CODEWITHSUNDEEP
ruby
Sonny Black
Sonny Black

Reputation: 1617

How to create a terminal calculator program in ruby?

So far I've got

puts "Enter a calculation: "

calc = gets.chomp

def add(a, b)
   puts a + b
end

puts add(calc)

And now I'm ashamed to admit but I'm stumped, I've tried writing add methods etc... but I just can't seem to wrap my head around getting this to calculate and output the correct results.

To simplify this, how can I get the ability to add working?

I.E user enters calculation (2 integers), program adds the calculation, program outputs results, program asks for another calculation.

Upvotes: 0

Views: 4422

Answers (5)

David Dreggors
David Dreggors

Reputation: 21

I know this is a bit older post, but people do still find this answer and I want to add to what jkrmr said above.

The code jkrmr posted is great but does not handle floating point calculations and that was an easy fix so I added that functinoality. :-)

#! /usr/bin/ruby

def calc
  puts "Calculator 1.1 \nEnter 'q' to quit."

  while true
    print ">> "
    str = gets.chomp.split(" ")  # splits into array, rejects blanks
    return if str[0] == 'q'      # quit if first element is 'q'
    if str[0].include? "."
      operand1 = str[0].to_f
    else
      operand1 = str[0].to_i
    end

    operator = str[1].to_sym

    if str[2].include? "."
      operand2 = str[2].to_f
    else
      operand2 = str[2].to_i
    end

    case operator
    when :+ then puts operand1 + operand2
    when :- then puts operand1 - operand2
    when :* then puts operand1 * operand2
    when :/ then puts operand1 / operand2
    when :% then puts operand1 % operand2
    else
      puts "invalid input"
    end
  end

end

if __FILE__ == $0     # if run as script, start calc: see http://j.mp/HOTGq8
  calc
end

Upvotes: 2

jmromer
jmromer

Reputation: 2236

I think this kind of script is perfect for a case statement. Here's a first pass that works with binary operators:

#! /usr/bin/ruby

def calc
  puts "Calculator 1.0 \nEnter 'q' to quit."

  while true
    print ">> "
    str = gets.chomp.split(" ")  # splits into array, rejects blanks
    return if str[0] == 'q'      # quit if first element is 'q'

    operand1 = str[0].to_i
    operand2 = str[2].to_i
    operator = str[1].to_sym

    case operator
    when :+ then puts operand1 + operand2
    when :- then puts operand1 - operand2
    when :* then puts operand1 * operand2
    when :/ then puts operand1 / operand2
    when :% then puts operand1 % operand2
    else
      puts "invalid input"
    end
  end

end

if __FILE__ == $0     # if run as script, start calc: see http://j.mp/HOTGq8
  calc
end

Then, at the command line:

$ ./calc.rb 
Calculator 1.0 
Enter 'q' to quit.
>> 55 / 5
11
>> 90 / 10
9
>> 5 * 3093
15465

Good luck!

These are great resources if you're just starting out: RubyMonk Codecademy

Upvotes: 3

Dan Baker
Dan Baker

Reputation: 1827

To build on that. If you want to continue to recieve calculation requests you can put the process in a loop(among many solutions).

while true
  puts 'Enter Val 1'
  v1 = gets.chomp.to_i
  puts 'Enter Val 2'
  v2 = gets.chomp.to_i
  puts "#{v1} + #{v2} = #{v1+v2} "
end

Upvotes: 1

CDub
CDub

Reputation: 13344

Here's a quick little calculator I whipped up to help you get started:

#! /usr/bin/ruby

def add(a, b)
  a + b
end

while(true) do
  puts "Enter a calculation: "

  # chomp off the \n at the end of the input
  calc = gets.chomp

  # quit if the user types exit
  exit if calc.include?("exit")

  # puts the result of the add function, taking input of calc "split" into two numbers
  puts add(calc.split("").first.to_i, calc.split("").last.to_i)
  # spacing
  puts
end

Upvotes: 1

Andrew Backes
Andrew Backes

Reputation: 1904

Just think of your problem one step at a time. You want the user to provide to integers. So start with a simple prompt, like you have already done:

puts "Enter your first value"

Now get the value from the user:

firstVal = gets.chomp

Now provide another prompt, and get a second value.

puts "Enter your second value"
secVal = gets.chomp

And output your results:

puts "#{firstVal} + #{secVal} = #{firstVal.to_i + secVal.to_i}"

Sometimes just writing it out plain and simple is the easiest first step. Now you can create an add function to do this more efficiently. Try it out, and see if you have any luck!

EDIT: Also, I noticed your add function takes two parameters, but you are only passing it one. In order to call a function with two parameters, you need two values to provide it with. For example:

x = 5
y = 2

def add(a, b)
    return a + b
end

puts add(x, y)

Upvotes: 2

Related Questions