Crystal Notes: Loops

published: 29th of July 2021

Intro

Crystal has a set of looping structures similar to what can be found in other languages.

Each

An each loop is similar to a for loop in other languages.

crystal 
# Example each loop.
stuff_and_things = ["stuff", "things"]
stuff_and_things.each do |item|
  puts item
end

# Example each loop with an index.
stuff_and_things = ["stuff", "things"]
stuff_and_things.each_with_index do |item, idx|
  puts "#{idx} - #{item}"
end

Times

times allows you to iterate for N number of iterations.

crystal 
# Exampe times block.
10.times do 
  puts "Show me your stuff"
end

While/Loop

while and loop have similar behaviour and start an infinite loop. It is up to the user to program the exit condition.

crystal 
# Example of while loop.
is_true = true
while is_true
  puts "blah"
  is_true = false
end

# Example of a loop...er loop. 
# Usefull if you want a single iteration.
is_true = true
loop do
  puts "blah"
  break if is_true
end

https://pragprog.com/titles/crystal/programming-crystal/

https://crystal-lang.org/reference/syntax_and_semantics/while.html