Dynamically Allocated Arrays

[ImpactDNI]

I'm working on a .ase loader for loading my models... I'm not all that great with C++, but im trying... Anyhow, i have read in an "int index", which is the number of verticies that are going to be read in next, I now need an array of array[index][3], for the x,y,z of each vertex.. Anyway, i dont know how to make it use "index" as a declarer for the size of the array...
Can anyone help me out on this? If you could, please post an example...
Thanks in Advance.
ImpactDNI

[31337]

There are two ways of managing dynamic memory, only one of which I can do effectively, its actually very easy. Look at the example below:

int x;
cin >> x;
char *data;
data = new char [x];
for(int i = 0; i<x; i++) {
data[i] = "A";
}
cout << data << endl;
delete data[];

The only line I'm not sure of being correct is the last one, being delete data[] but I'm 50% sure thats correct. Look up new and delete, they rule! Isn't that easy though?

[Deiussum]

Not to be picky, but it would actually be

delete [] data;

[31337]

how sure are you about that? don't the [] always come after the variable name? What's the sense in that?

Please explain, thanks a lot

[Deiussum]

I'm 100% sure of that.

delete and delete [] are different "operators."

You're right that the brackets always come after the variable name when defining the array, but the delete [] operator is a special case where they come first.

Part of the reason they did it that way I think, was because if you have something like so...

char** ppChArray = new char*[10];
for (int c=0;c<10;c++) ppChArray[c] = new char[10];

// now delete
for (int c=0;c<10;c++)
{
delete [] ppChArray[c]; // seems cleaner somehow than delete ppChArray[c][]
}

delete [] ppChArray;



[This message has been edited by Deiussum (edited 11-22-2002).]

[31337]

Yah I guess your right. So what do you do when you wanto delete one of the dimensions of the array x[y]? Is it delete [] x[]?

[ImpactDNI]

WOW!!! lol, thats so helpful, i love this board, you guys rock! I've seen the new and delete commands, but never used them... again, this helps a ton, and you guys rule, (im out of school for the weekend) but if i have any more trouble getting this to work, ill be sure to post back!
Thanks again!
ImpactDNI

[Deiussum]

Originally posted by 31337:
Yah I guess your right. So what do you do when you wanto delete one of the dimensions of the array x[y]? Is it delete [] x[]?

You'd have to know which element you want to delete. It would be

delete [] x[nIndexToDelete];

[jebus]

and remember, if you have an array:

buf[x]

and you use this:

delete buf;

without the [], this will only delete the first entry in the array.

jebus

[Bob]

Using delete on an array allocated with new[] is undefined behaviour. Most compilers I know of will release the whole memory block though, but don't count on it working properly.