wrote in message
news:1146001398.912336.303040@v46g2000cwv.googlegroups.com...
> hi jon,
> that must be it. many thanks for adding this new word to my vb
> vocabulary. it makes you wonder what the normal AND is supposed to do
> then...
> AndNotAlsoButOnlyIfTheFirstOneIsNotFalse.
>
> i'm sure the docs have a perfectly logical answer. no need to explain.
>
> thanks again
> tim
>

Scott M. <s-mar@nospam.nospam> wrote:
> "And" evaluates both sides of the conditional regardless of the first
> conditional actual value. Same is true for "Or". This is for situations
> when the second conditional is a method call and you want the method to run
> regardless of its return value.
>
> "AndAlso" and "OrElse" were added to solve that issue.

"Jon Skeet [C# MVP]" <skeet@pobox.com> wrote in message
news:MPG.1eb90f7130c8001098d158@msnews.microsoft.com...
> Scott M. <s-mar@nospam.nospam> wrote:
>> "And" evaluates both sides of the conditional regardless of the first
>> conditional actual value. Same is true for "Or". This is for situations
>> when the second conditional is a method call and you want the method to
>> run
>> regardless of its return value.
>>
>> "AndAlso" and "OrElse" were added to solve that issue.
>
> I would guess it's historical - because And and Or historically didn't
> do short-circuiting, the behaviour wasn't changed for VB.NET. I doubt
> that many people really *want* the non-short-circuiting behaviour to be
> the more common one...
>
> --
> Jon Skeet - <skeet@pobox.com>
> http://www.pobox.com/~skeet Blog: http://www.msmvps.com/jon.skeet
> If replying to the group, please do not mail me too

"Greg Young [MVP]" <DruckDruckGoose@hotmail.com> wrote in message
news:%2385ghOPaGHA.1196@TK2MSFTNGP03.phx.gbl...
>I agree with this completely .. I remember the first time I came accross
>this years ago having not come a VB background I found it to be the oddest
>thing.
>
> The "interesting" things we bring forward for the sake of "backwards
> thought" compatibility :)
>
>
> "Jon Skeet [C# MVP]" <skeet@pobox.com> wrote in message
> news:MPG.1eb90f7130c8001098d158@msnews.microsoft.com...
>> Scott M. <s-mar@nospam.nospam> wrote:
>>> "And" evaluates both sides of the conditional regardless of the first
>>> conditional actual value. Same is true for "Or". This is for
>>> situations
>>> when the second conditional is a method call and you want the method to
>>> run
>>> regardless of its return value.
>>>
>>> "AndAlso" and "OrElse" were added to solve that issue.
>>
>> I would guess it's historical - because And and Or historically didn't
>> do short-circuiting, the behaviour wasn't changed for VB.NET. I doubt
>> that many people really *want* the non-short-circuiting behaviour to be
>> the more common one...
>>
>> --
>> Jon Skeet - <skeet@pobox.com>
>> http://www.pobox.com/~skeet Blog: http://www.msmvps.com/jon.skeet
>> If replying to the group, please do not mail me too
>
>

"Jon Skeet [C# MVP]" <skeet@pobox.com> wrote in message
news:MPG.1eb86c5bf97577b098d14f@msnews.microsoft.com...
> Tim_Mac <mackey.tim@gmail.com> wrote:
>> in c# i can run the following code without risk of
>> NullReferenceException:
>>
>> if(textNode != null && !String.IsNullOrEmptytextNode.InnerText))
>>
>> the reason it is safe to run is because if the first condition is
>> false, then the CLR will not bother to examine further conditions
>> (false and anything else is still false...) and the second part of the
>> condition will not evaluate.
>>
>> however, in VB, i am running the following code:
>>
>> If Not textNode Is Nothing And Not
>> String.IsNullOrEmpty(textNode.InnerText) Then ...
>>
>> and i get a NullReferenceException... what gives?
>> thanks for any tips.
>
> I believe you want the AndAlso operator. The equivalent for "or" is
> OrElse.

>
> --
> Jon Skeet - <skeet@pobox.com>
> http://www.pobox.com/~skeet Blog: http://www.msmvps.com/jon.skeet
> If replying to the group, please do not mail me too