Loops

Loops are used to repeat a task a number of times. A loop runs a set of instructions or functions a given amount of times as long as a condition is met. The most common loop in Ruby is the for loop. Other loops are while, until, and do...while.

For Loops

This loop is utilized when you know beforehand how many times you want to repeat the task.

for i in 1..5 do
  puts "Message number #{i}"
end

• The for keyword indicates the beginning of a loop.
• i is our variable.
• The in keyword indicates the range of numbers you want to loop over.
• The do keyword indicates the instructions you want to repeat.
• The end keyword indicates the end of the loop.

The output would be:

Message number 1
Message number 2
Message number 3
Message number 4
Message number 5

While Loops

The for loop is used when you know how many times you want to repeat the task, the while loop is used when you don’t know how many times you want to repeat the task.

i = 1

while i <= 5 do
  puts "Message number #{i}"
  i = i + 1
end

• The while keyword indicates the beginning of a loop.
• i <= 5 indicates that the loop will continue as long as i is less than or equal to 5.
• The do keyword indicates the instructions you want to repeat.
• The end keyword indicates the end of the loop.

The output would be:

Message number 1
Message number 2
Message number 3
Message number 4
Message number 5

Do…While Loops

The do...while loop is used when you don’t know how many times you want to repeat the task. The while loop is used when you want to check a condition before the first loop. do...while loops are used when you want to check a condition in the loop body after executing the statements. the do...while loop will run at least once.

i = 1

loop do
  puts "Message number #{i}"

  i = i + 1
  if i == 6
    break
  end
end

• The loop keyword indicates the beginning of a loop.
• if i == 6 is the condition that will break the loop.
• The do keyword indicates the instructions you want to repeat.
• The end keyword indicates the end of the loop.
• The break keyword indicates the end of the loop.

The output would be:

Message number 1
Message number 2
Message number 3
Message number 4
Message number 5

Until Loops

The for loops, while loops, and do...while loops run until a condition is no longer true. The until loops run until a condition is true.

i = 1

until i == 6 do
  puts "Message number #{i}"
  i = i + 1
end

• The until keyword indicates the beginning of a loop.
• i == 6 is the condition that will end the loop when true.
• The do keyword indicates the instructions you want to repeat.
• The end keyword indicates the end of the loop.

The output would be:

Message number 1
Message number 2
Message number 3
Message number 4
Message number 5