Complex if statement.

[Arne Garvander]

Exception innerEx;
HttpException checkException ;
checkException = (HttpException)appException;
innerEx = checkException.InnerException;
if (innerEx != null && innerEx.GetType() == typeof(ViewStateException))
{
ErrNotify.LogError(msg, Request.Path, ErrorLevel.ErrorWarning);
}

Will the second part of my if statement execute when innerEx is null? Is
there a way to it prevent from executing?
--
Arne Garvander
(I program VB.Net for fun and C# to get paid.)

[Nicholas Paldino [.NET/C# MVP]]

Arne,

No, in C#, logical expressions short circuit themselves if it can not
effect the result.

So, in this case, if the first part (innerEx != null) is false, since
you are using a logical and, it will not execute "innerEx.GetType() ==
typeof(ViewStateException)"

With a logical or statement, if the first part evaluates to true, then
the second part will not be evaluated.

Hope this helps.
--
- Nicholas Paldino [.NET/C# MVP]
- mv*@spam.guard.caspershouse.com

"Arne Garvander" <Ar***********@discussions.microsoft.com> wrote in message
news:B1**********************************@microsof t.com...

Exception innerEx;
HttpException checkException ;
checkException = (HttpException)appException;
innerEx = checkException.InnerException;
if (innerEx != null && innerEx.GetType() == typeof(ViewStateException))
{
ErrNotify.LogError(msg, Request.Path, ErrorLevel.ErrorWarning);
}

Will the second part of my if statement execute when innerEx is null? Is
there a way to it prevent from executing?
--
Arne Garvander
(I program VB.Net for fun and C# to get paid.)

[Mehdi]

On Tue, 30 May 2006 13:51:02 -0700, Arne Garvander wrote:

Exception innerEx;
HttpException checkException ;
checkException = (HttpException)appException;
innerEx = checkException.InnerException;
if (innerEx != null && innerEx.GetType() == typeof(ViewStateException))
{
ErrNotify.LogError(msg, Request.Path, ErrorLevel.ErrorWarning);
}

Will the second part of my if statement execute when innerEx is null? Is
there a way to it prevent from executing?

No. If the first part of the boolean expression results to false it will
stop there and not even try to evaluate the second part since there would
be no point. But you can see by yourself anyway. That behaviour must be
documented somewhere on MSDN but i can't find where.

[Eddie]

Mehdi wrote:

On Tue, 30 May 2006 13:51:02 -0700, Arne Garvander wrote:

Exception innerEx;
HttpException checkException ;
checkException = (HttpException)appException;
innerEx = checkException.InnerException;
if (innerEx != null && innerEx.GetType() == typeof(ViewStateException))
{
ErrNotify.LogError(msg, Request.Path, ErrorLevel.ErrorWarning);
}

Will the second part of my if statement execute when innerEx is null? Is
there a way to it prevent from executing?

No. If the first part of the boolean expression results to false it will
stop there and not even try to evaluate the second part since there would
be no point. But you can see by yourself anyway. That behaviour must be
documented somewhere on MSDN but i can't find where.

It's documented under Conditional Logical Operators.
See Hejlsberg "The C# Programming Language" (ISBN 0321154916, p218) and
online search (F1) on && Operator in Visual C# Express 2005.

Eddie

[Bruce Wood]

If you use the && operator then it will not evaluate the right-hand
side if the left-hand side is false.

If you use the & operator then it will evaluate both sides regardless
of the value of the left-hand side.

[Mike Schilling]

"Nicholas Paldino [.NET/C# MVP]" <mv*@spam.guard.caspershouse.com> wrote in
message news:uf**************@TK2MSFTNGP02.phx.gbl...

Arne,

No, in C#, logical expressions short circuit themselves if it can not
effect the result.

To be precise, the operators && and || short-circuit. The operators & and
|, which can also be used in logical expressions [1], do not.

1. Note that this is different from C, C++, and Java, in which & and | are
bitwise operators only.

[Jon Skeet [C# MVP]]

Mike Schilling <[e-mail]> wrote:

"Nicholas Paldino [.NET/C# MVP]" <mv*@spam.guard.caspershouse.com> wrote in
message news:uf**************@TK2MSFTNGP02.phx.gbl...

Arne,

No, in C#, logical expressions short circuit themselves if it can not
effect the result.

To be precise, the operators && and || short-circuit. The operators & and
|, which can also be used in logical expressions [1], do not.

1. Note that this is different from C, C++, and Java, in which & and | are
bitwise operators only.

Not sure where you get that idea about Java from:

public class Test
{
public static void main(String[] args)
{
boolean a = true;
boolean b = false;

System.out.println (a&b);
}
}

--
Jon Skeet - <sk***@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

[Mike Schilling]

"Jon Skeet [C# MVP]" <sk***@pobox.com> wrote in message
news:MP************************@msnews.microsoft.c om...

Mike Schilling <[e-mail]> wrote:

"Nicholas Paldino [.NET/C# MVP]" <mv*@spam.guard.caspershouse.com> wrote
in
message news:uf**************@TK2MSFTNGP02.phx.gbl...

> Arne,
>
> No, in C#, logical expressions short circuit themselves if it can
> not
> effect the result.

To be precise, the operators && and || short-circuit. The operators &
and
|, which can also be used in logical expressions [1], do not.

1. Note that this is different from C, C++, and Java, in which & and |
are
bitwise operators only.

Not sure where you get that idea about Java from:

public class Test
{
public static void main(String[] args)
{
boolean a = true;
boolean b = false;

System.out.println (a&b);
}
}

I'll be damned. I stand correct:ed: boolean & and | are exactly the same in
Java as in C#. But in all the hundreds of thousands of lines of Java I've
read through, I don't recall ever seeing them used.

[Jon Skeet [C# MVP]]

Mike Schilling <[e-mail]> wrote:

<snip>

I'll be damned. I stand correct:ed: boolean & and | are exactly the same in
Java as in C#. But in all the hundreds of thousands of lines of Java I've
read through, I don't recall ever seeing them used.

Likewise - but that's true in C# for me as well :)

--
Jon Skeet - <sk***@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

[james.curran]

Funny, I'm sure I posted this yesterday, but it seems to have slipped
into the ether...

The second part of the if() statement can be written as:
if (innerEx != null && innerEx is ViewStateException)

With the proviso that your method would be true if innerEx is
specifically a ViewStateException, while using "is" would be true if it
is a ViewStateException or any class derived from ViewStateException.

Further, "is" is safe for nulls, so the entire if() can be written as:
if (innerEx is ViewStateException)

which, while not answering your question, neatly avoids it.

Arne Garvander wrote:

Exception innerEx;
HttpException checkException ;
checkException = (HttpException)appException;
innerEx = checkException.InnerException;
if (innerEx != null && innerEx.GetType() == typeof(ViewStateException))
{
ErrNotify.LogError(msg, Request.Path, ErrorLevel.ErrorWarning);
}