Help-me

Ulf Wiger <>
Tue Apr 3 09:52:57 CEST 2001


On Tue, 3 Apr 2001, Raimo Niskanen wrote:

>Well,
>
>you can't do arrays in Erlang. Since Erlang is a functional
>programming language, mutable data structures (such as arrays) are
>not available in the language. The closest resembling data
>structures are ETS tables and the process dictionary. Both are
>accessed through BIFs (Built In Functions). The process dictionary
>can be quite a fast array if it is not too big.

For small arrays, you can use a tuple:

array(Size) -> erlang:make_tuple(Size).

read(Pos, Array) -> element(Pos, Array).

write(Pos, Array, Value) -> setelement(Pos, Array, Value).


But performance for write/3 will not be that great for bigger arrays.

On http://www.erlang.org, under "User Contributions", you can find
something called dynarray. It's a dynamically sized array-like
structure that works like the small example above.

Or, use ETS or process dictionary as Raimo suggests.


Perhaps you could clarify why you need a semaphore?


/Uffe
-- 
Ulf Wiger                                    tfn: +46  8 719 81 95
Senior System Architect                      mob: +46 70 519 81 95
Strategic Product & System Management    ATM Multiservice Networks
Data Backbone & Optical Services Division      Ericsson Telecom AB




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