# while, until and for Loop

## while Loop

In Ruby, while is a keyword. It takes a condition argument and executes the code inside the delimiter while the condition is true.

Like method, while returns the last expression evaluated in its code. If while is not executed (the condition is false at the beginning), it evaluates to nil.

i = 0

while i < 5
i += 1
p i
end

## until Loop

The 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

## for Loop

One of the most used loop in programming, but in the Ruby world for is generally considered less idiomatic than the each method.

for num in [1, 2, 3, 4, 5] do
puts num * 10
end