Ruby while loop with math

Question

I am working on a lab for class about 'while' loops. This is the goal:

Create a variable and set it equal to true

While the variable you just created is true

Prompt user for number

Read in number

Compute double that number

Display double that number

Prompt the user if they want to go again

Read in that text

If that text input is “n” then set the true variable to false

This is the code I have:

puts "Enter a number"
x = Float(gets.chomp())

product = x * 2
puts "Double your number is"
puts product

while
  puts "Go again   y/n?"
  answer = gets.chomp
  if answer != 'y'
  end
end

The directions seem clear, but I don't understand how to turn it into code.

Any modifications will help.

Hint #2: "While the variable is true". See this on how to properly write a while loop. — jvillian
– jvillian, Commented Oct 18, 2017 at 19:47
Hint #3: Everything that is supposed to happen "while the variable is true" needs to go inside the while loop. — jvillian
– jvillian, Commented Oct 18, 2017 at 19:50
Note that in Ruby the style is generally x = gets.chomp.to_f where empty argument lists are omitted and force-casting with things like Float() is strongly discouraged. — tadman
– tadman, Commented Oct 18, 2017 at 20:10
@Stefan In C++, PHP and others you'd write (float) x where that converts x to a float. Naturally some people think that the equivalent in Ruby would be Float(x), since as far as syntax goes thats' the closest, but it's actually x.to_f due to the principle of Duck Typing. In other words, any object that can handle a .to_f call is an acceptable value, not necessarily one that plays nice with Float. — tadman
– tadman, Commented Oct 19, 2017 at 16:18

Robert · Accepted Answer · 2017-10-19 19:18:29Z

1

You need to have a boolean flag to check at while level each loop:

again = true

while again
  puts "Enter a number "
  x = Float(gets.chomp())

  product = x * 2
  puts "Double your number is"
  puts product 

  puts "Go again y/n? "

  again = gets.chomp != 'n'
end

edited Oct 19, 2017 at 19:18

answered Oct 18, 2017 at 20:23

Robert

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7 Comments

tadman Over a year ago

Could always loop do ... end and then break if answer.downcase == 'y'

Robert Over a year ago

True. But the requirement asks for a Boolean var.

Stefan Over a year ago

if answer == 'n' would match the requirements more closely.

tadman Over a year ago

Could do again = answer == 'n' if that's the case, no need for the if in that case. This is an XY problem, so don't be afraid to get to the root of the issue.

Robert Over a year ago

@tadman, nice tip! Updated. PS: it should check for != 'n' to loop again.

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