Re: array question

Re: array question

[bill]

In article <78189o$2bj@eng-ser1.erg.cuhk.edu.hk>, ycli6@se.cuhk.edu.hk says...
 
>	i want to ask a question in array.
>type MY_ARRAY is array(INTEGER range <>) of FLOAT;
>
>what is the meaning of <>, also can i replace INTEGER with
>other type? such as FLOAT, BOOLEAN?
>

<> means the range is undertmined at type declaration time.
when you then define a variable this type, then you need to specify
the range. This way you can use the same type to define different
objects of that type of varying ranges. so you dont have to have
to declare a new type everytime where is the only difference
between them is the value of the range. this is called generic type.

yes, you can change INTEGER above. this is the type of the index. which
can be any scalar type.

check some of the Ada text books for examples.

bill
 

array question

[yukchi]

hihi,
	i want to ask a question in array.
type MY_ARRAY is array(INTEGER range <>) of FLOAT;

what is the meaning of <>, also can i replace INTEGER with
other type? such as FLOAT, BOOLEAN?

Thanks!

--
****    ****  **    **  **      ** **     ** **   **     ** ** **
****   ****** ***  ***   **    **  **     ** **  **      ** ** **
 **    **  ** ********    **  **   **     ** ** **       ** ** **
 **    ****** ********     ****    **     ** ****        ** ** **
 **    ****** ** ** **      **     **     ** ** **       ** ** **
 **    **  ** **    **      **     **     ** **  **      
****   **  ** **    **      **     ********* **   **     ** ** **
****   **  ** **    **      **       *****   **    **    ** ** **

Re: array question

[Matthew Heaney]

ycli6@se.cuhk.edu.hk (yukchi) writes:

> hihi,
> 	i want to ask a question in array.
> type MY_ARRAY is array(INTEGER range <>) of FLOAT;
> 
> what is the meaning of <>, also can i replace INTEGER with
> other type? such as FLOAT, BOOLEAN?
> 
> Thanks!
> 
> --
> ****    ****  **    **  **      ** **     ** **   **     ** ** **
> ****   ****** ***  ***   **    **  **     ** **  **      ** ** **
>  **    **  ** ********    **  **   **     ** ** **       ** ** **
>  **    ****** ********     ****    **     ** ****        ** ** **
>  **    ****** ** ** **      **     **     ** ** **       ** ** **
>  **    **  ** **    **      **     **     ** **  **      
> ****   **  ** **    **      **     ********* **   **     ** ** **
> ****   **  ** **    **      **       *****   **    **    ** ** **

Yes, you are Yuk.  Please get rid of this signature.  It is very
annoying.

The "<>" is refered to as "box."  It means that information has been
omitted.  Here, in your array declaration, it means that you are omitted
index constraints in the type.

Objects of that type can have any index constraints:

procedure Op (X : in My_Array) is
begin
   ... X'First can be any value in type Integer
   ... X'Last can be any value in type Integer

However, compare that with

subtype Matts_Array is My_Array (1 .. 10);

Now we have declared a subtype that constrains the index of the base
type My_Array.  We could do something similar using a completely
different type:

type Matts_Array is array (Integer range 1 .. 10) of Float;

Objects of (sub)type Matts_Array all have index values such that X'First
is 1, and X'Last is 10.

An array can be indexed by any discrete type (integer types or
enumeration types).  That means Float is not acceptable, becuase that
type is a floating point type, not a discrete type.  However, Boolean is
acceptable, becuase it is a discrete type.

Please get rid of your annoying signiture.

Re: array question

[David C. Hoos, Sr.]

bill@nospam.com wrote in message <7819qk$cbj@drn.newsguy.com>...
>In article <78189o$2bj@eng-ser1.erg.cuhk.edu.hk>, ycli6@se.cuhk.edu.hk
says...
>
>> i want to ask a question in array.
>>type MY_ARRAY is array(INTEGER range <>) of FLOAT;
>>
>>what is the meaning of <>, also can i replace INTEGER with
>>other type? such as FLOAT, BOOLEAN?
>>
>
><> means the range is undertmined at type declaration time.
>when you then define a variable this type, then you need to specify
>the range. This way you can use the same type to define different
>objects of that type of varying ranges. so you dont have to have
>to declare a new type everytime where is the only difference
>between them is the value of the range. this is called generic type.
>

This is not correct.  Such a type is called an _unconstrained_
array type.

>yes, you can change INTEGER above. this is the type of the index. which
>can be any scalar type.


This is wrong.  Array indices can be of any _discrete_ type.  This
means that the real scalar types are _excluded_

>
>check some of the Ada text books for examples.
>
>bill
>

Re: array question

[Tom Moran]

>	i want to ask a question in array.
>type MY_ARRAY is array(INTEGER range <>) of FLOAT;

>what is the meaning of <>, 
  It's indefinite - array of this type can have various lengths, eg
short : my_array(1 .. 10);
long : my_array(1 .. 10000);
   If you said instead
type my_other_array is array(integer range 1 .. 50) of float;
  then you could say
x : my_other_array;
y: my_other_array;
  but you couldn't say
z : my_other_array(1 .. 10);
  since my_other_array type was defined with fixed bounds of 1 .. 50

>also can i replace INTEGER with
>other type? such as FLOAT, BOOLEAN?
  Boolean yes, Float no.  (How would you go about setting the initial
values of an array(float range 0.1 .. 0.2)?  x(0.100000001) := 1;
x(0.100000002) := 2; etc?)  

Re: array question

[Bryan Shayne]

<> means undefined.  You must define a constraint before actual usage
though.

yukchi wrote:

> hihi,
>         i want to ask a question in array.
> type MY_ARRAY is array(INTEGER range <>) of FLOAT;
>
> what is the meaning of <>, also can i replace INTEGER with
> other type? such as FLOAT, BOOLEAN?
>
> Thanks!
>
> --
> ****    ****  **    **  **      ** **     ** **   **     ** ** **
> ****   ****** ***  ***   **    **  **     ** **  **      ** ** **
>  **    **  ** ********    **  **   **     ** ** **       ** ** **
>  **    ****** ********     ****    **     ** ****        ** ** **
>  **    ****** ** ** **      **     **     ** ** **       ** ** **
>  **    **  ** **    **      **     **     ** **  **
> ****   **  ** **    **      **     ********* **   **     ** ** **
> ****   **  ** **    **      **       *****   **    **    ** ** **

array question

[agent]

I would like to define a array that can use a character as its index. 
type FSATyp is (Delim, Op, Dgt, AllElse);

FsaArray : ARRAY Character range ('' .. Character'Val(255)) OF FSATyp;

I'm getting an error saying that I'm missing '(' and extra ')' is
ignored.  It is also saying missing => and that strings are delimited
by double quotes.

I'm sure what I want is possible, but I seem to have the syntax wrong.

Any help would be appreciated.

Re: array question

[Jeffrey Carter]

On 02/09/2014 08:49 PM, agent@drrob1.com wrote:
> I would like to define a array that can use a character as its index.
> type FSATyp is (Delim, Op, Dgt, AllElse);
>
> FsaArray : ARRAY Character range ('' .. Character'Val(255)) OF FSATyp;

The syntax for an array definition is given in ARM 3.6 
(http://www.adaic.org/resources/add_content/standards/12rm/html/RM-3-6.html).

-- 
Jeff Carter
"I've got to stay here, but there's no reason
why you folks shouldn't go out into the lobby
until this thing blows over."
Horse Feathers
50

Re: array question

[agent]

On Sun, 09 Feb 2014 22:39:06 -0700, Jeffrey Carter
<spam.jrcarter.not@spam.not.acm.org> wrote:

>On 02/09/2014 08:49 PM, agent@drrob1.com wrote:
>> I would like to define a array that can use a character as its index.
>> type FSATyp is (Delim, Op, Dgt, AllElse);
>>
>> FsaArray : ARRAY Character range ('' .. Character'Val(255)) OF FSATyp;
>
>The syntax for an array definition is given in ARM 3.6 
>(http://www.adaic.org/resources/add_content/standards/12rm/html/RM-3-6.html).

Thanks

Re: array question

[Mike H]

In message <2migf9h07j7ll0eqk7oh3e64m1e0lv3r5r@4ax.com>, 
agent@drrob1.com writes
>I would like to define a array that can use a character as its index.
>type FSATyp is (Delim, Op, Dgt, AllElse);
>
>FsaArray : ARRAY Character range ('' .. Character'Val(255)) OF FSATyp;
>
type FsaArray_type is array (ASCII.nul .. ASCII.del) of FSATyp;
FsaArray : FsaArray_type := (others => ASCII.nul);
-- 
The thing I like best about the Internet is that no one
knows that, in reality, I am just another old dog!
Mike

Re: array question

[Mike H]

In message <5aOMAcEhbN+SFw0R@ada-augusta.demon.co.uk>, Mike H 
<postmaster@ada-augusta.demon.co.uk> writes
>type FsaArray_type is array (ASCII.nul .. ASCII.del) of FSATyp;
>FsaArray : FsaArray_type := (others => ASCII.nul);
Whoops! An 80-year-old dog who is slipping into dementia?
-- 
The thing I like best about the Internet is that no one
knows that, in reality, I am just another old dog!
Mike

Re: array question

[Robert A Duff]

Mike H <postmaster@ada-augusta.demon.co.uk> writes:

> In message <5aOMAcEhbN+SFw0R@ada-augusta.demon.co.uk>, Mike H
> <postmaster@ada-augusta.demon.co.uk> writes
>>type FsaArray_type is array (ASCII.nul .. ASCII.del) of FSATyp;
>>FsaArray : FsaArray_type := (others => ASCII.nul);
> Whoops! An 80-year-old dog who is slipping into dementia?

;-)

How about:

type FsaArray_type is array (Character) of FSATyp;

?

- Bob

Re: array question

[Mike H]

In message <wcck3d2ex7y.fsf@shell01.TheWorld.com>, Robert A Duff 
<bobduff@shell01.TheWorld.com> writes
>Mike H <postmaster@ada-augusta.demon.co.uk> writes:
>
>> In message <5aOMAcEhbN+SFw0R@ada-augusta.demon.co.uk>, Mike H
>> <postmaster@ada-augusta.demon.co.uk> writes
>>>type FsaArray_type is array (ASCII.nul .. ASCII.del) of FSATyp;
>>>FsaArray : FsaArray_type := (others => ASCII.nul);
>> Whoops! An 80-year-old dog who is slipping into dementia?
>
>;-)
>
>How about:
>
>type FsaArray_type is array (Character) of FSATyp;
Looks good to me! It is my second line that is rubbish. It should be ...
FsaArray : FsaArray_type;
My personal dislike of uninitialised variables tripped me up.

-- 
"Why," said Ford squatting down beside him and shivering, "are you lying face
down in the dust?" "It's a very effective way of being wretched," said Marvin.
Mike ;-(

Re: array question

[Dennis Lee Bieber]

On Mon, 10 Feb 2014 15:13:57 +0000, Mike H
<postmaster@ada-augusta.demon.co.uk> declaimed the following:

>In message <5aOMAcEhbN+SFw0R@ada-augusta.demon.co.uk>, Mike H 
><postmaster@ada-augusta.demon.co.uk> writes
>>type FsaArray_type is array (ASCII.nul .. ASCII.del) of FSATyp;
>>FsaArray : FsaArray_type := (others => ASCII.nul);
>Whoops! An 80-year-old dog who is slipping into dementia?

	Say it isn't so... You're scaring this 55 year old Vargr

-- 
	Wulfraed                 Dennis Lee Bieber         AF6VN
    wlfraed@ix.netcom.com    HTTP://wlfraed.home.netcom.com/

Re: array question

[Mike H]

Dennis Lee Bieber writes...
>       Say it isn't so... You're scaring this 55 year old Vargr
Oh Dear! You have another 25 years to go before your age becomes 
something to boast about!

-- 
"Life is not a journey to the grave with the intention of arriving safely
in a well preserved body, but rather to skid in broadside, thoroughly used up,
totally worn out and loudly proclaiming; WOW!!! What a ride."
Mike ;-)

Re: array question

[agent]

On Mon, 10 Feb 2014 11:41:53 -0500, Robert A Duff
<bobduff@shell01.TheWorld.com> wrote:

>Mike H <postmaster@ada-augusta.demon.co.uk> writes:
>
>> In message <5aOMAcEhbN+SFw0R@ada-augusta.demon.co.uk>, Mike H
>> <postmaster@ada-augusta.demon.co.uk> writes
>>>type FsaArray_type is array (ASCII.nul .. ASCII.del) of FSATyp;
>>>FsaArray : FsaArray_type := (others => ASCII.nul);
>> Whoops! An 80-year-old dog who is slipping into dementia?
>
>;-)
>
>How about:
>
>type FsaArray_type is array (Character) of FSATyp;
>
>?
>
>- Bob

How simple and elegent.  And it worked for me.

Thanks.

Re: array question

[Mike H]

In message <qp8lf9p2a6gpnrhkcd5b342mgpg6ftgob7@4ax.com>, 
agent@drrob1.com writes
>
>How simple and elegent.  And it worked for me.
>
Welcome to the friendly fields of Ada-land!
-- 
"Whom the gods would destroy, they first invite to program in C"
Mike