Loops in Ruby

Hi,

I have a very simple problem. I am a newbie to rails and for the life of me can't figure out why a simple incrementing loop is not printing to screen correctly. I know this has to be something simple but can't find anything specific to my problem.

<%= for i in 0..10 do puts "i is now #{i}" end %>

Prints to screen "0..10" as opposed to what I want:

0 1 2 3 4 5 6 7 8 9 10

Can someone help me with this very simple problem. I have tried until, .times, and while loops to no avail. So there must be some type of syntax magic I am missing.

Thanks in advance, Justin

Hi,

I have a very simple problem. I am a newbie to rails and for the life of me can't figure out why a simple incrementing loop is not printing to screen correctly. I know this has to be something simple but can't find anything specific to my problem.

<%= for i in 0..10 do puts "i is now #{i}" end %>

Because in a view you don't use puts (puts either goes nowhere or to a logfile somewhere). The <%= stuff the result of the chunk of code into the view, for a 'for' statement like you've got there then the result is the thing iterated over (ie 0..10).

you want something more like

<% looping construct of your choice do %>   i is now <%= i %> <% end %>

Fred

Hi,

I have a very simple problem. I am a newbie to rails and for the life of me can't figure out why a simple incrementing loop is not printing to screen correctly. I know this has to be something simple but can't find anything specific to my problem.

<%= for i in 0..10 do puts "i is now #{i}" end %>

Because in a view you don't use puts (puts either goes nowhere or to a logfile somewhere). The <%= stuff the result of the chunk of code into the view, for a 'for' statement like you've got there then the result is the thing iterated over (ie 0..10).

you want something more like

<% looping construct of your choice do %> i is now <%= i %> <% end %>

Fred

In addition to what Fred says, your other problem is that you have:    for i in <Range> do      #stuff    end and you want: (note there's no 'do' on a for loop)    for i in <Range>      #stuff    end so that would be:    for i in 0..10      #stuff    end

You're getting "0..10" because that's the value of the expression in the <%= %> Try this in irb and you'll see.

for i in 0..10   puts i   end

0 1 2 3 4 5 6 7 8 9 10 => 0..10

It's more likely, you want to have:

<% (0..10).each do |i| %>   i is now <%= i %> <% end %>

The difference being mainly that the local variable i will only exist inside the block and iterating over a collection using .each is much more common. See James Gray's article "Shades of Gray: The Evils of the For Loop" for a more thorough explanation.

-Rob

Prints to screen "0..10" as opposed to what I want:

0 1 2 3 4 5 6 7 8 9 10

Can someone help me with this very simple problem. I have tried until, .times, and while loops to no avail. So there must be some type of syntax magic I am missing.

Thanks in advance, Justin

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Rob Biedenharn http://agileconsultingllc.com Rob@AgileConsultingLLC.com

<% 0.upto(10) do |i| %> i is now <%= i %> <% end %>

Thank you! I figured it was just a simple thing I was doing wrong. Much appreciation!!

Justin

Hi,

I have a very simple problem. I am a newbie to rails and for the life

of me can’t figure out why a simple incrementing loop is not printing

to screen correctly. I know this has to be something simple but can’t

find anything specific to my problem.

<%=

for i in 0…10 do

puts “i is now #{i}”

end

%>

Because in a view you don’t use puts (puts either goes nowhere or to a

logfile somewhere).

The <%= stuff the result of the chunk of code into the view, for a

‘for’ statement like you’ve got there then the result is the thing

iterated over (ie 0…10).

you want something more like

<% looping construct of your choice do %>

i is now <%= i %>

<% end %>

Fred

In addition to what Fred says, your other problem is that you have:

for i in do

 #stuff

end

Actually, in the above, the ‘do’ is optional for both ‘while’, 'until, and ‘for’ loops

in both Ruby 1.8.x and 1.9.x. Thus, the above is legal Ruby. Furthermore,

one can write the above using a colon as follows in Ruby 1.8.x:

for i in :

#stuff

end

-Conrad