guess the output

[jt]

here is a program..
struct st
{
char ch[3];
int a;
}st_var={"ABC", 68};

void main()
{

printf("%s",st_ var.ch);

}

If there is continuous allocation then the output will be

ABCD

now...suppose tht the memory is not allocated continuously..
the first 3 bytes are allocated at 1 place and next 2 bytes are
allocated at other place
wht will be the output....???

[Richard Bos]

Re: guess the output

jt <karthiks.840@g mail.comwrote:

wht will be the output....???

You'd be better off not asking that question, and learning to write
programs that aren't broken instead. Any answer you do find will be
highly undependable, and likely to lead to crashes or worse further down
the line.

Richard

[Joachim Schmitz]

Re: guess the output

santosh wrote:

jt wrote:
>

>here is a program..
>struct st
>{
> char ch[3];
> int a;
>}st_var={"ABC" ,68};

>
Undefined behaviour. You are writing past the bounds of an object, in
this case 'ch'.
>

>void main()

>
int main(void)
>

>{
>>
> printf("%s",st_ var.ch);

>
return 0;
>

>>
>}
>>
>If there is continuous allocation then the output will be
>>
>ABCD

>
Only for the ASCII encoding.

And only for little endian machines...

Bye, Jojo

[Martin Ambuhl]

Re: guess the output

santosh wrote:

jt wrote:
>

>here is a program..
>struct st
>{
> char ch[3];
> int a;
>}st_var={"ABC" ,68};

>
Undefined behaviour. You are writing past the bounds of an object, in
this case 'ch'.

Not true. The initializer "ABC" is perfectly fine for char ch[3]. It
just won't give you a string.

[Joachim Schmitz]

Re: guess the output

Joachim Schmitz wrote:

santosh wrote:

>jt wrote:
>>

>>here is a program..
>>struct st
>>{
>> char ch[3];
>> int a;
>>}st_var={"ABC ",68};

>>
>Undefined behaviour. You are writing past the bounds of an object, in
>this case 'ch'.
>>

>>void main()

>>
>int main(void)
>>

>>{
>>>
>> printf("%s",st_ var.ch);

>>
>return 0;
>>

>>>
>>}
>>>
>>If there is continuous allocation then the output will be
>>>
>>ABCD

>>
>Only for the ASCII encoding.

And only for little endian machines...

And sizeof(int) == 2

Bye, Jojo

[Martin]

Re: guess the output

On Mon, 03 Mar 2008 14:48:00 -0000, Kenneth Brody <kenbrody@spamc op.net>
wrote:

>
Are you sure? I thought this was perfectly valid:
>
char chr[3] = "ABC";
>
In this case, it's simply shorthand for:
>
char chr[3] = { 'A', 'B', 'C' };
>
[...]

According to K&R2 it is correct:

If the array has unknown size, the number of
characters in the string, including the
terminating null character, determines its
size; if its size is fixed, the number of
characters in the string, not counting the
terminating null character, must not exceed
the size of the array. -- Section A8.7

Presumably this is an accurate interpretation of the standard that was
later ratified and referred to informally as C89.

--
Martin

[Richard Heathfield]

Re: guess the output

Martin said:

<snip>

If the array has unknown size, the number of
characters in the string, including the
terminating null character, determines its
size; if its size is fixed, the number of
characters in the string, not counting the
terminating null character, must not exceed
the size of the array. -- Section A8.7
>
Presumably this is an accurate interpretation of the standard that was
later ratified and referred to informally as C89.

Yes, and this oddity survives in C99, in 6.7.8(14):

"An array of character type may be initialized by a character string
literal, optionally enclosed in braces. Successive characters of the
character string literal (including the terminating null character if
there is room or if the array is of unknown size) initialize the
elements of the array."

--
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