Introduction to the iterator IN Ruby

Each

The simplest iterator is to access all elements collected continuously.

 [1,3,5,7,9].each { |i| puts i }

 

Output result:

1

3

5

7

9

The unique function is to implement the for loop of the Ruby language. Because the built-in loop primitives in Ruby only include while and. For is just a syntax block. For example:

for song in songlist song.playend

 

Ruby will use the each iterator to convert:

songlist.each do |song| song.playend

Collect

It obtains each element from the collection and passes it to the block. The result returned by block is used to generate a new array, for example:

["H", "A", "L"].collect {|x| x.succ}

 

Output result:

["I", "B", "M"]

Inject

Although the name is not easy to understand, it is also a useful iterator that allows you to traverse all the members of a mobile phone to accumulate a value. For example:

[1,3,5,7].inject(0) {|sum,element| sum+element} --> 16[1,3,5,7].inject(1) {|product,element| product*element} –> 105