higijj
asked on
returning a ref
Hi!
I created a struct. Now, I want to create a function that will return a pointer to my newly created struct. my question is how to do so? Can I just create a local struct in my function and return it with the & operator?
Here is my simplified struct:
typedef struct {
char *subject[MAX_SUBJECT];
char *body[MAX_BODY][LINE_WIDTH
} creative;
here is my function's prototype:
creative *Initialize_Creative(const
so in the body of this function, could I do like:
{
creative to_return;
// initialize it from the file
return &to_return;
}
I don't think this could work, cuz when the function ends, the scope of my struct should go out. So what's the right way to do this?
Thanks a lot,
HiGiJJ!
I created a struct. Now, I want to create a function that will return a pointer to my newly created struct. my question is how to do so? Can I just create a local struct in my function and return it with the & operator?
Here is my simplified struct:
typedef struct {
char *subject[MAX_SUBJECT];
char *body[MAX_BODY][LINE_WIDTH
} creative;
here is my function's prototype:
creative *Initialize_Creative(const
so in the body of this function, could I do like:
{
creative to_return;
// initialize it from the file
return &to_return;
}
I don't think this could work, cuz when the function ends, the scope of my struct should go out. So what's the right way to do this?
Thanks a lot,
HiGiJJ!
it certainly will Hiqijj, but I thought this was "C" section rather than C++
regards,
codez80
regards,
codez80
ASKER
well isn't the above C ?
ASKER CERTIFIED SOLUTION
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ASKER
ok
so New is basically just a warper of malloc ?!
so New is basically just a warper of malloc ?!
Eh, and your struct needs a little bit correction.
Don't use * on the subject and body, if you mean them as array of char.
typedef struct {
char subject[MAX_SUBJECT];
char body[MAX_BODY][LINE_WIDTH]
} creative;
Don't use * on the subject and body, if you mean them as array of char.
typedef struct {
char subject[MAX_SUBJECT];
char body[MAX_BODY][LINE_WIDTH]
} creative;
ASKER
yteah
I modified it so it looks like
typedef struct {
char *subject;
char *body[LINE_WIDTH];
} creative;
I modified it so it looks like
typedef struct {
char *subject;
char *body[LINE_WIDTH];
} creative;
No, new is not JUST a wrapper of malloc.
It is a special C++ operator to create a new object, and it does:
1. automatically calculate the object size (malloc need explicit size)
2. allocate the memory (this is what malloc do).
3. Call the object constructor (malloc won't do this)
It is a special C++ operator to create a new object, and it does:
1. automatically calculate the object size (malloc need explicit size)
2. allocate the memory (this is what malloc do).
3. Call the object constructor (malloc won't do this)
ASKER
Thanks for the help/explanation!!
Helped me a lot!
HiGiJJ
Helped me a lot!
HiGiJJ
Then you should also malloc some memory for the subject and body one by one.
creative* initialize()
{
creative* c = malloc(sizeof(creative));
char init_subject[] = "SAMPLE";
c->subject = malloc(strlength(init_subj
strcpy(c->subject, init_subject);
return c;
}
Consequently, you have to free them also 1 by one;
void freeCreative(creative *c)
{
/* free from the last to the first */
free(c->body[LAST]);
...
free(c->subject);
free(c);
}
creative* initialize()
{
creative* c = malloc(sizeof(creative));
char init_subject[] = "SAMPLE";
c->subject = malloc(strlength(init_subj
strcpy(c->subject, init_subject);
return c;
}
Consequently, you have to free them also 1 by one;
void freeCreative(creative *c)
{
/* free from the last to the first */
free(c->body[LAST]);
...
free(c->subject);
free(c);
}
ASKER
so
{
creative to_return = new creative;
// initialize it from the file
return to_return;
}
would do the job :)