va_list

[ramu]

Hi,
Can we intialize va_list to NULL?
ie. va_list = NULL

Regards

[Keith Thompson]

ramu <ra******@gmail.comwrites:

Can we intialize va_list to NULL?
ie. va_list = NULL

Probably not. va_list is "an object type suitable for holding
information needed by the macros va_start, va_arg, va_end, and
va_copy"; it's unlikely to be a pointer type.

What are you trying to accomplish?

--
Keith Thompson (The_Other_Keith) ks***@mib.org <http://www.ghoti.net/~kst>
San Diego Supercomputer Center <* <http://users.sdsc.edu/~kst>
"We must do something. This is something. Therefore, we must do this."
-- Antony Jay and Jonathan Lynn, "Yes Minister"

[=?iso-2022-kr?q?=1B=24=29CHarald_van_D=0E=29=26=0F]

On Thu, 11 Oct 2007 12:37:07 -0700, Keith Thompson wrote:

ramu <ra******@gmail.comwrites:

> Can we intialize va_list to NULL?
ie. va_list = NULL

Probably not. va_list is "an object type suitable for holding
information needed by the macros va_start, va_arg, va_end, and va_copy";
it's unlikely to be a pointer type.

I have one implementation where va_list is a typedef for char *, and know
of one where it's a typedef for void *. Also, implementations are allowed
to define NULL as 0, which is a valid initialiser for all scalar types. I
wouldn't say we can "probably" not initialise a va_list to NULL, just
that it's not portable and a bad idea even on the systems that do allow
it.

[ramu]

On Oct 11, 3:37 pm, Keith Thompson <[e-mail]:

ramu <[e-mail]:

Can we intialize va_list to NULL?
ie. va_list = NULL

Probably not. va_list is "an object type suitable for holding
information needed by the macros va_start, va_arg, va_end, and
va_copy"; it's unlikely to be a pointer type.

What are you trying to accomplish?

--
Keith Thompson (The_Other_Keith) [e-mail] <http://www.ghoti.net/~kst>
San Diego Supercomputer Center <* <http://users.sdsc.edu/~kst>
"We must do something. This is something. Therefore, we must do this."
-- Antony Jay and Jonathan Lynn, "Yes Miniss

Sorry. I meant va_list ap=NULL;
Not va_list = NULL;

[Keith Thompson]

ramu <ra******@gmail.comwrites:

On Oct 11, 3:37 pm, Keith Thompson <[e-mail]:

>ramu <[e-mail]:

Can we intialize va_list to NULL?
ie. va_list = NULL

Probably not. va_list is "an object type suitable for holding
information needed by the macros va_start, va_arg, va_end, and
va_copy"; it's unlikely to be a pointer type.

What are you trying to accomplish?

Sorry. I meant va_list ap=NULL;
Not va_list = NULL;

Please don't quote signatures (the stuff following the "-- " line)
unless you're actually commenting on them.

I assumed that was what you meant; I actually missed the fact that you
assigned a value to a type rather than to a variable.

But again, va_list is not necessarily a pointer type, and assigning a
null value to a va_list object, as far as I can tell, doesn't make any
sense.

And again, what are you trying to accomplish?

--
Keith Thompson (The_Other_Keith) ks***@mib.org <http://www.ghoti.net/~kst>
San Diego Supercomputer Center <* <http://users.sdsc.edu/~kst>
"We must do something. This is something. Therefore, we must do this."
-- Antony Jay and Jonathan Lynn, "Yes Minister"

[ramu]

On Oct 12, 2:39 am, Keith Thompson <[e-mail]:

ramu <[e-mail]:

On Oct 11, 3:37 pm, Keith Thompson <[e-mail]:

ramu <[e-mail]:
Can we intialize va_list to NULL?
ie. va_list = NULL

Probably not. va_list is "an object type suitable for holding
information needed by the macros va_start, va_arg, va_end, and
va_copy"; it's unlikely to be a pointer type.

What are you trying to accomplish?

Sorry. I meant va_list ap=NULL;
Not va_list = NULL;

Please don't quote signatures (the stuff following the "-- " line)
unless you're actually commenting on them.

I assumed that was what you meant; I actually missed the fact that you
assigned a value to a type rather than to a variable.

But again, va_list is not necessarily a pointer type, and assigning a
null value to a va_list object, as far as I can tell, doesn't make any
sense.

And again, what are you trying to accomplish?

Am getting Lint warning saying that variable is not initialized.
So am trying to initialize ap to NULL.

[Peter Nilsson]

ramu <[e-mail]:

Keith Thompson <[e-mail]:

Can we intialize va_list to NULL?

... va_list is not necessarily a pointer type, and
assigning a null value to a va_list object, as far as I
can tell, doesn't make any sense.

And again, what are you trying to accomplish?

Am getting Lint warning saying that variable is not
initialized. So am trying to initialize ap to NULL.

va_list ap = { 0 };

You can initialise _any_ object with { 0 }. However, if you're
just doing this to silence one warning, realise that applying
a fix may simply raise an alternative warning.

Apart from fixing actual errors, you shouldn't be letting
implementations (or tools thereof) dictate how you write
your code.

Too many programmers fall into the trap of adding needless
casts because a compiler is beeping at them without it.
Because they haven't checked whether there is an actual
problem with the code, they inadvertently add one thinking
that if the compiler has stopped complaining, the code
must be correct.

--
Peter