How do I do this type of for loop in Ruby?
for(int i=0; i<array.length; i++) {
}
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@johannes Reading a book is a good idea, but preferably not one about Ruby 1.6!Andrew Grimm– Andrew Grimm2012-04-10 01:12:46 +00:00Commented Apr 10, 2012 at 1:12
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Don't forget to take a look at some useful methods in ruby-doc: Enumerable module.Ivan Chau– Ivan Chau2015-03-23 07:20:52 +00:00Commented Mar 23, 2015 at 7:20
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10 Answers
array.each do |element|
element.do_stuff
end
or
for element in array do
element.do_stuff
end
If you need index, you can use this:
array.each_with_index do |element,index|
element.do_stuff(index)
end
7 Comments
jheriko
i was looking specifically for indexing in a loop, none of these solutions make it immediately obvious how to do that. the op betrayed his intentions with array.length in the code...
Eimantas
Read my answer carefully. There's a looping solution with indexing included.
Ruben Martinez Jr.
Often times,
each is great. But sometimes I just want a goddamn traditional for loop. Sometimes the "Ruby way" can be just plain annoying.
Muhammad Umer
how do i manually set index in ruby so i can write a sort myself
Muhammad Umer
what if i want to skip next two iterations
|
limit = array.length;
for counter in 0..limit
--- make some actions ---
end
the other way to do that is the following
3.times do |n|
puts n;
end
thats will print 0, 1, 2, so could be used like array iterator also
Think that variant better fit to the author's needs
Comments
I keep hitting this as a top link for google "ruby for loop", so I wanted to add a solution for loops where the step wasn't simply '1'. For these cases, you can use the 'step' method that exists on Numerics and Date objects. I think this is a close approximation for a 'for' loop.
start = Date.new(2013,06,30)
stop = Date.new(2011,06,30)
# step back in time over two years, one week at a time
start.step(stop, -7).each do |d|
puts d
end
Comments
The equivalence would be
for i in (0...array.size)
end
or
(0...array.size).each do |i|
end
or
i = 0
while i < array.size do
array[i]
i = i + 1 # where you may freely set i to any value
end
Comments
array.each_index do |i|
...
end
It's not very Rubyish, but it's the best way to do the for loop from question in Ruby
1 Comment
Dan Rosenstark
This is brilliant. It's true that the answer is not
each but rather each_index. +1To iterate a loop a fixed number of times, try:
n.times do
#Something to be done n times
end
Comments
If you don't need to access your array, (just a simple for loop) you can use upto or each :
Upto:
2.upto(4) {|i| puts i}
2
3
4
Each:
(2..4).each {|i| puts i}
2
3
4
answered Aug 16, 2013 at 13:31
Benjamin Crouzier
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Comments
What? From 2010 and nobody mentioned Ruby has a fine for /in loop (it's just nobody uses it):
ar = [1,2,3,4,5,6]
for item in ar
puts item
end
1 Comment
Wayne Conrad
One advantage of .each... do is that the block temporary falls out of scope at the end of the loop, whereas for...in leaves the temporary in scope.
['foo', 'bar', 'baz'].each_with_index {|j, i| puts "#{i} #{j}"}
Comments
Ruby's enumeration loop syntax is different:
collection.each do |item|
...
end
This reads as "a call to the 'each' method of the array object instance 'collection' that takes block with 'blockargument' as argument". The block syntax in Ruby is 'do ... end' or '{ ... }' for single line statements.
The block argument '|item|' is optional but if provided, the first argument automatically represents the looped enumerated item.