Ivan Senji wrote:

> "Stewart Gordon" <smjg_1998@yahoo.com> wrote in message
> news:c7d6dp$1o8d$1@digitaldaemon.com...
<snip>
>>Not _the_ expression, but _an_ expression.  That expression is b[i],
>>where b remains the _result_ of the expression in the code.
> 
> I'm sorry but my English is not that great and i didn't undesrtand what
> areyou trying
> to say.

Maybe that wasn't the best way of putting it.

Suppose you have a function that returns an array.  Then you could do

	qwert[] = yuiop();

or equivalently

	qwert[] = yuiop()[];

The function yuiop is evaluated once.  Each element of the result is then taken and put into the corresponding element of qwert.

Similarly, with arithmetic

	c[] = a[] + b[];

the addition is done once across the array, and then the array elements are put into c.

In fact, these are all equivalent:

	c[] = a + b;
	c[] = a[] + b;
	c[] = a + b[];
	c[] = a[] + b[];
	c[] = (a + b)[];

> It would be nice if there was a syntax to ensure that the expression on the
> right is
> evaluated every time.
> 
> For example
> int[] x = new int[30];
> int i=0;
> x[!] = i++;
> 
> This would fill x with numbers form 0 to 29 what isn't currently possible
> this easy.

I'm not sure about this.  One might look at this and think "this isn't in a loop, so i will be incremented once".  Especially before they've discovered what [!] means.  Rewriting the left-hand side to change the behaviour of the right-hand side seems a little odd.  Moreover, if the assignment is in the middle of an expression, or you have [!]s chained together, it could get really confusing.

> I was also thinking (when we get array operations one day) that it would be
> great to have access to the index used in for.
> 
> i could then write
> x[] = index(0) * 3;
> filling x with 0, 3,6...

Hmm ... I don't know how tricky such a feature would be.

> another thing i tried to do today is:
> int[][][] x;
> x = new int[][][10];
> x[] = new int[][30];  //this doesn't work the expected way
> // maybe x[!] = new int[][30];
> 
> but this isn't even possible:
> 
> x[][] = new int[15]; // x[!][!] = new int[15]; would also be nice

I don't know if something like

	x = new int[15][20][30];

would work.  Maybe I'll try it when I get home....

<snip>
> But if we could do even:
> x[!][!][!] = index(0)+index(1)+index(2);
> 
> that would be a very easy way to fill arrays with some pattern.
<snip>

Maybe there are some APL hackers around, who'd like to be able to just about anything with a one-liner....

Stewart.

-- 
My e-mail is valid but not my primary mailbox, aside from its being the unfortunate victim of intensive mail-bombing at the moment.  Please keep replies on the 'group where everyone may benefit.

"Vathix" <vathixSpamFix@dprogramming.com> wrote in message news:c7dq7l$2qt9$1@digitaldaemon.com...
> In article <c7dp1g$2pv9$1@digitaldaemon.com>, ivan.senji@public.srce.hr
says...
> >
> >Here goes another strange thing.
> >int[][][] x = new int[][][10];
> >x[] = new int[][20]; //but not with the expected meaning.
> >x[][] = new int[][21]; //possible
> >x[][][] = new int[][22]; //also possible
> >x[][][][] = new int[][23]; //still possible...
> >
> >type of x is int[][][]
> >type of x[]is int[][]
> >type of x[][] is int[][]
> >type of x[][][] is int[][]
> >
> >
>
> x[] is shorthand for x[0 .. x.length].
> So there's nothing wrong with x[0 .. x.length][0 .. x.length][0 ..
x.length]
> nor with x[][][]. It's just re-slicing the same memory.

Makes sence! Thanks. But it would be nice to have moredimensional slices.

>
>
> --
> Christopher E. Miller
>

"Stewart Gordon" <smjg_1998@yahoo.com> wrote in message news:c7e1kp$5d5$1@digitaldaemon.com...
> Ivan Senji wrote:
>
> > "Stewart Gordon" <smjg_1998@yahoo.com> wrote in message news:c7d6dp$1o8d$1@digitaldaemon.com...
> <snip>
> >>Not _the_ expression, but _an_ expression.  That expression is b[i], where b remains the _result_ of the expression in the code.
> >
> > I'm sorry but my English is not that great and i didn't undesrtand what
> > areyou trying
> > to say.
>
> Maybe that wasn't the best way of putting it.
>
> Suppose you have a function that returns an array.  Then you could do
>
> qwert[] = yuiop();
>
> or equivalently
>
> qwert[] = yuiop()[];
>
> The function yuiop is evaluated once.  Each element of the result is then taken and put into the corresponding element of qwert.
>
> Similarly, with arithmetic
>
> c[] = a[] + b[];
>
> the addition is done once across the array, and then the array elements are put into c.
>
> In fact, these are all equivalent:
>
> c[] = a + b;
> c[] = a[] + b;
> c[] = a + b[];
> c[] = a[] + b[];
> c[] = (a + b)[];
>
> > It would be nice if there was a syntax to ensure that the expression on
the
> > right is
> > evaluated every time.
> >
> > For example
> > int[] x = new int[30];
> > int i=0;
> > x[!] = i++;
> >
> > This would fill x with numbers form 0 to 29 what isn't currently
possible
> > this easy.
>
> I'm not sure about this.  One might look at this and think "this isn't in a loop, so i will be incremented once".  Especially before they've discovered what [!] means.  Rewriting the left-hand side to change the behaviour of the right-hand side seems a little odd.  Moreover, if the assignment is in the middle of an expression, or you have [!]s chained together, it could get really confusing.

You are probbably right. It is good to ask stupid question because that way you can get good answers :)


> > I was also thinking (when we get array operations one day) that it would
be
> > great to have access to the index used in for.
> >
> > i could then write
> > x[] = index(0) * 3;
> > filling x with 0, 3,6...
>
> Hmm ... I don't know how tricky such a feature would be.
>
> > another thing i tried to do today is:
> > int[][][] x;
> > x = new int[][][10];
> > x[] = new int[][30];  //this doesn't work the expected way
> > // maybe x[!] = new int[][30];
> >
> > but this isn't even possible:
> >
> > x[][] = new int[15]; // x[!][!] = new int[15]; would also be nice
>
> I don't know if something like
>
> x = new int[15][20][30];
>
> would work.  Maybe I'll try it when I get home....

This won't work. The most you can do is x = new int[][][30];
I tried it also in c# where it is also imposible for jagged arrays
but is possible for rectangular arrays.

> <snip>
> > But if we could do even:
> > x[!][!][!] = index(0)+index(1)+index(2);
> >
> > that would be a very easy way to fill arrays with some pattern.
> <snip>
>
> Maybe there are some APL hackers around, who'd like to be able to just about anything with a one-liner....
>
> Stewart.
>
> --
> My e-mail is valid but not my primary mailbox, aside from its being the unfortunate victim of intensive mail-bombing at the moment.  Please keep replies on the 'group where everyone may benefit.