C Variables Length

**user923005** · Dec 14 '07, 11:05 PM

Re: C Variables Length

On Dec 14, 2:53 pm, lak <l...@nospam.in validwrote:

Hello firends.
I want to know what is the variable length in c.
I K&R they stated that atleast 31 character.
But I give 1 lakhs length to a variable, but my compiler doesn't say
any error.
It accepts it.Then what is the maximum length to a variable.?

A more appropriate reference is the C language standard. It says:

5.2.4.1 Translation limits
1 The implementation shall be able to translate and execute at least
one program that contains at least one instance of every one of the
following limits:13)
* 127 nesting levels of blocks
* 63 nesting levels of conditional inclusion
* 12 pointer, array, and function declarators (in any combinations)
modifying an arithmetic, structure, union, or incomplete type in a
declaration
* 63 nesting levels of parenthesized declarators within a full
declarator
* 63 nesting levels of parenthesized expressions within a full
expression
* 63 significant initial characters in an internal identifier or a
macro name (each universal character name or extended source character
is considered a single character)
* 31 significant initial characters in an external identifier (each
universal character name specifying a short identifier of 0000FFFF or
less is considered 6 characters, each universal character name
specifying a short identifier of 00010000 or more is considered 10
characters, and each extended source character is considered the same
number of characters as the corresponding universal character name, if
any)14)
* 4095 external identifiers in one translation unit
* 511 identifiers with block scope declared in one block
* 4095 macro identifiers simultaneously defined in one preprocessing
translation unit
* 127 parameters in one function definition
* 127 arguments in one function call
* 127 parameters in one macro definition
* 127 arguments in one macro invocation
* 4095 characters in a logical source line
* 4095 characters in a character string literal or wide string literal
(after concatenation)
* 65535 bytes in an object (in a hosted environment only)
* 15 nesting levels for #included files
* 1023 case labels for a switch statement (excluding those for any
nested switch statements)
* 1023 members in a single structure or union
* 1023 enumeration constants in a single enumeration
* 63 levels of nested structure or union definitions in a single
struct-declaration-list

So you can have up to 63 *initial* characters in an internal
identifier. That means you might make one 100 characters long, but
only the first 63 would be recognized to differentiate it from other
identifiers.
Some pre-C99 implementations may limit to 31 *initial* characters in
an internal identifier. That means you might make one 100 characters
long, but only the first 31 would be recognized to differentiate it
from other identifiers.

**Ben Pfaff** · Dec 14 '07, 11:15 PM

Re: C Variables Length

lak <lak@nospam.inv alidwrites:

I want to know what is the variable length in c.
I K&R they stated that atleast 31 character.
But I give 1 lakhs length to a variable, but my compiler doesn't say
any error.

The number of significant characters in an identifier varies
among implementations . It is at least 31 for internal
identifiers and 6 for external identifiers in C90, and higher
than that in each case for C99.

I don't know what a "lakh" is.
--
char a[]="\n .CJacehknorstu" ;int putchar(int);in t main(void){unsi gned long b[]
={0x67dffdff,0x 9aa9aa6a,0xa77f fda9,0x7da6aa6a ,0xa67f6aaa,0xa a9aa9f6,0x11f6} ,*p
=b,i=24;for(;p+ =!*p;*p/=4)switch(0[p]&3)case 0:{return 0;for(p--;i--;i--)case+
2:{i++;if(i)bre ak;else default:continu e;if(0)case 1:putchar(a[i&15]);break;}}}

**Eric Sosman** · Dec 14 '07, 11:15 PM

Re: C Variables Length

Ben Pfaff wrote:

lak <lak@nospam.inv alidwrites:
>

>I want to know what is the variable length in c.
>I K&R they stated that atleast 31 character.
>But I give 1 lakhs length to a variable, but my compiler doesn't say
>any error.

>
The number of significant characters in an identifier varies
among implementations . It is at least 31 for internal
identifiers and 6 for external identifiers in C90, and higher
than that in each case for C99.
>
I don't know what a "lakh" is.

1E5, or GIYF.

--
Eric Sosman
esosman@ieee-dot-org.invalid

**Richard Heathfield** · Dec 14 '07, 11:25 PM

Re: C Variables Length

Ben Pfaff said:

lak <lak@nospam.inv alidwrites:
>

>I want to know what is the variable length in c.
>I K&R they stated that atleast 31 character.
>But I give 1 lakhs length to a variable, but my compiler doesn't say
>any error.

>
The number of significant characters in an identifier varies
among implementations . It is at least 31 for internal
identifiers and 6 for external identifiers in C90, and higher
than that in each case for C99.
>
I don't know what a "lakh" is.

According to Chambers Dictionary, it's 100,000.

--
Richard Heathfield <http://www.cpax.org.uk >
Email: -http://www. +rjh@
Google users: <http://www.cpax.org.uk/prg/writings/googly.php>
"Usenet is a strange place" - dmr 29 July 1999

**Default User** · Dec 14 '07, 11:35 PM

Re: C Variables Length

Ben Pfaff wrote:

lak <lak@nospam.inv alidwrites:

But I give 1 lakhs length to a variable, but my compiler doesn't say
any error.

I don't know what a "lakh" is.

It was a surprise to me to find it in Merriam-Webster online:

<http://m-w.com/dictionary/lakh>

Brian

**CBFalconer** · Dec 15 '07, 12:45 AM

Re: C Variables Length

Eric Sosman wrote:

Ben Pfaff wrote:

>lak <lak@nospam.inv alidwrites:
>>

>>I want to know what is the variable length in c.
>>I K&R they stated that atleast 31 character.
>>But I give 1 lakhs length to a variable, but my compiler doesn't
>>say any error.

>>
>The number of significant characters in an identifier varies
>among implementations . It is at least 31 for internal
>identifiers and 6 for external identifiers in C90, and higher
>than that in each case for C99.
>>
>I don't know what a "lakh" is.

>
1E5, or GIYF.

Around here it is assumed to be a hairy ruminant cloven-hoofed
moss-eating cold-weather animal, with an evil taste. :-)
(Endangered specied)

--
Chuck F (cbfalconer at maineline dot net)
<http://cbfalconer.home .att.net>
Try the download section.

--
Posted via a free Usenet account from http://www.teranews.com

**jaysome** · Dec 15 '07, 08:25 AM

Re: C Variables Length

On Fri, 14 Dec 2007 15:07:02 -0800, Ben Pfaff <blp@cs.stanfor d.edu>
wrote:

>lak <lak@nospam.inv alidwrites:
>

>I want to know what is the variable length in c.
>I K&R they stated that atleast 31 character.
>But I give 1 lakhs length to a variable, but my compiler doesn't say
>any error.

>
>The number of significant characters in an identifier varies
>among implementations . It is at least 31 for internal
>identifiers and 6 for external identifiers in C90, and higher
>than that in each case for C99.

So, if I declared functions with external linkage like the following
in C90, then the behavior would be undefined, right?

void *avl_t_first (struct avl_traverser *, struct avl_table *);
void *avl_t_find (struct avl_traverser *, struct avl_table *, void *);

I'm using a C90 compiler.

If I use such code, could it format my hard drive?
If I use such code, could it cause WWIII?
If I use such code, on the Deathstation 9000, could it cause demons to
fly out of my nose?
If I use such code, could it cause Scott Nudds to come flying out of
my nose?
If I use such code, could it <insert your favorite consequence of
undefined behavior here>?

--
jay

**santosh** · Dec 15 '07, 11:35 AM

Re: C Variables Length

lak wrote:

Hello firends.
I want to know what is the variable length in c.
I K&R they stated that atleast 31 character.
But I give 1 lakhs length to a variable, but my compiler doesn't say
any error.
It accepts it.Then what is the maximum length to a variable.?

You asked this same question some time back. Couldn't you be bothered to
read the answers then given to you?

**Ben Pfaff** · Dec 15 '07, 05:15 PM

Re: C Variables Length

jaysome <jaysome@hotmai l.comwrites:

So, if I declared functions with external linkage like the following
in C90, then the behavior would be undefined, right?
>
void *avl_t_first (struct avl_traverser *, struct avl_table *);
void *avl_t_find (struct avl_traverser *, struct avl_table *, void *);
>
I'm using a C90 compiler.

Much code assumes that more than 6 characters are significant in
external identifiers.
--
Ben Pfaff

Ben Pfaff: Older postings

http://benpfaff.org

**Francine.Neary@googlemail.com** · Dec 16 '07, 10:35 PM

Re: C Variables Length

On Dec 14, 11:14 pm, Eric Sosman <esos...@ieee-dot-org.invalidwrot e:

Ben Pfaff wrote:

lak <l...@nospam.in validwrites:

>

I want to know what is the variable length in c.
I K&R they stated that atleast 31 character.
But I give 1 lakhs length to a variable, but my compiler doesn't say
any error.

>

The number of significant characters in an identifier varies
among implementations . It is at least 31 for internal
identifiers and 6 for external identifiers in C90, and higher
than that in each case for C99.

>

I don't know what a "lakh" is.

>
1E5, or GIYF.

In that case I'd advise the OP against using name of this length for
his variables - it might make his code hard to read, and the danger of
typos would be non-negligible. :)

>
--
Eric Sosman
esos...@ieee-dot-org.invalid

**santosh** · Dec 17 '07, 07:05 AM

Re: C Variables Length

Francine.Neary@ googlemail.com wrote:

On Dec 14, 11:14 pm, Eric Sosman <esos...@ieee-dot-org.invalidwrot e:

>Ben Pfaff wrote:

lak <l...@nospam.in validwrites:

>>

>I want to know what is the variable length in c.
>I K&R they stated that atleast 31 character.
>But I give 1 lakhs length to a variable, but my compiler doesn't
>say any error.

>>

The number of significant characters in an identifier varies
among implementations . It is at least 31 for internal
identifiers and 6 for external identifiers in C90, and higher
than that in each case for C99.

>>

I don't know what a "lakh" is.

>>
> 1E5, or GIYF.

>
In that case I'd advise the OP against using name of this length for
his variables - it might make his code hard to read, and the danger of
typos would be non-negligible. :)

The OP is apparently a troll, as he posted the very same "question" a
while back, and got more than adequate responses. If he isn't a troll,
then, one is forced to the much more distressing conclusion that he is
incapable of learning and comprehension.

C Variables Length

C Variables Length

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