Queues - Erica Case - Calculator.rb

Calculator.rb

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+# user inputs the type of operation
+def get_op
+  puts "\nWhat operation would you like to perform? "
+  print "You may + (add), - (subtract), * (multiply), or /  (divide): "
+  user_op = gets.chomp
+
+  # downcase words (downcasing symbols produces error)
+  if user_op.scan(/\w/).length == user_op.length
+    user_op.downcase!
+  end
+
+  # validate user input
+  until ["add", "subtract","multiply", "divide", "+","-", "/", "*"].include? (user_op)
+    print "Invalid input: Please enter a valid operation (+, -, /, *): "
+    user_op = gets.chomp
+  end
+
+  return user_op
+end
+
+# check whether only numbers are entered
+def check_number(num)
+  until num.to_i.to_s == num || num.to_f.to_s ==  num
+    puts "That is not a number.  Please try again!"
+    print "Please enter a number: "
+    num = gets.chomp
+  end
+  return num.to_f
+end
+
+
+# input two numbers into an array
+def get_numbers
+  num = Array.new(2)
+  2.times do |iter|
+    print "Enter ##{iter + 1}: "
+    num[iter] = check_number(gets.chomp)
+  end
+  return num
+end
+
+
+# calculate the specified operation on the two numbers and return output
+def do_calc(op, numbers)
+  case op
+  when "+", "add"
+    puts "#{numbers[0]} + #{numbers[1]} = #{numbers.inject(:+)}"
+  when "-", "subtract"
+    puts "#{numbers[0]} - #{numbers[1]} = #{numbers.inject(:-)}"
+  when "*","multiply"
+    puts "#{numbers[0]} * #{numbers[1]} = #{numbers.inject(:*)}"
+  when "/", "divide"
+    print "#{numbers[0]} / #{numbers[1]} = "
+    if numbers[1] != 0
+      puts "#{numbers.inject(:/)}"
+    elsif numbers[0] < 0
+      puts "NEGATIVE INFINITY"
+    elsif numbers[0] > 0
+      puts "INFINITY"
+    else
+      puts "UNDEFINED"
+    end
+  end
+end
+# I let the user do multiple calculations because otherwise using methods is silly
+print "Would you like to use the calculator (y/n)? "
+use_calc = gets.chomp
+#gets.chomp.downcase
+
+while use_calc == "y"
+  operation = get_op
+
+  puts "Enter two numbers that you would like to #{operation}? "
+  user_num = get_numbers
+
+  do_calc(operation, user_num)
+  print "Would you like to do another calculation? "
+  use_calc = gets.chomp
+end