Drowning in Vectors

[The Hobo]

Okay. I just learned how to use vectors. And now I'm addicted. I have like 10 in my project right now, and I'm wondering if that's too many?

Do vectors use a lot of memory? Do they clean themselves up? Is there something special I should do to clean up the vectors at the end of my program.

Thanks.

[CornedBee]

They clean them up themselves. And they have only little overhead over the size of the data they actually contain. So unless it's just a hello world app 10 vectors is not too much.

But you should still think for every single vector: "Do I need this dynamic?". The vector class is really nice, but there's no excuse for using a vector for a static array.

[The Hobo]

The reason I'm using them to begin with is that I created a sub to make increase the size of a dynamic array, then posted it here to get feedback on how I was doing it, and the feedback was "use a vector."

I just happened to have 4 or 5 dynamic arrays and changed them to vectors.

So if I ask myself "do I really need this one?" I can't really answer unless I know that it's the best way to do it.

[jim mcnamara]

After the first instance of a class is declared & used the overhead is a lot less for each subsequent instance of the same class object.

So, ten is only too many if can't keep track of them or you really don't need them.

One of the things I do is to make existing code faster. As a side effect, it usually means way fewer lines of code. If you pass data back and forth between unnecessary variables it adds overhead as well as increasing complexity (probability of failure goes up).

It's your call

[CornedBee]

Nothing wrong with converting dynamic arrays to vectors. But do you need them dynamic?

How large is your project? If it's a real app you write alone (small to medium project size) 10 vectors is not much. If it's some uni assignment (tiny project size) 10 dynamic arrays should make you wonder if your approach to the problem is good.

[The Hobo]

Thanks, guys.

I'm pretty sure I need them dynamic. My program calls for the user to be able to enter stock info, and I want them to enter however many stocks they please, from 1 to however many stocks there are.

[jim mcnamara]

FWIW - the C99 standard supports dynamic arrays in a bass-ackwards way.

They are called variable length arrays.

void f(int dimension1, int dimension2){
       char whatever[dimension1][dimension2];
}

[Zaffir]

Maybe i should get around to learning more about C++, this stuff sounds kinda cool.

[The Hobo]

Originally posted by Zaffir
Maybe i should get around to learning more about C++, this stuff sounds kinda cool.

I just learned about them yesterday. They're pretty sweet.

[Zaei]

Originally posted by jim mcnamara
FWIW - the C99 standard supports dynamic arrays in a bass-ackwards way.

They are called variable length arrays.

void f(int dimension1, int dimension2){
       char whatever[dimension1][dimension2];
}

That is interesting, Jim. Thanks for the info!

Z.