char * string has to be free() or delete []
 

When i create a char * string lets say, do i also have to then
remember to free up the memory after the program is done? Or is it
done automatically?

Is this right?

char * string = "Hello";

string = NULL;
free(string);

Re: char * string has to be free() or delete []
 

"zalzon" <zalzonishappy@zalll.com> wrote in message news:rs4li05nbopa8hsoiri7cgskjg70h1usep@4ax.com...
> When i create a char * string lets say, do i also have to then
> remember to free up the memory after the program is done? Or is it
> done automatically?
>
> Is this right?
>
> char * string = "Hello";
>
> string = NULL;
> free(string);

No, it is NOT right. char* isn't a string type. It's a pointer to a single char.
It is incumbent on you to remember how it was allocated. In the example
above, it's allocated to a statically allocated string literal. You don't call free
or delete on it.

If you alloc'd it with malloc you'd call free.
If you alloc a single character with new, you free it with delete.
If you alloc an array of char with new [], you free it with delete [].

Re: char * string has to be free() or delete []
 

So how would you free it in the above case then if not with free() ?

Re: char * string has to be free() or delete []
 

zalzon wrote:
> So how would you free it in the above case then if not with free() ?

You don't free it.

Re: char * string has to be free() or delete []
 

On Tue, 24 Aug 2004 03:37:41 GMT, Chris Dutton <rubyguru@hotmail.com>
wrote:

>zalzon wrote:
>> So how would you free it in the above case then if not with free() ?
>
>You don't free it.


Ah.

What happens to the pointer then?

I'm confused as to when you free and when not to free. I thought
anytime you create a pointer, you have to remember to free it.

Re: char * string has to be free() or delete []
 

zalzon wrote:
> On Tue, 24 Aug 2004 03:37:41 GMT, Chris Dutton <rubyguru@hotmail.com>
> wrote:
>
>
>>zalzon wrote:
>>
>>>So how would you free it in the above case then if not with free() ?
>>
>>You don't free it.
>
>
>
> Ah.
>
> What happens to the pointer then?
>
> I'm confused as to when you free and when not to free. I thought
> anytime you create a pointer, you have to remember to free it.

Any time you _dynamically allocate memory_ it must be freed.

[in your original example nothing is being dynamically allocated]

HTH,
--ag
--
Artie Gold -- Austin, Texas

20050120->44

Re: char * string has to be free() or delete []
 

On Mon, 23 Aug 2004 23:10:25 -0500, Artie Gold
<artiegold@austin.rr.com> wrote:

>Any time you _dynamically allocate memory_ it must be freed.

So anytime malloc is used, must remember to free.

Got ya.

Re: char * string has to be free() or delete []
 

Sorry one more question please.

If i malloc() memory to a char * string, do i then do this to free it?

string = NULL;
free(string);

Re: char * string has to be free() or delete []
 

zalzon wrote:
>
> Sorry one more question please.
>
> If i malloc() memory to a char * string, do i then do this to free it?
>
> string = NULL;
> free(string);
>
>

Yes.

malloc goes with free
calloc free
realloc free

new delete
new[] delete []

In C++ you usually use new/delete and not malloc/free.
You also don't allocate memory to a char* string, but
you use the std::string class.

--
Karl Heinz Buchegger
kbuchegg@gascad.at

Re: char * string has to be free() or delete []
 

zalzon wrote:

> Sorry one more question please.
>
> If i malloc() memory to a char * string, do i then do this to free it?
>
> string = NULL;
> free(string);

No. Well, yes, you have to free() it, but not the way you do. What
you're doing is first overwriting the pointer to your allocated memory
with a null pointer, then calling free on that null pointer. The
allocated memory is still existing, and you lost your pointer to it, so
you produced a memory leak. Just leave the "string = NULL;" line out.