Question

I’m getting the following error:

/calcTax.rb:9: syntax error, unexpected $undefined
  grandtotal = $#{subtotal - tax}

From this code:

print('What amount would you like to calculate tax for?  $')
subtotal = gets.to_i
taxrate = 0.078
tax = subtotal * taxrate
if (tax > 0.0)
  grandtotal = $#{subtotal + tax}
else if (tax < 0.0)
  grandtotal = $#{subtotal - tax}
puts "Tax on $#{subtotal} is $#{tax}, so the grandtotal is $#{grandtotal}."

I’m wondering if I need to set subtotal to a value in a different way, or what I can do to repair my program?

I’m also getting an unexpected $end error on line 10.

Answer 1

There’s a couple of things wrong with your syntax here.

First of all, the $#{blah} syntax is only needed (and only valid!) when inserting variables into a quoted string. When you’re just performing calculations, you can simply say something like:

grandtotal = subtotal + tax

You’ll also need to add a then at the end of both if lines, change else if to elsif, and add an end after the second grandtotal line. With this work all done, you should have:

print('What amount would you like to calculate tax for?  $')
subtotal = gets.to_i
taxrate = 0.078
tax = subtotal * taxrate
if tax > 0.0 then
  grandtotal = subtotal + tax
elsif tax < 0.0 then
  grandtotal = subtotal - tax
end
puts "Tax on $#{subtotal} is $#{tax}, so the grandtotal is $#{grandtotal}."

Which seems to work.