Hi everybody!
Just wondering if it is possible to point to variables in the heap.
For example, is this okay?
int * ptr_to_DAIA; // pointer to dynamically allocated integer array
ptr_to_DAIA = new int [SIZE];
for(i=0; i<SIZE; i++) ptr_to_DAIA[i]=i;
// now say I want a pointer that points to the element that contains
value TARGET
int * ptr_to_elem_in_ DAIA; // pointer to element in DAIA
for(i=0; i<SIZE; i++) if(ptr_to_DAIA[i]=TARGET)
ptr_to_elem_in_ DAIA=&ptr_to_DA IA[i];
In other words, other than the whole bare pointer=bad issue, will this
code be stable? Will ptr_to_elem_in_ DAIA always point to the right
place in the heap? Are there any subtle issues I should worry about
here?
Thanx.
2  1377  so******@gmail. com wrote: Hi everybody!
Just wondering if it is possible to point to variables in the heap.
It seems that by "heap", you mean the free store. "heap" has a different
meaning in C++. And there are no variables on the free store, since a
variable has a name and dynamically allocated objects don't.
For example, is this okay?
int * ptr_to_DAIA; // pointer to dynamically allocated integer array
ptr_to_DAIA = new int [SIZE];
for(i=0; i<SIZE; i++) ptr_to_DAIA[i]=i;
// now say I want a pointer that points to the element that contains
value TARGET
int * ptr_to_elem_in_ DAIA; // pointer to element in DAIA
for(i=0; i<SIZE; i++) if(ptr_to_DAIA[i]=TARGET)
This is an assignment, not a comparison, which seems to be what you really
wanted.
ptr_to_elem_in_ DAIA=&ptr_to_DA IA[i];
In other words, other than the whole bare pointer=bad issue, will this
code be stable? Will ptr_to_elem_in_ DAIA always point to the right
place in the heap?
No. If there is no element with the same value as TARGET in the array,
ptr_to_elem_in_ DAIA will be uninitialized. But other than that, it's ok.
Btw, I'd use the standard find algorithm for this:
ptr_to_elem_in_ DAIA = std::find(ptr_t o_DAIA, ptr_to_DAIA + SIZE, TARGET);
On 2005-06-14 15:25:54 -0400, so******@gmail. com said: Hi everybody!
Just wondering if it is possible to point to variables in the heap.
For example, is this okay?
int * ptr_to_DAIA; // pointer to dynamically allocated integer array
ptr_to_DAIA = new int [SIZE];
for(i=0; i<SIZE; i++) ptr_to_DAIA[i]=i;
// now say I want a pointer that points to the element that contains
value TARGET
int * ptr_to_elem_in_ DAIA; // pointer to element in DAIA
for(i=0; i<SIZE; i++) if(ptr_to_DAIA[i]=TARGET)
ptr_to_elem_in_ DAIA=&ptr_to_DA IA[i];
In other words, other than the whole bare pointer=bad issue, will this
code be stable?
Yes, at least until ptr_to_DAIA is delete'd (and assuming that TARGET
was actually found between ptr_to_DAIA and ptr_to_DAIA+SIZ E).
Your code/question essentially boils down to:
int *ptr = new int[SIZE];
int *ptr2 = ptr + (some integer between zero and SIZE);
If that didn't work, the entire language would fall apart :)
--
Clark S. Cox, III cl*******@gmail .com This thread has been closed and replies have been disabled. Please start a new discussion. Similar topics | |
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