compiler/debugger misinterpreting variable data in IF

[VMI]

I have a really simple IF statement that looks like this:

if (sNewString.Len gth == iCount)
{
MessageBox.Show (sNewString.Len gth.ToString() + " is equal to " +
iCount.ToString () + "*" + sNewString + "*");
}
if (sNewString.Tri m() == "")
{
MessageBox.Show ("");
}
if (sNewString.Len gth == 0)
{
MessageBox.Show ("Length equals 0");
}
if (sNewString == null)
{
MessageBox.Show ("NULL");
}
if (sNewString.Len gth<iCount)
{
MessageBox.Show ("sNewString.Le ngth<iCount");
}
if (sNewString.Len gth>iCount)
{
MessageBox.Show ("sNewString.Le ngth>iCount");
}

When the debugger reaches the first IF, the debugger shows that
sNewString.Leng th = 0, iCount = 1, and sNewString = "". The frustrating
thing is that it only enters the first IF ("sNewString.Le ngth == iCount")
and the MessageBox displays "1 is equal to 1*" at exactly the same time the
debugger's showing that sNewString.Leng th = 0 and iCount = 1. How can this
be possible? The messagebox and the debugger are showing different
information. I did notice that the MessageBox didn't display the last '*'
(anything after this instance of sNewString is truncated) but I have another
IF statement that checks for NULL but it never enters that IF.
The only thing I can think of is that, before these comparisons, I convert
this specific char into a string (the byte value of this specific char is
equal to 0) so I can do the IF comparisons. But that's it.

Any information is really appreciated.

[Ken Kolda]

I think you answered your own question:

The only thing I can think of is that, before these comparisons, I convert
this specific char into a string (the byte value of this specific char is
equal to 0) so I can do the IF comparisons. But that's it.
Your string almost certainly contains 1 character, which has ASCII value 0.
But ASCII 0 isn't a printable character, so when you look at the string
contents, you see "". Also, when you show it in the message box, the message
box interprets the character as the end of the string, which is why you
don't see the final "*".

All that said, I don't under stand why you're converting the character to a
string. Your reasoning was so that you could do the IF conparisons, but you
can use chars in IFs so I'm not sure what you mean.

Ken
"VMI" <vo******@yahoo .com> wrote in message
news:%2******** ********@TK2MSF TNGP09.phx.gbl. .. I have a really simple IF statement that looks like this:

if (sNewString.Len gth == iCount)
{
MessageBox.Show (sNewString.Len gth.ToString() + " is equal to " +
iCount.ToString () + "*" + sNewString + "*");
}
if (sNewString.Tri m() == "")
{
MessageBox.Show ("");
}
if (sNewString.Len gth == 0)
{
MessageBox.Show ("Length equals 0");
}
if (sNewString == null)
{
MessageBox.Show ("NULL");
}
if (sNewString.Len gth<iCount)
{
MessageBox.Show ("sNewString.Le ngth<iCount");
}
if (sNewString.Len gth>iCount)
{
MessageBox.Show ("sNewString.Le ngth>iCount");
}

When the debugger reaches the first IF, the debugger shows that
sNewString.Leng th = 0, iCount = 1, and sNewString = "". The frustrating
thing is that it only enters the first IF ("sNewString.Le ngth == iCount")
and the MessageBox displays "1 is equal to 1*" at exactly the same time the debugger's showing that sNewString.Leng th = 0 and iCount = 1. How can this
be possible? The messagebox and the debugger are showing different
information. I did notice that the MessageBox didn't display the last '*'
(anything after this instance of sNewString is truncated) but I have another IF statement that checks for NULL but it never enters that IF.
The only thing I can think of is that, before these comparisons, I convert
this specific char into a string (the byte value of this specific char is
equal to 0) so I can do the IF comparisons. But that's it.

Any information is really appreciated.

[VMI]

I imagined that could've been it.
These IF statements are in another method that receive a string as
parameter. Most of the times this method is called with a string, but in
certain cases, I need to pass this char as parameter. So I convert the char
to string, and then call the method.
Once I convert this char to string, how can I distinguish between a null
string, an empty string, and this string?

Thanks again.

Ken Kolda <ke*******@elli emae-nospamplease.co m> wrote in message
news:#Y******** *****@tk2msftng p13.phx.gbl...

I think you answered your own question:

The only thing I can think of is that, before these comparisons, I convert this specific char into a string (the byte value of this specific char is equal to 0) so I can do the IF comparisons. But that's it.
Your string almost certainly contains 1 character, which has ASCII value

0. But ASCII 0 isn't a printable character, so when you look at the string
contents, you see "". Also, when you show it in the message box, the message box interprets the character as the end of the string, which is why you
don't see the final "*".

All that said, I don't under stand why you're converting the character to a string. Your reasoning was so that you could do the IF conparisons, but you can use chars in IFs so I'm not sure what you mean.

Ken
"VMI" <vo******@yahoo .com> wrote in message
news:%2******** ********@TK2MSF TNGP09.phx.gbl. ..

I have a really simple IF statement that looks like this:

if (sNewString.Len gth == iCount)
{
MessageBox.Show (sNewString.Len gth.ToString() + " is equal to " +
iCount.ToString () + "*" + sNewString + "*");
}
if (sNewString.Tri m() == "")
{
MessageBox.Show ("");
}
if (sNewString.Len gth == 0)
{
MessageBox.Show ("Length equals 0");
}
if (sNewString == null)
{
MessageBox.Show ("NULL");
}
if (sNewString.Len gth<iCount)
{
MessageBox.Show ("sNewString.Le ngth<iCount");
}
if (sNewString.Len gth>iCount)
{
MessageBox.Show ("sNewString.Le ngth>iCount");
}

When the debugger reaches the first IF, the debugger shows that
sNewString.Leng th = 0, iCount = 1, and sNewString = "". The frustrating
thing is that it only enters the first IF ("sNewString.Le ngth == iCount") and the MessageBox displays "1 is equal to 1*" at exactly the same time

the

debugger's showing that sNewString.Leng th = 0 and iCount = 1. How can this be possible? The messagebox and the debugger are showing different
information. I did notice that the MessageBox didn't display the last '*' (anything after this instance of sNewString is truncated) but I have

another

IF statement that checks for NULL but it never enters that IF.
The only thing I can think of is that, before these comparisons, I convert this specific char into a string (the byte value of this specific char is equal to 0) so I can do the IF comparisons. But that's it.

Any information is really appreciated.

[Jon Skeet [C# MVP]]

VMI <vo******@yahoo .com> wrote:

I imagined that could've been it.
These IF statements are in another method that receive a string as
parameter. Most of the times this method is called with a string, but in
certain cases, I need to pass this char as parameter. So I convert the char
to string, and then call the method.
Once I convert this char to string, how can I distinguish between a null
string, an empty string, and this string?

if (x==null) // Null string

if (x.Length==0) // Empty string

if (x=="\0") // String with a single character in, the nul character

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

[mikeb]

VMI wrote:

When the debugger reaches the first IF, the debugger shows that
sNewString.Leng th = 0, iCount = 1, and sNewString = "". The frustrating
thing is that it only enters the first IF ("sNewString.Le ngth == iCount")
and the MessageBox displays "1 is equal to 1*" at exactly the same time the
debugger's showing that sNewString.Leng th = 0 and iCount = 1. How can this
be possible? The messagebox and the debugger are showing different
information.

Unfortunately, the the debugger interprets strings using C language
semantics (ie., the string is terminated with a NULL character). .NET
strings can contain a NULL character, but any such string will be
displayed improperly by the debugger.

In your case, you probably have a string with a single '\0' character in it.
--
mikeb

[VMI]

Yes. That was it.

Thanks.

"Jon Skeet [C# MVP]" <sk***@pobox.co m> wrote in message
news:MP******** *************** *@msnews.micros oft.com...

VMI <vo******@yahoo .com> wrote:

I imagined that could've been it.
These IF statements are in another method that receive a string as
parameter. Most of the times this method is called with a string, but in
certain cases, I need to pass this char as parameter. So I convert the char to string, and then call the method.
Once I convert this char to string, how can I distinguish between a null
string, an empty string, and this string?

if (x==null) // Null string

if (x.Length==0) // Empty string

if (x=="\0") // String with a single character in, the nul character

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

[Stu Smith]

"VMI" <vo******@yahoo .com> wrote in message
news:%2******** ********@TK2MSF TNGP09.phx.gbl. ..

I have a really simple IF statement that looks like this:

if (sNewString.Len gth == iCount)
{
MessageBox.Show (sNewString.Len gth.ToString() + " is equal to " +
iCount.ToString () + "*" + sNewString + "*");
}
if (sNewString.Tri m() == "")
{
MessageBox.Show ("");
}
if (sNewString.Len gth == 0)
{
MessageBox.Show ("Length equals 0");
}
if (sNewString == null)
NB This will never fire. You'll get a NullReferenceEx ception on the first
test (property Length) if the reference is null. You need this test before
all the others.
{
MessageBox.Show ("NULL");
}
if (sNewString.Len gth<iCount)
{
MessageBox.Show ("sNewString.Le ngth<iCount");
}
if (sNewString.Len gth>iCount)
{
MessageBox.Show ("sNewString.Le ngth>iCount");
}

When the debugger reaches the first IF, the debugger shows that
sNewString.Leng th = 0, iCount = 1, and sNewString = "". The frustrating
thing is that it only enters the first IF ("sNewString.Le ngth == iCount")
and the MessageBox displays "1 is equal to 1*" at exactly the same time the debugger's showing that sNewString.Leng th = 0 and iCount = 1. How can this
be possible? The messagebox and the debugger are showing different
information. I did notice that the MessageBox didn't display the last '*'
(anything after this instance of sNewString is truncated) but I have another IF statement that checks for NULL but it never enters that IF.
The only thing I can think of is that, before these comparisons, I convert
this specific char into a string (the byte value of this specific char is
equal to 0) so I can do the IF comparisons. But that's it.

Any information is really appreciated.