Surprising binary messages!

5 is the surprising answer of the expression:
6 + 4 / 2

It should be 8
But, I got 5 in both 1.1 and 1.2.

Noury

There is no such priority in smalltalk. + / - * are just normal binary
messages - they take precedence over keyword messages and are second
in line after unary ones.

And everything is executed left to right so 5 is an expected answer here.

Regards,
Stanislav Paskalev



On Tue, Jan 18, 2011 at 1:29 PM, Noury Bouraqadi <[hidden email]> wrote:

Why should it be 8?

#+ and #/ have the same priority and they will be evaluated from left to right.

Cheers,
Doru


On 18 Jan 2011, at 12:29, Noury Bouraqadi wrote:

> 5 is the surprising answer of the expression:
> 6 + 4 / 2
>
> It should be 8
> But, I got 5 in both 1.1 and 1.2.
>
> Noury
>
>

--
www.tudorgirba.com

"The coherence of a trip is given by the clearness of the goal."

On Tue, Jan 18, 2011 at 12:29 PM, Noury Bouraqadi <[hidden email]> wrote:
> 5 is the surprising answer of the expression:
> 6 + 4 / 2
>
> It should be 8
> But, I got 5 in both 1.1 and 1.2.
>
> Noury
>

Hi,
I'm just starting to learn smalltalk (thanks to PbE), but I'm pretty
sure I know why this happens :-)

Smalltalk has no knowledge of mathematics order, just operation order.
In this case + and / are both binary operators so the operations are
evaluated with the usual order, from left to right:

(6 + 4) / 2

The answer 5 is correct.

Regards

Pietro

but this is normal. It was always like that. No operator precedence just messages

binary are evaluated from right to left
        6 + 4
                10 / 2
                        5
       

> 5 is the surprising answer of the expression:
> 6 + 4 / 2
>
> It should be 8
> But, I got 5 in both 1.1 and 1.2.
>
> Noury
>
>

On 18 January 2011 12:29, Noury Bouraqadi <[hidden email]> wrote:
> 5 is the surprising answer of the expression:
> 6 + 4 / 2
>
> It should be 8
> But, I got 5 in both 1.1 and 1.2.
>

this is first thing all smalltalkers learn: smalltalk syntax does not
using math operators precedence rules.
because #+ and #/ is just selectors and you can put any behavior to it
not nearly related to math.

> Noury
>
>
>



--
Best regards,
Igor Stasenko AKA sig.

>
> I'm just starting to learn smalltalk (thanks to PbE), but I'm pretty
> sure I know why this happens :-)

Excellent! I like that our energy helps people.

On Tue, Jan 18, 2011 at 12:40 PM, Stéphane Ducasse
<[hidden email]> wrote:
>>
>> I'm just starting to learn smalltalk (thanks to PbE), but I'm pretty
>> sure I know why this happens :-)
>
> Excellent! I like that our energy helps people.
>
It really does!

Thanks to all the Pharo/Squeak community for the great effort.

--
Pietro

6 + (4/2) will do what you want, for the reasons already well covered.

As an aside, have you ever really looked at the way mathematics is typeset in books?  Some of it does not bear close examination from a precedence/correctness perspective - missing parentheses, etc.  The problem was that I was trying to teach students that many of their mistakes would disappear if they could reliably read what they just wrote.




________________________________________
From: [hidden email] [[hidden email]] On Behalf Of Noury Bouraqadi [[hidden email]]
Sent: Tuesday, January 18, 2011 6:29 AM
To: [hidden email]
Subject: [Pharo-project] Surprising binary messages!

5 is the surprising answer of the expression:
6 + 4 / 2

It should be 8
But, I got 5 in both 1.1 and 1.2.

Noury

You're right. It looks like I need to sleep more :-D

Noury
On 18 janv. 2011, at 12:38, Stéphane Ducasse wrote:

Yes man.

Stef

> You're right. It looks like I need to sleep more :-D
>
> Noury