I don't know how to post the output of irb so I'll just have to describe
it but if I run the following code:
0.upto(10){ |i| puts i }
...I will get 11 lines of output. This iterates eleven times. Really?!
Why it does this is obvious. Integer.upto is inclusive so it includes
both 0 and 10. However, am I the only one who thinks this is strange
behaviour? I mean, the ususal programming protocol is that the last element
is not included (half-open sets, if you will) so the number of iterations is
the difference between numbers.
Why did Ruby turn out this way? Thank you...
Just Another Victim of the Ambient Morality wrote:
0.upto(10){ |i| puts i }
...I will get 11 lines of output
Because 0 to 10 is 11 numbers. If you want 10 numbers, use 1.upto(10)
If you want different behavior, you can use a different looping method,
or use post or pre increment, depending if you want it to display the
last element or not.
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Why it does this is obvious. Integer.upto is inclusive so it includes
both 0 and 10. However, am I the only one who thinks this is strange
behaviour? I mean, the ususal programming protocol is that the last element
is not included (half-open sets, if you will) so the number of iterations is
the difference between numbers.
Why did Ruby turn out this way? Thank you...
It isn't really that Ruby is this way just that the method 'upto' is this way.
There are several other ways to iterate over an integer range:
>> (0..4).each { |i| puts i }
0
1
2
3
4
>> (0...4).each { |i| puts i }
0
1
2
3
>> 4.times { |i| puts i }
0
1
2
3
>> 0.step(4).each { |i| puts i }
0
1
2
3
4
>> 0.step(4,2).each { |i| puts i }
0
2
4
···
On Dec 23, 2008, at 2:36 PM, Just Another Victim of the Ambient Morality wrote:
"Just Another Victim of the Ambient Morality" <ihatespam@hotmail.com> wrote
in message news:xab4l.3997$9i5.3385@en-nntp-07.dc1.easynews.com...
I don't know how to post the output of irb so I'll just have to
describe it but if I run the following code:
0.upto(10){ |i| puts i }
...I will get 11 lines of output. This iterates eleven times.
Really?!
Why it does this is obvious. Integer.upto is inclusive so it includes
both 0 and 10. However, am I the only one who thinks this is strange
behaviour? I mean, the ususal programming protocol is that the last
element is not included (half-open sets, if you will) so the number of
iterations is the difference between numbers.
Why did Ruby turn out this way? Thank you...
D'oh!
...and by ".upto" I, of course, meant ".step" !
I don't know how to post the output of irb so I'll just have to describe
it but if I run the following code:
0.upto(10){ |i| puts i }
...I will get 11 lines of output. This iterates eleven times. Really?!
because this are eleven numbers: 0 1 2 3 4 5 6 7 8 9 10
Why it does this is obvious. Integer.upto is inclusive so it includes
both 0 and 10. However, am I the only one who thinks this is strange
behaviour?
why do you think a loop from 0 to 10 should exclude the upper border?
In Ada it is 'for i in 0 .. 10 loop' which is a loop from 0 to 10.
-Thomas
To show my age I can say that FORTRAN is inclusive to:
DO 100 I = 0,10
...
100 CONTINUE
executes 11 times.
Many languages I know don't have looping structures of this sort but have explicit initialization, test, post loop action things (e.g. C/C++ for loops). There it's idiomatic to write e.g.:
for(i =0; i < 10; i++) {..}
since int array[10] has elements 0..9, however it's certainly not required as
for(i =0; i<=10; i++){...}
is certainly just fine... if that's what's intended.
I go back to my mantra when using a language I'm new to. The mantra is based on a 'game' model of programming languages... languages are games, they have rules. The rules may have reasons, or they may be arbitrary choices. They may even be capricious in some languages (e.g. LOLCODE see http://www.globalnerdy.com/2007/05/28/lolcode-the-lolcat-programming-language/\).
But if you don't play by the rules, you lose. If you do you might win. Asking for the rules to be different, doesn't help you win the game .. so the mantra
Ruby is not xxxxx
where you can substitute for xxxxx the set of languages you are trying to force ruby to be.
Ron
···
2008/12/23 Just Another Victim of the Ambient Morality <ihatespam@hotmail.com>:
--
Ron Fox
NSCL
Michigan State University
East Lansing, MI 48824-1321