RE: [Dev-C++] dynamic allocation and structs

[Scott W. <se...@al...>]

Don't know if anyone responded yet but I think the answer is: Yes, unless
your OS messes up.  The release of the memory wasn't actually my concern,
however, I just wanted to be sure memory I allocated in one part of my
program was going to be available elsewhere.

Scott

-----Original Message-----
From: Louis Godio [mailto:lg...@ya...]
Sent: Friday, October 25, 2002 8:30 PM
To: se...@al...; Per Westermark
Cc: dev...@li...
Subject: RE: [Dev-C++] dynamic allocation and structs

What was the final answer to the the original question asked:
"what is the duration of memory allocated by malloc (etc.)? "

If not freed manually or by a destructor, Does the memory ALWAYS get
released when the main() program ends with a normal exit  ?

--- Scott Williams <se...@al...> wrote:
> Thanks for the replies to my question (and the entertaining
> discussion it led to).  It was all very helpful.
>
> Scott
>
> -----Original Message-----
> From: Per Westermark [mailto:pw...@ia...]
> Sent: Thursday, October 24, 2002 9:13 AM
> To: Scott Williams
> Cc: dev...@li...
> Subject: Re: [Dev-C++] dynamic allocation and structs
>
> // Alternative 1, array of entries.
> mystruct *myarray;
> void func(int count) {
>     int i;
>     myarray = (mystruct*)malloc(count*sizeof(mystruct));
>     for (i = 0; i < count; i++) {
>         myarray[i].xx = yy;
>     }
> }
>
> // Alternative 2, array of pointers to entries.
> mystruct **myarray;
> void func(int count) {
>     int i;
>     myarray = (mystruct**)malloc(count*sizeof(*mystruct));
>     for (i = 0; i < count; i++) {
>         myarray[i] = (mystruct*)malloc(sizeof(mystruct));
>         myarray[i]->xx = yy;
>     }
> }
>
> /Per W
>
> On Thu, 24 Oct 2002, Scott Williams wrote:
>
>> Hi,
>>
>> I'm working in C (no C++ please).  Got a couple of questions
>> related to dynamic allocation and in particular, dynamically
>> allocating an array of structs.
>>
>> First, what is the duration of memory allocated by malloc
>> (etc.)?  In particular, I want to dynamically allocate/de-
>> allocate several global variables within a single subroutine
>> called from main and so want to be sure that the allocated
>> memory exists beyond the scope of that subroutine.
>>
>> Second, it is my understanding that it is perfectly acceptable
>> to have an array of structs.  E.g.,
>>
>> struct mystruct {
>>   double var1;
>>   long   var2;
>>   etc...
>> }
>>
>> . . .
>>
>> struct mystruct data[100];
>>
>> Is this correct?  If so, what then is the calling sequence to
>> dynamically allocate an array of structs, and, in particularly,
>> make the result available globally?
>>
>> Thanks for your help (& sorry if this is naive).
>>
>> Scott Williams