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There are a few different
variations of the loop in Ruby.

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One of those is the while loop.

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The while loop is similar
to the loop statement and

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it uses a conditional
to perform the logic.

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However, the big difference is that
the while loop continues to run

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as long as the conditional that is
set up top continues to return true.

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The condition is also specified as
part of the argument, the while loop.

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Let's see how that works now,
using work spaces.

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Using a Ruby work space,
let's go ahead and

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create another file called while _loop.rb.

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And let’s go ahead and
write a very simple while loop.

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We’re going to say the answer
is an empty string and

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while the answer does
not equal the letter n,

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we’ll print out do you want me to
repeat this pointless loop again?

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And then we'll get the answer
from standard input,

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remove trailing spaces,
and make it lowercase.

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We write a while loop similar to the way
we write a regular loop except we

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use the while keyword, and then we set the
condition at the top of the while loop.

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As soon as that condition is met
it will exit the while loop.

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Let’s run this and see how it goes.

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Do I want to repeat
the pointless loop again?

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Yes.

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Do I want to repeat
the pointless loop again?

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No.

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And we can see that will
exit the while loop.

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When we use a while_loop, there's no
need to manually use the break key word.

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Now let's create another
file called while_number.rb.

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And clear my screen there.

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And we're going to create a very
simple method that prints hello,

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and takes one argument which is
the number_of_times, to print hello.

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And what we're gonna do is create
a simple variable here called i.

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When you're writing loops,
it's conventional to use the letter i,

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j, and k to iterate over the loop.

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The reason that we use a lower-case i

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is because that's going to
means it's an iterator.

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So now we'll say, while i is less than
the number_of_times, which is the argument

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to the function, will print hello,
and then this is really important,

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we increment i or
else we'll cause an infinite loop.

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So, now that we've got this method,
let's go ahead and call it.

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We'll create an empty answer string

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And we'll say while
the answer is less than 5,

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because we don't want to be
printing this out too much.

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We'll print,
how many times do you want to print hello?

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And add a little message,
enter number greater than five to exit.

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Then we'll get the answer and

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convert it to an integer and
then we can call that method.

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With the answer.

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Now let's go ahead and run this.

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Oh, comparison of string with five
failed and that's on line 10.

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Let's go ahead and change the answer
to zero instead of a string.

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Run that again.

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How many times do I want to print hello?

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How about 3.

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Okay, it printed three times.

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It printed two times.

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And now let me type the number 6.

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And then it prints six times and exits.

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The reason that prints hello six times and
then exits,

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is because print_hello is
still part of the loop.

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This block of code will not be
run again until after It exits.

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The while loop will then
evaluate the condition

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in the context of the end
of the block of code.

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Try practicing writing while loops
on your own now using WorkSpaces.