Empty Character Literal

[VJ]

I have a property for a control ( source code not available) . The property
accepts single char as value.. so I can set it to '/' or ':' or anything
like that...At initialize of my From I want this property to be set to a
empty literal. I am able to do this at design time using VS.NET property
box. This works for controls created at design time, but for some controls I
create at run-time I want to do the same at Form_load..

VJ

[Paul E Collins]

There is no "empty character literal", because every possible value
for a char type is one character long. You can have zero length
strings ("") but not zero-length characters, e.g. this will not
compile:

char ch = ''; // doesn't work

The closest you can get is a space (' ') or a null character ('\0',
ASCII zero).

P.

[Jon Skeet [C# MVP]]

VJ <vi********@yahoo.com> wrote:

I have a property for a control ( source code not available) . The property
accepts single char as value.. so I can set it to '/' or ':' or anything
like that...At initialize of my From I want this property to be set to a
empty literal. I am able to do this at design time using VS.NET property
box. This works for controls created at design time, but for some controls I
create at run-time I want to do the same at Form_load..

There's no such thing as an "empty" character, any more than there's an
"empty integer". What's the property used for? Character 0 (the "null"
character) *might* be an appropriate start value, but it's hard to say
without more information.

--
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

[Christof Nordiek]

"VJ" <vi********@yahoo.com> schrieb im Newsbeitrag
news:uP*************@TK2MSFTNGP10.phx.gbl...

I have a property for a control ( source code not available) . The
property accepts single char as value.. so I can set it to '/' or ':' or
anything like that...At initialize of my From I want this property to be
set to a empty literal. I am able to do this at design time using VS.NET
property box. This works for controls created at design time, but for some
controls I create at run-time I want to do the same at Form_load..

VJ

If you can do it with VS.NET, simply do it and check the value while
runtime.
The you know, what character it is and set it in code.

[Kevin Spencer]

Just a technical note about this: The reason that you can have empty strings
is that a string is an array of char with a null terminator. That is, a
string is actually (in memory) one char longer than the actual string,
including the null terminator. A char, on the other hand, is not an array,
but a single char.

--
HTH,

Kevin Spencer
Microsoft MVP
..Net Developer
Ambiguity has a certain quality to it.

"Paul E Collins" <fi******************@CL4.org> wrote in message
news:di**********@nwrdmz02.dmz.ncs.ea.ibs-infra.bt.com...

There is no "empty character literal", because every possible value for a
char type is one character long. You can have zero length strings ("") but
not zero-length characters, e.g. this will not compile:

char ch = ''; // doesn't work

The closest you can get is a space (' ') or a null character ('\0', ASCII
zero).

P.

[Daniel Jin]

that is not true.

..net strings are not null terminated. the reason why you can have an
empty string is because it's perfectly legal to have a 0-length array.

Kevin Spencer wrote:

Just a technical note about this: The reason that you can have empty strings
is that a string is an array of char with a null terminator. That is, a
string is actually (in memory) one char longer than the actual string,
including the null terminator. A char, on the other hand, is not an array,
but a single char.

--
HTH,

Kevin Spencer
Microsoft MVP
.Net Developer
Ambiguity has a certain quality to it.

"Paul E Collins" <fi******************@CL4.org> wrote in message
news:di**********@nwrdmz02.dmz.ncs.ea.ibs-infra.bt.com...

There is no "empty character literal", because every possible value for a
char type is one character long. You can have zero length strings ("") but
not zero-length characters, e.g. this will not compile:

char ch = ''; // doesn't work

The closest you can get is a space (' ') or a null character ('\0', ASCII
zero).

P.

[VJ]

Ok I got this one... The property had a corresponding Int property which if
I set to zero then it achieved the same thing as setting to nothing using
VS.NET property window...

Thanks all for your input..
VJ

"VJ" <vi********@yahoo.com> wrote in message
news:uP*************@TK2MSFTNGP10.phx.gbl...

I have a property for a control ( source code not available) . The
property accepts single char as value.. so I can set it to '/' or ':' or
anything like that...At initialize of my From I want this property to be
set to a empty literal. I am able to do this at design time using VS.NET
property box. This works for controls created at design time, but for some
controls I create at run-time I want to do the same at Form_load..

VJ

[Kevin Spencer]

Well, Daniel, you made me do my homework. In fact, we were both wrong. The
truth is a bit more complex. It depends on the implementation used. If C# or
C++ is used, it is indeed an array of WCHAR. If C is used, it is a
null-terminated string.

Now for some aspirin...

--
HTH,

Kevin Spencer
Microsoft MVP
..Net Developer
Ambiguity has a certain quality to it.

"Daniel Jin" <sh********@yahoo.com> wrote in message
news:11*********************@g43g2000cwa.googlegro ups.com...

that is not true.

.net strings are not null terminated. the reason why you can have an
empty string is because it's perfectly legal to have a 0-length array.

Kevin Spencer wrote:

Just a technical note about this: The reason that you can have empty
strings
is that a string is an array of char with a null terminator. That is, a
string is actually (in memory) one char longer than the actual string,
including the null terminator. A char, on the other hand, is not an
array,
but a single char.

--
HTH,

Kevin Spencer
Microsoft MVP
.Net Developer
Ambiguity has a certain quality to it.

"Paul E Collins" <fi******************@CL4.org> wrote in message
news:di**********@nwrdmz02.dmz.ncs.ea.ibs-infra.bt.com...

> There is no "empty character literal", because every possible value for
> a
> char type is one character long. You can have zero length strings ("")
> but
> not zero-length characters, e.g. this will not compile:
>
> char ch = ''; // doesn't work
>
> The closest you can get is a space (' ') or a null character ('\0',
> ASCII
> zero).
>
> P.
>
>

[Daniel Jin]

I'm not sure what you mean by "depends on implemenation". according to Jon
Skeet's article on .NET string though, it is indeed null terminated
internally for p/invoke. so I was wrong, which makes my original point a
little inconsequential, that you don't need null termination for empty
strings, a 0-length array should do just fine.

"Kevin Spencer" wrote:

Well, Daniel, you made me do my homework. In fact, we were both wrong. The
truth is a bit more complex. It depends on the implementation used. If C# or
C++ is used, it is indeed an array of WCHAR. If C is used, it is a
null-terminated string.

Now for some aspirin...

--
HTH,

Kevin Spencer
Microsoft MVP
..Net Developer
Ambiguity has a certain quality to it.

"Daniel Jin" <sh********@yahoo.com> wrote in message
news:11*********************@g43g2000cwa.googlegro ups.com...

that is not true.

.net strings are not null terminated. the reason why you can have an
empty string is because it's perfectly legal to have a 0-length array.

Kevin Spencer wrote:

Just a technical note about this: The reason that you can have empty
strings
is that a string is an array of char with a null terminator. That is, a
string is actually (in memory) one char longer than the actual string,
including the null terminator. A char, on the other hand, is not an
array,
but a single char.

--
HTH,

Kevin Spencer
Microsoft MVP
.Net Developer
Ambiguity has a certain quality to it.

"Paul E Collins" <fi******************@CL4.org> wrote in message
news:di**********@nwrdmz02.dmz.ncs.ea.ibs-infra.bt.com...
> There is no "empty character literal", because every possible value for
> a
> char type is one character long. You can have zero length strings ("")
> but
> not zero-length characters, e.g. this will not compile:
>
> char ch = ''; // doesn't work
>
> The closest you can get is a space (' ') or a null character ('\0',
> ASCII
> zero).
>
> P.
>
>

[Bruce Wood]

By the way, just for your information C# 2.0 has the concept of
nullable types. There is still no such thing as the "empty character",
but in C# 2.0 you can say:

char? emptyChar = null;

which isn't quite what you were after, but I thought I'd mention it
because it's sort of related. :)