Re: return a string


Nascimento wrote:
> Hello,
>
> How to I do to return a string as a result of a function.
> I wrote the following function:
>

There are two ways to "return" a string from a function. One is to
simply return it...

> char prt_tralha(int num)

I.E. char * ptr_tralha(int num)

Here we return a pointer to char, or string. The problem with this is
the return value can't be an automatic variable, so you'll need to work
with malloc.

Another method is to make the string part of the argument list. This is
probably prefered, since the memory management takes place outside of
the function and is (arguably) easier.

I.E. char ptr_tralha(int num, char *ret)

> {
> int i;
> char tralha[num];

Assuming the later method, tralha would simply be the argument to this
function, and not declared here.

>
> tralha = "#";
> for( i = 0; i < num-1; i++ )
> strcpy(tralha, strcat(tralha,"#"));
>
> return tralha;

There would be no need to "return" tralha here, since it was passed in
via pointer in the argument list.

> }
>
> And I really like to use it, thus:
>
> int main()
> {
> printf("%s \n", prt_tralha(5));

try this instead:

char tralha[5];
ptr_tralha(5,tralha);
printf("%s \n", tralha);

>
> return 0;
> }
>
> But when I compile it, gcc shows this message:
>
> tmp.c: In function `prt_tralha':
> tmp.c:16: error: incompatible types in assignment

Well, of course. The function is (was) returning a char, but you were
trying to use it as if it were a char *.

> tmp.c:20: warning: return makes integer from pointer without a cast
> tmp.c:20: warning: function returns address of local variable
>
> Thanks,

Hope this helps. I'm sure others will have suggestions as well.

-Jason
>
> Nascimento

.

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