Experimental Calculator

Ruby
1

Hey, I’m new to the forum and I’ve just learned Ruby. I’ve been trying
to make a calculator and its giving me an argumenterror (def add) and
querying my ‘if’ statements. Here is my code:

puts “Input first number.”
y = gets.chomp

puts “Input second number.”
x = gets.chomp

puts “What is your function? (add,subtract,multiply,divide)”
z = gets.chomp.downcase

def add(y, x)
y + x+
end
def subtract(y, x)
y - x
end
def divide(y, x)
y / x
end
def muliply(y, x)
y * x
end

if z == add
puts add

elsif z == subtract
puts subtract

elsif z == multiply
puts multiply

elsif z == divide
puts divide

else puts “Function not valid.”

end

Can anyone tell me what could be wrong?

2

There’s a bunch of things wrong, and you might be able to figure them
out, using the error messages that Ruby will give you.

You have a “+” too many in you “add” method, and you aren’t calling your
methods with parameters in you if-else. You are trying to call e.g.
“add” instead of comparing with the string “add”. You are also not doing
operations on numbers, but rather on string. This can be mended by
calling “to_f” on the number from input.

Here’s a working version:

puts “Input first number.”
y = gets.chomp.to_f

puts “Input second number.”
x = gets.chomp.to_f

puts “What is your function? (add,subtract,multiply,divide)”
z = gets.chomp.downcase

def add(y, x)
y + x
end

def subtract(y, x)
y - x
end

def divide(y, x)
y / x
end

def muliply(y, x)
y * x
end

puts case z
when “add”
add(y, x)
when “subtract”
subtract(y, x)
when “multiply”
multiply(y, x)
when “divide”
divide(y, x)
else
“Function not valid.”
end

3

Nice, Thanks for the help. is there a way it could have been done with
the usual if and else statements?

4

Taj Blah wrote in post #1167184:

Nice, Thanks for the help. is there a way it could have been done with
the usual if and else statements?

Of course. The “case” is just a fancy way of writing if-else-statements:

if z == “add”
puts add(y, x)
elsif z == “subtract”
puts subtract(y,x)
elsif …

5

Nice. Okay, so let’s say I was satisfied with the code and I wanted to
turn it into an exe. file. What would be my next step?

6

Taj Blah wrote in post #1167223:

Nice. Okay, so let’s say I was satisfied with the code and I wanted to
turn it into an exe. file. What would be my next step?

Then I suggest you find another programming language.

Ruby is an interpreted language. This means that you have an
interpreter, ruby, which reads the source-file line by line and executes
it. It doesn’t get compiled into a binary first, like you’d see with a
compiled language, like C, Java or Haskell.

This of course means that the receiving end has to have the interpreter,
and more so, the same version of the interpreter (most are backwards
compatible, but we did introduce a new hash syntax back in 1.9)

7

If you really want to compile the Ruby code into an EXE-file, you can
use a tool like OCRA: GitHub - larsch/ocra: One-Click Ruby Application Builder

This will package your Ruby code together with the Ruby interpreter and
merge it into an EXE-file to be run on Windows.

8

Wow, I guess it’s back to Java for now. Thanks for the help. Much
appreciated.