Welcome to OGeek Q&A Community for programmer and developer-Open, Learning and Share
Welcome To Ask or Share your Answers For Others

Categories

0 votes
702 views
in Technique[技术] by (71.8m points)

difference between each.with_index and each_with_index in Ruby?

I'm really confused about the difference between each.with_index and each_with_index. They have different types but seem to be identical in practice.

See Question&Answers more detail:os

与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
Welcome To Ask or Share your Answers For Others

1 Reply

0 votes
by (71.8m points)

The with_index method takes an optional parameter to offset the starting index. each_with_index does the same thing, but has no optional starting index.

For example:

[:foo, :bar, :baz].each.with_index(2) do |value, index|
    puts "#{index}: #{value}"
end

[:foo, :bar, :baz].each_with_index do |value, index|
    puts "#{index}: #{value}"
end

Outputs:

2: foo
3: bar
4: baz

0: foo
1: bar
2: baz

与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
OGeek|极客中国-欢迎来到极客的世界,一个免费开放的程序员编程交流平台!开放,进步,分享!让技术改变生活,让极客改变未来! Welcome to OGeek Q&A Community for programmer and developer-Open, Learning and Share
Click Here to Ask a Question

...