Date: Mon, 28 Nov 1994 09:09:33 +0100
From: Thomas Eifert <EIFERT AT reze-1 DOT rz DOT rwth-aachen DOT de>
Subject: Re: Arrays vs. pointers
To: djgpp AT sun DOT soe DOT clarkson DOT edu
Reply-To: eifert AT rz DOT rwth-aachen DOT de
Organization: Rechenzentrum RWTH Aachen

> I was wondering what the exact differences betwen arrays and allocated pointers
> are.
> 
> If you have: 
> int array[big];
> 
> array[i] = 1;
> 
> or int * ptr
> ptr = new int[big];
> ptr[i] = 2;
> delete ptr
> 
> they both do about the same thing, but the first case makes your exe bigger.
> I would think that the first case can be alot faster however.  Is this correct?
> 
> Because if you are accessing an element, in the first case the compiler knows where
> it is.  It doesn't need to use a register for ptr and it doesn't even have to 
> dereference ptr. it can just add i to a constant number. to get the address.
> 
> Is this correct or have I completely lost it?
> 

The difference is the "dynamics":

The 2nd version does the same *after* the "new"-command, so the
allocation is done at run time, whereas in the 1st case the
allocation is done at compile time* !

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 | Thomas Eifert                                                    |
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