while is a keyword. It takes a condition argument and executes the code inside the delimiter while the condition is true.
while returns the last expression evaluated in its code. If
while is not executed (the condition is
false at the beginning), it evaluates to
i = 0 while i < 5 i += 1 p i end
until loop is the inverse of
while: it takes a condition argument and executes the code inside the delimiter while the condition is false (until the condition is true).
i = 10 until i < 5 i -= 1 p i end
One of the most used loop in programming, but in the Ruby world
for is generally considered less idiomatic than the
for num in [1, 2, 3, 4, 5] do puts num * 10 end