DEV Community

Cover image for Sharpen your Ruby: Part 5
Eric The Coder
Eric The Coder

Posted on • Updated on • Originally published at eric-the-coder.com

Sharpen your Ruby: Part 5

I develop in Javascript, Python, PHP, and Ruby. By far Ruby is my favorite programming language.

Together let start a journey and revisit our Ruby foundations.

Follow me on Twitter: EricTheCoder_

Classic Loop

In Ruby like any other programming language we can iterate a number of fix or variable times. Here are a classic infinite loop that will execute until the program crash.

loop do
  put 'Hello World'
end
Enter fullscreen mode Exit fullscreen mode

While loop

It is possible loop while a condition is meet.

number = 0
while number < 100
  puts number
  number += 1
end
# Will print numbers from 0 to 99
Enter fullscreen mode Exit fullscreen mode

Loop until

It is possible loop until a condition is meet.

number = 0
until number == 10
  puts number
  number += 1
end
# Will print numbers from 0 to 9
Enter fullscreen mode Exit fullscreen mode

Loop x number of times

(1..10).each do |i|
  puts i
end
# print numbers from 1 to 19
Enter fullscreen mode Exit fullscreen mode

or also

10.times { puts "Hello World" }
Enter fullscreen mode Exit fullscreen mode

Loop through each element

By far, the most use loop is the 'each' iteration

# Array of names
names = ['Peter', 'Mike', 'John']

# Iterate the names list
names.each do |name|  
   puts name
end

# or shorthand version
names.each { |name| puts name }
Enter fullscreen mode Exit fullscreen mode

Break and Continue

It is possible to stop the loop before the end. It is also possible to skip one iteration and go to the next one.

names.each do |name|  
  next if name === 'Mike' 
  puts name
end
# Peter 
# John
Enter fullscreen mode Exit fullscreen mode

The iteration will skip the puts statement if the name is equal to Mike

names.each do |name|  
  break if name === 'Mike' 
  puts name
end
# Peter
Enter fullscreen mode Exit fullscreen mode

The iteration will stop if the name is equal to Mike.

Exercise

Create a little program that:

  • Create a loop with 10 iterations (from number 1 to 10)
  • Each iteration will print only if the iteration number is even. Odd number will be skip.

Solution

10.times do |num|
  next if num.odd?
  puts "Number #{num}"
end
Enter fullscreen mode Exit fullscreen mode

Conclusion

That's it for today. The journey just started, stay tune for the next post very soon. (later today or tomorrow)

If you have any comments or questions please do so here or send me a message on twitter.

Follow me on Twitter: EricTheCoder_

Discussion (1)

Collapse
dhavalsingh profile image
Dhaval Singh

in the -> Loop x number of times part it should be
# print numbers from 1 to 10.
Good article for new learners btw!