Thread: how to double an array size?

well this is the code i got going:

Code:

string *temparray = new string[max_size*2];
for(int i = 0; i < max_size; i++
{
temparray[i] = sentence[i];
}
delete[] sentence;
sentence = temparray;
delete[] temparray;
max_size = max_size*2;

the code is set to a function so it can be called more than once.

So, why delete[] temparray? You still need it, after all, since that's where everything is. Once you do sentence = temparray, the two are forever joined (that is, they currently point at the same piece of memory) and so deleting one will in fact delete both.

well the function is part of a class and sentence is a private data

Originally Posted by dotz02x

well the function is part of a class and sentence is a private data

You say that as though that is in any way relevant.

but dont i have to deallocate all memory that has been allocated? or can i do that at the end of my program?

You are misunderstand though.

Example

Code:

int *x, *y;

x = new int[5];
y = x;

delete[] y;

Does that illustrate tabstop's point more clearly? A pointer is referring to data at a given address. Think of it as if I told you where the mall is. Then I get hit by a bus. The knowledge of where the mall exists still exists through you regardless of my state.

So as seen above, deleting y also deletes x.

Originally Posted by dotz02x

but dont i have to deallocate all memory that has been allocated? or can i do that at the end of my program?

At some point, yes. This should be a function that returns temparray.

well okay i figured out that problem but... i have another problem and that is now my sentence array contains no data because the function is in the private section of a class.

If i copy the array over instead of setting sentence to point to temparray will this work?

when i try to cout << sentence[i]; in a loop to output each of the words for some reason it displays nothing now....

And where do you do that? Since sentence is private, it can _only_ be accessed by member functions. If you are in a member function, then post your code so we have some idea what you're talking about.

Attempting to access private data outside of a class definition would produce a compile error.