Flowdock
method

each_with_index

Importance_1
each_with_index() public

Iterates the given block for each element with an index, which start from 0. If no block is given, returns an enumerator.

Show source
Register or log in to add new notes.
February 3, 2013 - (v1_9_3_125)
0 thanks

How does enum#each_index differ from enum#with_each_index ?

Here is the working one each_with__index:

a=[11,22,31,224,44].each_with_index { |val,index| puts "index: #{index} for #{val}" if val < 30}
  index: 0 for 11
  index: 1 for 22
  => [11, 22, 31, 224, 44]

Below couldn’t produce the output, as with_index couldn’t work on the array.To make it workble, we need to first convert it to enumerator. And that can be done via the help of .to_enum, .each, or .map

a = [11,22,31,224,44].with_index { |val,index| puts "index: #{index} for #{val}" if val < 30}
=>NoMethodError: undefined method `with_index' for [11, 22, 31, 224, 44]:Array
       from (irb):2
       from C:/Ruby193/bin/irb:12:in `<main>'

Here is the working one with_index:

a = [11,22,31,224,44].each.with_index { |val,index| puts "index: #{index} for #{val}" if val < 30}
index: 0 for 11
index: 1 for 22
=> [11, 22, 31, 224, 44]