what is the difference between the 2 sentences?

[yezi]

Hi, all:

The 1st sendtence:

int main(){
char string[20]={""};
string[20] = {" connected "};
.....
}
The second sentence:
int main(){
char string[20]={""};
string[20]=" connected ";
....
}

Thanks for any comments;

bin YE

[Walter Roberson]

In article <11************ **********@o13g 2000cwo.googleg roups.com>,
yezi <ye*****@hotmai l.com> wrote:

The 1st sendtence: int main(){
char string[20]={""};
You set up an array of 20 char and initialize it with \0 in the first
position.
string[20] = {" connected "};
You then attempt to assign into the 21st char of that array. The
value you attempt to assign is, however, not a valid expression,
because {} in an expression context is a block grouping which does not
have an associated value. Unlike, for example, (a,b,c) in which the
associated value is the value of c (the comma operator).
....
} The second sentence:
int main(){
char string[20]={""};
You set up an array of 20 char and initialize it with \0 in the first
position.
string[20]=" connected ";
You then attempt to assign into the 21st char of that array. The
value you attempt to assign is, however, a pointer to a character
string.
...
}

You might want to explore the differences (if any) between

char string1[20] = "connected" ;
char string2[20] = { "connected" };
char string3[] = "connected" ;
char string4[] = { "connected" };
--
"It is important to remember that when it comes to law, computers
never make copies, only human beings make copies. Computers are given
commands, not permission. Only people can be given permission."
-- Brad Templeton

[August Karlstrom]

yezi wrote:

int main(){
char string[20]={""};
string[20] = {" connected "};
....
}

$ cat test.c
int main()
{
char string[20] = {""};
string[20] = {" connected "};
return 0;
}
$ gcc test.c
test.c: In function ¡®main¡¯:
test.c:4: error: syntax error before ¡®{¡¯ token
August

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I am the "ILOVEGNU" signature virus. Just copy me to your
signature. This email was infected under the terms of the GNU
General Public License.

[slebetman]

yezi wrote:

Hi, all:

The 1st sendtence:

int main(){
char string[20]={""};
string[20] = {" connected "};
....
}
The second sentence:
int main(){
char string[20]={""};
string[20]=" connected ";
...
}

Both "sentences" 1 and 2 are wrong because you attempt to assign a
string to a char. The value of string[0] or string[10] or string[19]
etc.. can only be a char.

Also trying to access string[20] is a memory access violation. This may
or may not crash your program depending on your OS and CPU. An array
that has the size of 20 elements may only have intexes up to 19.
Remember that in C, arrays are zero based. So, the maximum you can get
is string[19].

In addition, "sentence" 1 is wrong because the {brackets} are not valid
C constructs in that particular case.

[Christopher Benson-Manica]

yezi <ye*****@hotmai l.com> wrote:

int main(){
char string[20]={""};
string[20] = {" connected "};
}

In addition to the more helpful comments you have already received,
"string" is an identifier reserved for use by the implementation, and
you should thus not use it. (IIRC, that statement only applies if
you've included <string.h>.)

--
Christopher Benson-Manica | I *should* know what I'm talking about - if I
ataru(at)cybers pace.org | don't, I need to know. Flames welcome.

[David Resnick]

Christopher Benson-Manica wrote:

yezi <ye*****@hotmai l.com> wrote:

int main(){
char string[20]={""};
string[20] = {" connected "};
}

In addition to the more helpful comments you have already received,
"string" is an identifier reserved for use by the implementation, and
you should thus not use it. (IIRC, that statement only applies if
you've included <string.h>.)

--
Christopher Benson-Manica | I *should* know what I'm talking about - if I
ataru(at)cybers pace.org | don't, I need to know. Flames welcome.

str... is apparently only reserved for function names.
from n869:

7.26.10 General utilities <stdlib.h>

[#1] Function names that begin with str and a lowercase
letter (possibly followed by any combination of digits,
letters, and underscore) may be added to the declarations in
the <stdlib.h> header.

7.26.11 String handling <string.h>

[#1] Function names that begin with str, mem, or wcs and a
lowercase letter (possibly followed by any combination of
digits, letters, and underscore) may be added to the
declarations in the <string.h> header.

-David

-David

[David Resnick]

David Resnick wrote:

Christopher Benson-Manica wrote:

yezi <ye*****@hotmai l.com> wrote:

int main(){
char string[20]={""};
string[20] = {" connected "};
}

In addition to the more helpful comments you have already received,
"string" is an identifier reserved for use by the implementation, and
you should thus not use it. (IIRC, that statement only applies if
you've included <string.h>.)

--
Christopher Benson-Manica | I *should* know what I'm talking about - if I
ataru(at)cybers pace.org | don't, I need to know. Flames welcome.

str... is apparently only reserved for function names.
from n869:

7.26.10 General utilities <stdlib.h>

[#1] Function names that begin with str and a lowercase
letter (possibly followed by any combination of digits,
letters, and underscore) may be added to the declarations in
the <stdlib.h> header.

7.26.11 String handling <string.h>

[#1] Function names that begin with str, mem, or wcs and a
lowercase letter (possibly followed by any combination of
digits, letters, and underscore) may be added to the
declarations in the <string.h> header.

-David

I posted the above hastily. But isn't a variable at block scope
called str... OK? Or can the header make its functions macros, in
which
case this wouldn't fly either?

-David

[Mike Wahler]

"David Resnick" <ln********@gma il.com> wrote in message
news:11******** *************@o 13g2000cwo.goog legroups.com...

7.26.11 String handling <string.h>

[#1] Function names that begin with str, mem, or wcs and a
lowercase letter (possibly followed by any combination of
digits, letters, and underscore) may be added to the
declarations in the <string.h> header.

-David

I posted the above hastily. But isn't a variable at block scope
called str... OK? Or can the header make its functions macros, in
which
case this wouldn't fly either?

If strings could fly, we wouldn't need kites.

-Mike

[Christopher Benson-Manica]

David Resnick <ln********@gma il.com> wrote:

I posted the above hastily. But isn't a variable at block scope
called str... OK? Or can the header make its functions macros, in
which
case this wouldn't fly either?

IANALL, but I believe this paragraph from 7.1.3 applies...

"All identifiers with external linkage in any of the following
subclauses (including the future library directions) are always reserved
for use as identifiers with external linkage."

The wording of the text you posted seems to preclude the reserved str*
names being macros, so I think the paragraph concerning macro names
immediately preceding the above does not apply. So it seems that str*
are acceptable at block scope (as in OP's code) and at file scope, if
I've read this correctly.

--
Christopher Benson-Manica | I *should* know what I'm talking about - if I
ataru(at)cybers pace.org | don't, I need to know. Flames welcome.

[Christopher Benson-Manica]

Mike Wahler <mk******@mkwah ler.net> wrote:

If strings could fly, we wouldn't need kites.

And here I was reading your post anticipating an illuminating response
:-)

--
Christopher Benson-Manica | I *should* know what I'm talking about - if I
ataru(at)cybers pace.org | don't, I need to know. Flames welcome.