«

I want to return an array from a function and catch it in an an array
variable.

For example like this

int main(){
int a[3];
a = get_value();
return 0;
}

int[] get_value(){
int b[3]={0,1,2};
return b;
}


This is a bit like Java. How to get this thing done in C.

Please help

wrote:
> I want to return an array from a function and catch it in an an array
> variable.
>
> For example like this
>
> int main(){
> int a[3];
> a = get_value();
> return 0;
> }
>
> int[] get_value(){
> int b[3]={0,1,2};
> return b;
> }
>
>
> This is a bit like Java. How to get this thing done in C.

C is not Java, and one of the differences (there are
many) is in the way arrays are implemented. It is sometimes
said that arrays are not "first-class citizens" in C, mostly
because there are only two operators that work on entire
arrays: the `sizeof' operator and the `&' address-of operator.
In particular, the `=' assignment operator doesn't work on
arrays, so your attempt at `a = get_value()' is doomed from
the start.

What to do instead? Well, it depends on what you want
to accomplish. Take a step back, realize that you're not
writing Java, and don't let the syntactic similarity of C
and Java sucker you into trying to use Java techniques in a
C program. "Gift" is a perfectly good noun in both English
and German (closely-related languages), but while you might
give one to a friend you would not give it to a Freund.

So: What's the larger problem you're trying to solve?

--
Eric Sosman
lid

"Eric Sosman" writes:

>> I want to return an array from a function and catch it in an an array
>> variable.
>>
>> For example like this
>>
>> int main(){
>> int a[3];
>> a = get_value();
>> return 0;
>> }
>>
>> int[] get_value(){
>> int b[3]={0,1,2};
>> return b;
>> }
>>
>>
>> This is a bit like Java. How to get this thing done in C.
>
> C is not Java, and one of the differences (there are
> many) is in the way arrays are implemented. It is sometimes
> said that arrays are not "first-class citizens" in C, mostly
> because there are only two operators that work on entire
> arrays: the `sizeof' operator and the `&' address-of operator.
> In particular, the `=' assignment operator doesn't work on
> arrays, so your attempt at `a = get_value()' is doomed from
> the start.
>
> What to do instead? Well, it depends on what you want
> to accomplish. Take a step back, realize that you're not
> writing Java, and don't let the syntactic similarity of C
> and Java sucker you into trying to use Java techniques in a
> C program. "Gift" is a perfectly good noun in both English
> and German (closely-related languages), but while you might
> give one to a friend you would not give it to a Freund.
>
> So: What's the larger problem you're trying to solve?

I wasn't going to reply, but since I don't give a good God damn what the
larger problem you are trying to solve is, herewith my reply.

void fill(int b[])
{
for(int i=0; i<3; i++)
b[i] = i;
}
int main()
{
int a[3];
fill(a);
return 0;
}
----
There is nothing to return, a is modified in place.

writes:
> I want to return an array from a function and catch it in an an array
> variable.
>
> For example like this
>
> int main(){
> int a[3];
> a = get_value();
> return 0;
> }
>
> int[] get_value(){
> int b[3]={0,1,2};
> return b;
> }
>
>
> This is a bit like Java. How to get this thing done in C.

Array types are second-class citizens in C. You can't assign them or
return them from functions. You need to use pointers.

If you have a C textbook, read the sections on arrays and pointers.
If you don't, get one; I recommend Kernigan & Ritchie, _The C
Programming Language_, Second Edition.

See also section 6 of the comp.lang.c FAQ, <http://www.c-faq.com/>.

--
Keith Thompson (The_Other_Keith) kst- <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.

osmium wrote:
[snip]
> void fill(int b[])
> {
> for(int i=0; i<3; i++)
> b[i] = i;
> }

Or better:

void fill(int b[], int len)
{
for (int i = 0; i < len; i++)
b[i] = i;
}


August

--
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.

hi, all!
i think, you can write something, like that:

int * get_array(int size){
int i, *ptr = malloc(sizeof(int) * size); /* memory allocate*/
for(i = 0; i < size; i++){
ptr[i] = i; /* fill array*/
}
return ptr; /* return pointer to array */
}

and from main it look like that:
int i, size = 10, * arr = get_array(size);
for(i = 0; i < size; i++){
printf("%d\n", arr[i]);
}

p.s sorry for my english
------------------------
best regards
Alexander Chugaevsky
icq: 314285577

wrote:
> hi, all!
> i think, you can write something, like that:
>
> int * get_array(int size){
> int i, *ptr = malloc(sizeof(int) * size); /* memory allocate*/
> for(i = 0; i < size; i++){
> ptr[i] = i; /* fill array*/
> }
> return ptr; /* return pointer to array */
> }
>
> and from main it look like that:
> int i, size = 10, * arr = get_array(size);
> for(i = 0; i < size; i++){
> printf("%d\n", arr[i]);
> }

It is more flexible to let the client supply the buffer to be filled.

> p.s sorry for my english

No problem, but correct capitalization will certainly help.


August

--
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.

wrote:
> hi, all!
> i think, you can write something, like that:
>
> int * get_array(int size){
> int i, *ptr = malloc(sizeof(int) * size); /* memory allocate*/
> for(i = 0; i < size; i++){
> ptr[i] = i; /* fill array*/
> }
> return ptr; /* return pointer to array */
> }
>
> and from main it look like that:
> int i, size = 10, * arr = get_array(size);
> for(i = 0; i < size; i++){
> printf("%d\n", arr[i]);
> }
>
> p.s sorry for my english
> ------------------------
> best regards
> Alexander Chugaevsky
> icq: 314285577

Hi
Please don't forget to clean up by free()ing your malloc()ed array.
Regards,
Frodo Drogo Baggins