== operator not working on boxed value types

[Kenneth Baltrinic]

I have the following routine that is always throwing the error at the end.
It never returns from within the foreach loop because the if expression is
always evaluating to false apparently. This is something of a problem. The
comparison is between two objects (Handler.Data is defined as returning an
object.), but these objects are always nothing more than boxed value types
(either strings or ints or an int based enumeration). If for the sake of a
particular test where I knew all the values were ints, I recoded the
comparison to look like
if((int)Handler .Data == (int)Value)
and all worked fine. The problem is I can rely on this assumption. Any
suggestions on this issue?

protected virtual void HandleValueChan ge(ref object Value)
{
foreach(PSCForm s.MenuHandler Handler in MenuHandlers)
if(Handler.Data == Value)
{
Handler.MenuIte m.DefaultItem = true;
this.Text = Handler.MenuIte m.Text.Replace( "&", "");
return;
}

throw new ArgumentOutOfRa ngeException(
"Value", Value, "The value is not is the list of acceptable values.");
}

P.S. One more bizarre thing, if I put (Handler.Data == Value) in a watch
window and step through the routine, the window indicates that the
expression evaluates to true for the appropriate iteration, but the code
within the if block still does not run. Could this be a C# bug?

--Ken

[Sherif ElMetainy]

Hello

With the variables of type object, the == performs a reference equality,
which is usually false unless the 2 objects actually reference to the same
object.
You should use the static method Object.Equals(o bject1, object2).

Best regards
Sherif

"Kenneth Baltrinic" <ke*****@baltri nic.com> wrote in message
news:us******** ******@TK2MSFTN GP09.phx.gbl...

I have the following routine that is always throwing the error at the end.
It never returns from within the foreach loop because the if expression is
always evaluating to false apparently. This is something of a problem. The comparison is between two objects (Handler.Data is defined as returning an
object.), but these objects are always nothing more than boxed value types
(either strings or ints or an int based enumeration). If for the sake of a particular test where I knew all the values were ints, I recoded the
comparison to look like
if((int)Handler .Data == (int)Value)
and all worked fine. The problem is I can rely on this assumption. Any
suggestions on this issue?

protected virtual void HandleValueChan ge(ref object Value)
{
foreach(PSCForm s.MenuHandler Handler in MenuHandlers)
if(Handler.Data == Value)
{
Handler.MenuIte m.DefaultItem = true;
this.Text = Handler.MenuIte m.Text.Replace( "&", "");
return;
}

throw new ArgumentOutOfRa ngeException(
"Value", Value, "The value is not is the list of acceptable values.");
}

P.S. One more bizarre thing, if I put (Handler.Data == Value) in a watch
window and step through the routine, the window indicates that the
expression evaluates to true for the appropriate iteration, but the code
within the if block still does not run. Could this be a C# bug?

--Ken

[Kenneth Baltrinic]

I am aware of how the operator works for object variables in general but I
was under the impression it would unbox boxed value types before applying a
operator. This is particularly so since the watch window did in fact return
the value I was expecting. That the watch window and code execution are out
of step is most disturbing.

What about the instance method Equals()? I just tested it and it works as
well. This is unrelated to my issue but why is there both an instance and
static method?

--Ken

"Sherif ElMetainy" <el************ *@wayout.net.NO SPAM> wrote in message
news:e%******** ********@TK2MSF TNGP09.phx.gbl. ..

Hello

With the variables of type object, the == performs a reference equality,
which is usually false unless the 2 objects actually reference to the same
object.
You should use the static method Object.Equals(o bject1, object2).

Best regards
Sherif

"Kenneth Baltrinic" <ke*****@baltri nic.com> wrote in message
news:us******** ******@TK2MSFTN GP09.phx.gbl...

I have the following routine that is always throwing the error at the end. It never returns from within the foreach loop because the if expression is always evaluating to false apparently. This is something of a problem. The

comparison is between two objects (Handler.Data is defined as returning an object.), but these objects are always nothing more than boxed value types (either strings or ints or an int based enumeration). If for the sake of a

particular test where I knew all the values were ints, I recoded the
comparison to look like
if((int)Handler .Data == (int)Value)
and all worked fine. The problem is I can rely on this assumption. Any
suggestions on this issue?

protected virtual void HandleValueChan ge(ref object Value)
{
foreach(PSCForm s.MenuHandler Handler in MenuHandlers)
if(Handler.Data == Value)
{
Handler.MenuIte m.DefaultItem = true;
this.Text = Handler.MenuIte m.Text.Replace( "&", "");
return;
}

throw new ArgumentOutOfRa ngeException(
"Value", Value, "The value is not is the list of acceptable

values."); }

P.S. One more bizarre thing, if I put (Handler.Data == Value) in a watch
window and step through the routine, the window indicates that the
expression evaluates to true for the appropriate iteration, but the code
within the if block still does not run. Could this be a C# bug?

--Ken

[Jon Skeet [C# MVP]]

Kenneth Baltrinic <ke*****@baltri nic.com> wrote:

I have the following routine that is always throwing the error at the end.
<snip>
protected virtual void HandleValueChan ge(ref object Value)
Sherif has answered your main question, but I'm concerned with your use
of "ref" here - you're not changing the value of the "Value" variable,
which means that it being passed by reference is irrelevant. Is there
more code in the real method which makes it worth doing this?

See http://www.pobox.com/~skeet/csharp/parameters.html for more
information.
P.S. One more bizarre thing, if I put (Handler.Data == Value) in a watch
window and step through the routine, the window indicates that the
expression evaluates to true for the appropriate iteration, but the code
within the if block still does not run. Could this be a C# bug?

I rather suspect that the watch window uses slightly different
techniques to evaluate things, unfortunately.

--
Jon Skeet - <sk***@pobox.co m>
http://www.pobox.com/~skeet
If replying to the group, please do not mail me too

[Jon Skeet [C# MVP]]

Kenneth Baltrinic <ke*****@baltri nic.com> wrote:

I am aware of how the operator works for object variables in general but I
was under the impression it would unbox boxed value types before applying a
operator.
Why would it do that? It would have to check whether or not the
reference type was a boxed value, and make that check *every* time it
did a reference comparison. That would make it *much* slower, IMO.
What about the instance method Equals()? I just tested it and it works as
well. This is unrelated to my issue but why is there both an instance and
static method?

The static method is more convenient if the references in question
could both be null.

--
Jon Skeet - <sk***@pobox.co m>
http://www.pobox.com/~skeet
If replying to the group, please do not mail me too

[Sherif ElMetainy]

Hello

The instance version of Equals is fine, but object1.Equals( object2) will
throw a NullReferenceEx ception if object1 is null. So if you know that
object1 should never be null then instance version is fine ( and even
better). The static version check for if the value is null, and actually
calls the instance version.

Best regards,
Sherif

"Kenneth Baltrinic" <ke*****@baltri nic.com> wrote in message
news:OE******** ******@TK2MSFTN GP09.phx.gbl...

I am aware of how the operator works for object variables in general but I
was under the impression it would unbox boxed value types before applying a operator. This is particularly so since the watch window did in fact return the value I was expecting. That the watch window and code execution are out of step is most disturbing.

What about the instance method Equals()? I just tested it and it works as
well. This is unrelated to my issue but why is there both an instance and
static method?

--Ken

"Sherif ElMetainy" <el************ *@wayout.net.NO SPAM> wrote in message
news:e%******** ********@TK2MSF TNGP09.phx.gbl. ..

Hello

With the variables of type object, the == performs a reference equality,
which is usually false unless the 2 objects actually reference to the same

object.
You should use the static method Object.Equals(o bject1, object2).

Best regards
Sherif

"Kenneth Baltrinic" <ke*****@baltri nic.com> wrote in message
news:us******** ******@TK2MSFTN GP09.phx.gbl...

I have the following routine that is always throwing the error at the end. It never returns from within the foreach loop because the if expression

is

always evaluating to false apparently. This is something of a

problem. The

comparison is between two objects (Handler.Data is defined as

returning an object.), but these objects are always nothing more than boxed value types (either strings or ints or an int based enumeration). If for the sake

of

a

particular test where I knew all the values were ints, I recoded the
comparison to look like
if((int)Handler .Data == (int)Value)
and all worked fine. The problem is I can rely on this assumption.

Any suggestions on this issue?

protected virtual void HandleValueChan ge(ref object Value)
{
foreach(PSCForm s.MenuHandler Handler in MenuHandlers)
if(Handler.Data == Value)
{
Handler.MenuIte m.DefaultItem = true;
this.Text = Handler.MenuIte m.Text.Replace( "&", "");
return;
}

throw new ArgumentOutOfRa ngeException(
"Value", Value, "The value is not is the list of acceptable

values."); }

P.S. One more bizarre thing, if I put (Handler.Data == Value) in a watch window and step through the routine, the window indicates that the
expression evaluates to true for the appropriate iteration, but the code within the if block still does not run. Could this be a C# bug?

--Ken

[Kenneth Baltrinic]

Good point about the null exception. Its a non issue in this case. And I
do see the point about why it does not unbox. For some reason I was
thinking that the decision to unbox could be made at compile time. Duh.
Fuzzy thinking yesterday.

Regarding the person who queried about the use of the ref modifier, this is
a protected implementation. Overriding implementations may need to modify
the value though this one does not.

Again thanks for al the help.

--Ken
"Kenneth Baltrinic" <ke*****@baltri nic.com> wrote in message
news:us******** ********@TK2MSF TNGP09.phx.gbl. ..

I have the following routine that is always throwing the error at the end.
It never returns from within the foreach loop because the if expression is
always evaluating to false apparently. This is something of a problem. The comparison is between two objects (Handler.Data is defined as returning an
object.), but these objects are always nothing more than boxed value types
(either strings or ints or an int based enumeration). If for the sake of a particular test where I knew all the values were ints, I recoded the
comparison to look like
if((int)Handler .Data == (int)Value)
and all worked fine. The problem is I can rely on this assumption. Any
suggestions on this issue?

protected virtual void HandleValueChan ge(ref object Value)
{
foreach(PSCForm s.MenuHandler Handler in MenuHandlers)
if(Handler.Data == Value)
{
Handler.MenuIte m.DefaultItem = true;
this.Text = Handler.MenuIte m.Text.Replace( "&", "");
return;
}

throw new ArgumentOutOfRa ngeException(
"Value", Value, "The value is not is the list of acceptable values.");
}

P.S. One more bizarre thing, if I put (Handler.Data == Value) in a watch
window and step through the routine, the window indicates that the
expression evaluates to true for the appropriate iteration, but the code
within the if block still does not run. Could this be a C# bug?

--Ken