Need an expression to check whether an object is null in the debugger

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Casey - 23 Sep 2003 21:05 GMT

In VS .NET (2002), how can you check whether an object is null in the
debugger (Watch window)?

The following expression evaluates correctly...

myString == string.Empty

...however, this expression produces "error: unable to evaluate expression"

myString == null

Any ideas why? Is there another way to check whether an object is null?

Thanks,
Casey

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Me - 29 Sep 2003 14:33 GMT

Does it produce that error regardless of whether myString actually is null?
If not, you have your answer. BTW string being empty, i.e., "", is different
from null.

Signature

Jim
"Remember, an amateur built the Ark; professionals built the Titanic."

> In VS .NET (2002), how can you check whether an object is null in the
> debugger (Watch window)?
[quoted text clipped - 11 lines]
> Thanks,
> Casey

Reply to this Message

Casey - 29 Oct 2003 23:56 GMT

I want to set a breakpoint that conditionally breaks if an object is null.
However, I have not been able to find any syntax that allows me to do this.
When I try to compare the object to null, VS .NET says it is invalid syntax.

> Does it produce that error regardless of whether myString actually is null?
> If not, you have your answer. BTW string being empty, i.e., "", is different
[quoted text clipped - 19 lines]
> > Thanks,
> > Casey

Reply to this Message

Nick Savoiu - 30 Oct 2003 02:09 GMT

Did you try comparing with 0?

Nick

> I want to set a breakpoint that conditionally breaks if an object is null.
> However, I have not been able to find any syntax that allows me to do this.
[quoted text clipped - 25 lines]
> > > Thanks,
> > > Casey

Reply to this Message

Casey - 05 Nov 2003 22:40 GMT

Yes, I did. It evaluates to false regardless of whether it is null or not.

> Did you try comparing with 0?
>
[quoted text clipped - 32 lines]
> > > > Thanks,
> > > > Casey

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Nick Savoiu - 06 Nov 2003 00:12 GMT

that doesn't sound right... what was the condition that you were breaking
on?

nick

> Yes, I did. It evaluates to false regardless of whether it is null or not.
>
[quoted text clipped - 36 lines]
> > > > > Thanks,
> > > > > Casey

Reply to this Message

Casey - 07 Nov 2003 23:08 GMT

I have code like this...

object o = null;
int i = 3; // set a breakpoint here
int j = 5; // want to set a conditional breakpoint here; only want to break
here if o is null

In the visual studio .NET watch window, type the expression "o == 0". It
evaluates to false even though o is null. If I just watch the object o, the
watch window says it is null. However, I can't find an expression that will
allow me to compare an object vs null, therefore I can't conditionally break
if the object is null.

> that doesn't sound right... what was the condition that you were breaking
> on?
[quoted text clipped - 44 lines]
> > > > > > Thanks,
> > > > > > Casey

Reply to this Message

Need an expression to check whether an object is null in the debugger

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