Iterators in Ruby

1. It executes a block again and again.

2. In ruby array and hashes can be termed as collection.

3. Collection is basically a object that stores a group of data members.

4. Iterator return all the elements of collection.

5. Loops in ruby are used to execute the same block of code a specified number of times.

Ruby iterators.

1. Time : Will allow you to execute a loop

I = nil 3.times do |num|  i = num+1  puts i end

2. Each: returns the collection not the value

   Executes code for each element.

[1, 2, 3].each do |alpha|  puts “#{alpha}*2”end

result: 2,4.6

o. Each_Index:

[“a”, “b”, “c”].each do |alpha|  puts “#{alpha}” end

result: 0,1,2

o. Range

(0..5).each do |i|  # code end

3. Collect, Map:

  Collect returns all the elements of the collection.

   Collects what ever values are returned from each iteration of the block

a = [1,2,3] c = a.collect b= {“a” => 1, “b” => 2} d = b.collect

puts c.inspect puts d.inspect

results

[1,2,3] [["a",1],["b", 2]]

o Use Collect: to do something with Each of the value to get the new array

a = [1,2,3] b = a.collect{|x| 10*x} puts b.inspect

results [10, 20, 30]

4. loop iterators: for infinite loop

loop {puts "Hello"}

result

Hello, Hello, Hello etc

    so it needs control keywords and terminators like

i = 0

loop do  i += 1  print i  break if i==10 end

results: 1 2 3 4 5 6 7 8 9 10

5. Upto: We execute from number x to number y

1.upto(10) {|i| puts I}

similarly downto:

10.downto(1) {|i| puts I}

Results: 1 2 3 4 5 6 7 8 9 10

6. Step:

      Step to iterate While skipping over the range of number

1.step(10, 2){|i| puts i} results: 1 3 5 7 9

7. while

while condition do  code end

8. While modifier

begin    code end while condition

9. Until

until condition do    code end

10. for loop:

for i in 0..5    puts i end