Forum: Ruby Code wont run due to errors

I am attempting to make a Vector Calculator, that will take either
coordinates, or an already given vector. The if and elsif blocks work
fine, it is the else block that I am in need of help in. I want the code
to re-run from the "answer = gets.chomp.to_i" line if the answer does
not equate to "given" or "coordinates", but when i run the code I am
given the following errors:

vector_calc.rb:48: warning: string literal in condition
vector_calc.rb:51: warning: string literal in condition
vector_calc.rb:50: Invalid retry
vector_calc.rb: compile error (SyntaxError)

The code is below.

puts "Are the vectors given, or do you only know coordinates?"
puts "Please answer either 'given' or 'coordinates'."

begin
answer = gets.chomp.downcase

  if answer == "coordinates"
    puts "What is the x-value of your first coordinate?"
    x1 = gets.chomp.to_i

    puts "What is the y-value of your first coordinate?"
    y1 = gets.chomp.to_i

    puts "What is the x-value of your second coordinate?"
    x2 = gets.chomp.to_i

    puts "What is the y-value of your second coordinate?"
    y2 = gets.chomp.to_i

    coord_1 = [x1, y1]
    coord_2 = [x2, y2]

    puts "Point A = (#{x1}, #{y1})"
    puts "Point B = (#{x2}, #{y2})"

  elsif answer == "given"
    puts "What is vector A's x-value?"
    vect_Ax = gets.chomp.to_i

    puts "what is vector A's y-value?"
    vect_Ay = gets.chomp.to_i

    vect_A = [vect_Ax, vect_Ay]

    puts "What is vector B's x-value?"
    vect_Bx = gets.chomp.to_i

    puts "what is vector B's y-value?"
    vect_By = gets.chomp.to_i

    vect_B = [vect_Bx, vect_By]

    puts "Vector A = [#{vect_Ax}, #{vect_Ay}]"
    puts "Vector B = [#{vect_Bx}, #{vect_By}]"
  else
      if answer != "given" || "coordinates"
        then puts "Please answer either 'given' or 'coordinates'."
      end
    until answer == "coordinates" || "given"
      retry
    end
  end
end


P.S I am creating this code as part of an outcome to a research project,
and am asking your permission to use your answer to this question as
evidence to my folio.

On Wed, Dec 5, 2012 at 7:27 AM, Nuggety Nanna <lists@ruby-forum.com> 
wrote:
> vector_calc.rb: compile error (SyntaxError)
>     puts "What is the x-value of your first coordinate?"
>
>     puts "what is vector A's y-value?"
>     vect_B = [vect_Bx, vect_By]
>   end
> end

The conditions are wrong:

1.9.2p290 :001 > answer = "x"
 => "x"
1.9.2p290 :002 > if answer != "coordinates" || "given"
1.9.2p290 :003?>   puts "a"
1.9.2p290 :004?>   end
(irb):4: warning: string literal in condition
a

A string literal will always evaluate to true in a boolean comparison:

if answer != "coordinates" || answer != "given"

Now, the || (or) is wrong, because any word is either != "coordinates"
or != "give". You want && (and):

if answer != "coordinates" && answer != "given"

But, as you have this comparison in an else of an if that is comparing
answer to coordinates and given, it's not even needed.

Anyway, I think it would be simpler if you moved this logic to the
beggining of your code:

begin
 puts "Please enter coordinates or given"
  answer = gets.chomp.downcase
end until answer == "coordinates" || answer == "given"
# at this point you know that answer is either coordinates or given
if answer == "coordinates"
[...]

> P.S I am creating this code as part of an outcome to a research project,
> and am asking your permission to use your answer to this question as
> evidence to my folio.

NP.

Jesus.

answer = 'hello'

if answer != "given" || "coordinates"
  puts "Please answer either 'given' or 'coordinates'."
end

--output:--
1.rb:5: warning: string literal in condition


1)
answer = 'hello'

if answer != "given" and answer != "coordinates"
  puts "Please answer either 'given' or 'coordinates'."
end

2)
answer = 'hello'

if not ["given","coordinates"].include?(answer)
  puts "Please answer either 'given' or 'coordinates'."
end


============

begin
  answer = gets.chomp.downcase

  until answer == "coordinates"
    retry
  end

end

--output:--
1.rb:5: Invalid retry
1.rb: compile error (SyntaxError)


You are trying to learn ruby by skipping the basics--that can't be done.

Thanks for that. I'll give it a try and let you know how it goes.

Shouldn't this:

if answer != "given" || "coordinates"

until answer == "coordinates" || "given"

Be this?

if answer != "given" && answer != "coordinates"

until answer == "coordinates" || answer == "given"


And your "retry" must be in the wrong place or context, doesn't it have 
to be inside a "rescue"?