Addie's Calculator

calculator.rb

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+# gets and saves number from user
+def gets_valid_num
+  num = gets.chomp
+
+  # forces the user to input a number
+  while num.tr("0-9.-","") != "" || num == ""
+    print "Please give me a valid number: "
+    num = gets.chomp
+  end
+  return num.to_f
+end
+
+puts
+
+# gets math operation from user
+print "What type of math would you like to do? "
+operation = gets.chomp.downcase
+
+operations = ["add", "+", "subtract", "-", "multiply", "*", "divide", "/", "exponentiate", "^", "modulo", "%"]
+
+#forces user to enter an operator from 'operations'
+until operations.include?(operation)
+  print "Please give me a valid operation: "
+  operation = gets.chomp.downcase
+end
+
+puts
+print "Give me the first number: "
+num1 = gets_valid_num #get first number input
+
+puts
+print "Give me the second number: "
+num2 = gets_valid_num #get second number input
+
+# do math depending on the given operator
+case operation
+  when "add", "+"
+    answer = num1 + num2 #calculate the answer
+    operator = "+" #store a string version of the operator
+  when "subtract", "-"
+    answer = num1 - num2
+    operator = "-"
+  when "multiply", "*"
+    answer = num1 * num2
+    operator = "*"
+  when "divide", "/"
+    if num2 == 0 # if we try to divide by zero
+      answer = "undefined" # the answer will be undefined
+    else
+      answer = num1 / num2
+    end
+    operator = "/"
+  when "exponentiate", "^"
+    answer = num1 ** num2
+    operator = "^"
+  when "modulo", "%"
+    answer = num1 % num2
+    operator = "%"
+end
+
+# if a number's float equals its integer,
+# save the integer version for displaying purposes.
+if answer == answer.to_i
+  answer = answer.to_i
+end
+
+if num1 == num1.to_i
+  num1 = num1.to_i
+end
+
+if num2 == num2.to_i
+  num2 = num2.to_i
+end
+
+puts
+puts "MATH SAYS:"
+
+if operator == "^" # display exponentiation without spaces btwn nums
+  puts "#{num1}#{operator}#{num2} = #{answer}"
+else # display all other calculations
+  puts "#{num1} #{operator} #{num2} = #{answer}"
+end