Ruby: How to iterate over a range, but in set incr

问题:

So I'm iterating over a range like so:

(1..100).each do |n|
    # n = 1
    # n = 2
    # n = 3
    # n = 4
    # n = 5
end

But what I'd like to do is iterate by 10's.

So in stead of increasing n by 1, the next n would actually be 10, then 20, 30, etc etc.

回答1:

See http://ruby-doc.org/core/classes/Range.html#M000695 for the full API.

Basically you use the step() method. For example:

(10..100).step(10) do |n|
    # n = 10
    # n = 20
    # n = 30
    # ...
end

回答2:

You can use Numeric#step.

0.step(30,5) do |num|
  puts "number is #{num}"
end
# >> number is 0
# >> number is 5
# >> number is 10
# >> number is 15
# >> number is 20
# >> number is 25
# >> number is 30

回答3:

rng.step(n=1) {| obj | block } => rng

Iterates over rng, passing each nth element to the block. If the range contains numbers or strings, natural ordering is used. Otherwise step invokes succ to iterate through range elements. The following code uses class Xs, which is defined in the class-level documentation.

range = Xs.new(1)..Xs.new(10)
range.step(2) {|x| puts x}
range.step(3) {|x| puts x}

produces:

1 x
3 xxx
5 xxxxx
7 xxxxxxx
9 xxxxxxxxx
1 x
4 xxxx
7 xxxxxxx
10 xxxxxxxxxx

Reference: http://ruby-doc.org/core/classes/Range.html

......

回答4:

Here's another, perhaps more familiar-looking way to do it:

for i in (0..10).step(2) do
    puts i
end