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comp.lang.ruby

what's wrong in my loop ?

Josselin

10/2/2006 12:19:00 PM

I wrote the following loop some records ,

init an array db
get a record , loop on all records indexing by i
while record.start_at <= record.end_at
put in the db array [record.start_at, i]
end while
loop on records
end


but it seems that's Ruby doesn't like it .. what's wrong ? is theer any
way to write it better ?

db = []
record.each do |b|
aDate = b.start_at
i = 0
while aDate <= b.end_at
db << [ aDate, i ]
i++
aDate= aDate + i
end
end

jossss
4 Answers

Tom Armitage

10/2/2006 12:26:00 PM

0

I think you might find it's the "i++".

Try "i.next" or "i += 1"

t.

On 02/10/06, Josselin <josselin@wanadoo.fr> wrote:
> I wrote the following loop some records ,
>
> init an array db
> get a record , loop on all records indexing by i
> while record.start_at <= record.end_at
> put in the db array [record.start_at, i]
> end while
> loop on records
> end
>
>
> but it seems that's Ruby doesn't like it .. what's wrong ? is theer any
> way to write it better ?
>
> db = []
> record.each do |b|
> aDate = b.start_at
> i = 0
> while aDate <= b.end_at
> db << [ aDate, i ]
> i++
> aDate= aDate + i
> end
> end
>
> jossss
>
>
>

Stephane Elie

10/2/2006 12:55:00 PM

0

Hi Josselin,

Tom is right about the "i++".

Also, it doesn't look like your pseudo-code matches your ruby code
functionality.

I'll give it a shot as what you may want to do, just a guess...

db = []
record.each do |b|
(b.end_at - b.start_at).times { |i| db << [b.start_at+i, i ] }
end


--
Posted via http://www.ruby-....

Josselin

10/2/2006 5:01:00 PM

0

On 2006-10-02 14:54:58 +0200, Stephane Elie <stephane.elie@gmail.com> said:

> Hi Josselin,
>
> Tom is right about the "i++".
>
> Also, it doesn't look like your pseudo-code matches your ruby code
> functionality.
>
> I'll give it a shot as what you may want to do, just a guess...
>
> db = []
> record.each do |b|
> (b.end_at - b.start_at).times { |i| db << [b.start_at+i, i ] }
> end

thansk Tom & Steph
newbie I am mixin any languages into it....
I actually need to remember first that Ruby is OO, so i.next makes more
sense compared to i++

joss

Rick DeNatale

10/2/2006 10:03:00 PM

0

On 10/2/06, Josselin <josselin@wanadoo.fr> wrote:
> On 2006-10-02 14:54:58 +0200, Stephane Elie <stephane.elie@gmail.com> said:
>
> > Hi Josselin,
> >
> > Tom is right about the "i++".
> >
> > Also, it doesn't look like your pseudo-code matches your ruby code
> > functionality.
> >
> > I'll give it a shot as what you may want to do, just a guess...
> >
> > db = []
> > record.each do |b|
> > (b.end_at - b.start_at).times { |i| db << [b.start_at+i, i ] }
> > end
>
> thansk Tom & Steph
> newbie I am mixin any languages into it....
> I actually need to remember first that Ruby is OO, so i.next makes more
> sense compared to i++

The expression i++ isn't valid ruby.

Keep in mind that

i.next

all by itself has no effect on i:

i = 2
p i.next => 3
p i => 2

Don't confuse the variable i with the object it contains. The
expression i++ simply asks the object 2 for it's successor leaving it
unchanged.

i += 1

which is the same as:

i = i + 1

computes the value of i + 1 and assigns the result to the variable i.

you could also use

i = i.next


--
Rick DeNatale

My blog on Ruby
http://talklikeaduck.denh...