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switch { } - case for range


I was checking out the C-FAQ and read here (
http://c-faq.com/misc/nonconstcase.html ) that:
" case labels are limited to single, constant, integral expression ".

However, I have been using case with ranges for a long while ( gcc,
VC++) so either the FAQ calls for an update or those two compilers
provide this functionality as an extension.

example;
switch (a)
{
case 1 ... 10:
// code
break;

case 11 ... 50:
// code
break;

case 800:
// code
break;

default:
// code
break;
}

Sep 6 '06 #1
21 52360
"markpapada kis" <ma***********@ gmail.comwrites :
I was checking out the C-FAQ and read here (
http://c-faq.com/misc/nonconstcase.html ) that:
" case labels are limited to single, constant, integral expression ".

However, I have been using case with ranges for a long while ( gcc,
VC++) so either the FAQ calls for an update or those two compilers
provide this functionality as an extension.
It's an extension.
--
Go not to Usenet for counsel, for they will say both no and yes.
Sep 6 '06 #2
BRG
markpapadakis wrote:
I was checking out the C-FAQ and read here (
http://c-faq.com/misc/nonconstcase.html ) that:
" case labels are limited to single, constant, integral expression ".

However, I have been using case with ranges for a long while ( gcc,
VC++) so either the FAQ calls for an update or those two compilers
provide this functionality as an extension.

example;
switch (a)
{
case 1 ... 10:
// code
break;

case 11 ... 50:
// code
break;

case 800:
// code
break;

default:
// code
break;
}
This doesn't work with VC++ version 8 and I don't recall it working on
earlier versions either.

Brian Gladman

Sep 6 '06 #3
markpapadakis wrote:
I was checking out the C-FAQ and read here (
http://c-faq.com/misc/nonconstcase.html ) that:
" case labels are limited to single, constant, integral expression ".

However, I have been using case with ranges for a long while ( gcc,
VC++) so either the FAQ calls for an update or those two compilers
provide this functionality as an extension.
[snip example]

C doesn't have ranges. What you describe is an extension, one which is
clearly documented as such in the gcc documentation. What version of
VC++ are you using that allows this?

Robert Gamble

Sep 6 '06 #4

Robert Gamble wrote:
markpapadakis wrote:
I was checking out the C-FAQ and read here (
http://c-faq.com/misc/nonconstcase.html ) that:
" case labels are limited to single, constant, integral expression ".

However, I have been using case with ranges for a long while ( gcc,
VC++) so either the FAQ calls for an update or those two compilers
provide this functionality as an extension.

[snip example]

C doesn't have ranges. What you describe is an extension, one which is
clearly documented as such in the gcc documentation. What version of
VC++ are you using that allows this?

Robert Gamble
I was wrong. It does not work with VC++. It has been a long while since
I used it and I thought it was supported there as well.

Thank you for the answer to the question.

Sep 6 '06 #5
markpapadakis wrote:
I was checking out the C-FAQ and read here (
http://c-faq.com/misc/nonconstcase.html ) that:
" case labels are limited to single, constant, integral expression ".

However, I have been using case with ranges for a long while ( gcc,
VC++) so either the FAQ calls for an update or those two compilers
provide this functionality as an extension.
It's an extension.

--
Clark S. Cox III
cl*******@gmail .com
Sep 6 '06 #6
markpapadakis wrote:
I was checking out the C-FAQ and read here (
http://c-faq.com/misc/nonconstcase.html ) that:
" case labels are limited to single, constant, integral expression ".

However, I have been using case with ranges for a long while ( gcc,
VC++) so either the FAQ calls for an update or those two compilers
provide this functionality as an extension.

example;
switch (a)
{
case 1 ... 10:
// code
break;

case 11 ... 50:
// code
break;

case 800:
// code
break;

default:
// code
break;
}
What is your experience with this extension?

Is it really useful?

How many times did you use it?

I would be interested in knowing if it makjes sense to
implement it in lcc-win32.

jacob
Sep 6 '06 #7
On Wed, 06 Sep 2006 22:09:45 +0200, in comp.lang.c , jacob navia
<ja***@jacob.re mcomp.frwrote:
>markpapadaki s wrote:
>switch (a)
{

What is your experience with this extension?
For what its worth, my experience is that its really useful if you're
a Visual Basic programmer trying to write C in the style of VB.

For myself I consider this A Very Bad Idea (tm), never ever try to use
one language in the idiom of another. Consider the early editions of
Num Rec in C as a classic case-study. I mean, why buy a scooter to
haul logs?
--
Mark McIntyre

"Debugging is twice as hard as writing the code in the first place.
Therefore, if you write the code as cleverly as possible, you are,
by definition, not smart enough to debug it."
--Brian Kernighan
Sep 6 '06 #8

jacob navia wrote:
markpapadakis wrote:
I was checking out the C-FAQ and read here (
http://c-faq.com/misc/nonconstcase.html ) that:
" case labels are limited to single, constant, integral expression ".

However, I have been using case with ranges for a long while ( gcc,
VC++) so either the FAQ calls for an update or those two compilers
provide this functionality as an extension.

example;
switch (a)
{
case 1 ... 10:
// code
break;

case 11 ... 50:
// code
break;

case 800:
// code
break;

default:
// code
break;
}

What is your experience with this extension?

Is it really useful?

How many times did you use it?

I would be interested in knowing if it makjes sense to
implement it in lcc-win32.

jacob

I am using it quite often. Its useful it eliminates the need for
conditional statements ( wherever conditional statements can be used,
of course ) , provides for easier to manage/understand code and perhaps
reaps any performance benefits versus conditional statements.

Mark

Sep 6 '06 #9
markpapadakis wrote:
jacob navia wrote:
>markpapadaki s wrote:
>>I was checking out the C-FAQ and read here (
http://c-faq.com/misc/nonconstcase.html ) that:
" case labels are limited to single, constant, integral
expression ".

However, I have been using case with ranges for a long while
( gcc, VC++) so either the FAQ calls for an update or those
two compilers provide this functionality as an extension.

example;
switch (a)
{
case 1 ... 10:
// code
break;

case 11 ... 50:
// code
break;

case 800:
// code
break;

default:
// code
break;
}

What is your experience with this extension?

Is it really useful?

How many times did you use it?

I would be interested in knowing if it makjes sense to
implement it in lcc-win32.

I am using it quite often. Its useful it eliminates the need for
conditional statements ( wherever conditional statements can be
used, of course ) , provides for easier to manage/understand code
and perhaps reaps any performance benefits versus conditional
statements.
Why in heavens name use it and become non-portable, when the
portable code (following) is clearer:

if ((a >= 1) && (a <= 10)) firstcode();
else if ((a 10) && (a <= 50)) secondcode();
else if (a == 800) thirdcode();
else defaultcode();

--
Chuck F (cbfalconer at maineline dot net)
Available for consulting/temporary embedded and systems.
<http://cbfalconer.home .att.net>
Sep 7 '06 #10

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